Don’t even talk yourself down about how this is boring....I came here because I needed some help and you did a better job than any other video I’ve watched and I appreciate your time for that, this video is older but I never needed anything like this until now, but this was easily one of the best transistor-fix videos out there, very, very clear and I learned quite a bit from your video. Thank you
Funny thats basicly what i just told him to right now i didnt see your re$ponse till after but i clicked the like button on your reply as well as the main video
Just watched one video on fixing broken amps which was useless and longer, then I came here and found what I needed to understand. Thanks a lot. I've been quoted $500 to fix my amp. I could buy a new car for that.
Hi, I am very grateful for your video. You may not realise, but you have given some very important information about how things work which are missing in other electronic repair videos. As a hobbyist, I have learnt a lot from you. Thank you.
DUDE!!! Thank you!! I sincerely appreciate your time. I've been trying an hour per day for FIVE months now to figure out how to fix my Pops amp. He passed a couple years back and this thing is pretty much all I have that lets me feel like we're still hangin' together and jammin' ... then it croaked about 6 months ago ... well at least one channel did. I knew it was one of the damned little transistor thingys after watching so many vid's and reading so much, but this was the FIRST one that I actually understood what those 3 stupid leg thingys do and why and how to work forward or back to find the other crap they screwed up along the way, so I can FINALLY rock out with Pops again ... well in spirit anyways ... and ashes too, a bit of em anyways I put in a glass thingy I glued to the top of the sub so he can still dance to the "tight bass response" of his Onkyo he always talked about, whatever the hell that means. I just know it sounds killer when it's working right, and I think I can finally feel comfortable about digging into this little F***er that's been my nemesis for months now. So dear Sir, again, please know that my gratitude is limitless at the moment for you and your valuable time that you've freely shared here .. I truly and deeply appreciate you and your efforts along with your ability to explain it so even an idiot artist completely ignorant of any technical knowledge and skills like myself could understand. It clicked ... and I bet dimes to donuts I kick this things arse now, I just know it!! Thank you SIr!!! ✌️
I am very impressed with your skill at teaching something that you yourself had only just learned. We the audience were clueless that you were new at this until you admitted it. Thank you for taking the time to make such a great and helpful video covering a subject that you have obviously discovered that is rarely broached yet needed to be covered.
Definitely, the explanation here on the issue of replacing power transistors will be the best I have ever seen, including some aspects that may be less clear to most people not trained in this activity.
This is one of the best video to simplify a audio amp out transistor thanks a lot u couldn't have made it any easier thanks again all thumbs up love the video
Absolutely great video.. you are a natural teacher and excellent at explaining stuff. Thankyou so much .. please make more.. ill bet you’d be really popular if you had a repair channel on here..excellent stuff! Not long not boring always moving forward in a way that makes sense. The transistor explanation was excellent and building from there was very informative .. thx again
That was the best explanation of a transistor I've ever heard! I've been learning about this stuff for several years and never felt I understood transistors as well as I do now. You've earned a sub for that alone
Where you think you talking alot, and making no sense, you've just helped someone who listen alot to music but couldn't tell you why something has blown, and now I'm using TOUR knowledge you've shared to go and tackle a crown xti amp, that starts up then shuts down!!! So THANK YOU
Thanks for posting this! Before I watched this, I’d never considered pulling a bad transistor and the amp will still work, albeit with less power output than before, but the point is, it’ll still work! I tried it on a vintage BGW amp I have with a blown channel, and transistors made of unobtainium, and it worked! I removed the same transistor from the opposite side, even though it was good, so both channels would have equal output, and Shazam! An amp that hadn’t worked in 20 years was back in service! THANKS again!😉😎👍🏻
christopher fogarty lols if you’re just pulling out transistor that is fine but if you have a bad one it will not work basically if you pull the bad transistor it may work just like what you did
I think the first thing I would do before any thing else is to blow out all the dust and dirt. Quite often overheating is the issue leading to blown transistors. Air flow is very important if the amplifier is driven hard. Once fixed any air filters should be well cleaned, check the fan, apply a little oil if needed. If you don't do this, it will probably blow up again.
You're absolutely right. I wound up going back in and blowing it out after I replaced the transistor. This one blew after it melted a 1/4" instrument cable which was connected instead of a proper speaker cable, but I doubt the excessive dust helped things.
Dude. You definitely did not make a fool out of yourself. Your explanation put me on the right path for me trying to fix my reciever. It is not the same but it works the same. Thank you very much. You rock!
Brother, you brought back memories of my High School Electronics classes, and you're probably better at electronics than I am. Ill tell you one thing tho. You refreshed my memory on the transistor and resistor topics. So thank you for taking the time to make this.
Dude, I am extremely thankful that you put this video together!! I have a similar issue but I have just started down this long and dark path that lead me down to a rabbit hole I couldn't help but dive into! I have a board that keeps blowing a fuse on a bass amp that I don't have any of those round guys that you were showing I have these square ones that are on an aluminum plate and I want to say that they're bridge transistors, but I am not sure but there is solder missing on a couple of the points and I wanna say that is the problem. But I'm just not sure.
I loved this video!!! I watched it right to the end and I learned a lot. I am a newbie at this field but dabbled with it a long time ago. I have the same amp, it's great a real work horse. You are a really good teacher and I hope to see more of your videos. You have a knack of explaining things that keep me and hopefully others focused to the job. Thanks again and take care.
When I brought my amp in for service I mentioned that it was blowing fuses. The tech just said "Probably a transistor". He was right and it cost me $85. Your video explains perfectly how he would've known what was wrong and now I have a bit more knowledge. Thanks!
Just FYI, that’s not a “1” on the multi-meter. It’s an “L”. Some meters will say “OL” which stands for “out of limits”. Means the resistance is outside the limits you’ve chosen to test because the two probes aren’t actually being connected through anything - cuz the fuse is blown. If a connection is made between the two probes THROUGH the fuse it will show the value of resistance in the object that’s being used to bridge them together. Good video.
it's a 1 on his meter. his meter doesn't display letters.. only numbers. But 1 on his meter means the same as 'OL' on your meter. not all meters are made the same.. different displays..some are alphanumeric, but the he's using is numeric. it displays and communicates the same information though, so he was reading it correct. 1 shows there is resistance. good fuses will show continuity..just like he said. sometimes I don't understand why people feel the need to "correct" things that are not wrong..
Excellent Video ! Like you I have searched hours to try and find enough info to try and track down faulty components in an Amp. Most of the ones I have found assume that you are already something of an electronics expert, so don't give such a good and detailed explaination as you have here. Can't praise you enough, but my thanks.
Hey thanks! This video was actually super helpful. I've been wanting to get into fixing electronics for a while so I went and got myself a gig fixing amplifiers and speakers for a local pawn shop today. I have no clue what I am doing and I like the way you explain things and it wasn't boring at all!
I watched several videos on fixing electronics and this is hands down the best one yet. So much valuable information. Spoke in plain english, not some text book confusion. Thank you!
I can't imagine this has not been pointed out yet but the solder pads on the board connect to the Base and Emitter. The Collector is the big metal case on the other side. On this model QSC amp the collectors are grounded directly to the aluminum heatsink. Most amps isolate the collector with an insulator, some of which require thermal transfer compound, others do not. It is also quite common for other components to short (or open) along with the power transistors. While I understand that you are trying to help people out and save them money, you are in effect giving them just enough information to possibly do serious damage to their amp or to themselves in the process. It isn't always as easy as it looks folks.
Seriously thank you thank you thank you more times than I can say. I’ve had my kenwood stereo system for so long and the power amp recently ‘shut off’ ( no signal lights or sound going to speakers) and if not for the video I would’ve have had to spend 100+ on a new one or having someone else repair it so again thank you so much dude. 5 years later and literally your still the only video online I can find that explains this in a way someone who grew up just doin it myself and not knowing professional terminology can understand 😂😂
Driving a speaker load with a guitar cable is always s bad idea. Good clarity on your explanation of tracing out the faulty output transistor. Did you know that dust becomes conductive after heat and current flow hit a trigger point? That sends the DC rail voltage where it should never go...avalanche voltage breakdown followed by shorted output devices. Clean away the dust and check the mica wafer for cracks. Replace the wafer if it looks compromised.
Very good presentation and explanation of the circuitry. I've dabbled with electronics about 40 years ago and you brought back memories of those days. Thanks
Awesome vid .. I have a QSC PL9 and one of the channels stop working. I was about to bring it for service and like you already know, it is an outdated AMP which would cost me $$$$$ then who to tell, similar issues can resurface again ... knowledge is POWER. Thank you for such detailed vid for DIY like myself ... you just saved me $$$$$$$ for now :)
Buying a new stereo amp is difficult today, all you find are 5.1 and up surround amps with more than two speakers, so repairing my Sherwood receiver was my best option, I found thst it uses a combo of B1560/D2390 transistors, I found a set of 5 pairs on e-bay for less than $15.00, this vdeo was very helpful in finding the fault quickly, thank you.
I'm far less knowledgeable than you are, but wasn't totally lost. Thanks for the help. I'm here because I have several 70s receivers that have problems. Most all don't put out sound from the right speaker, across all channels. So, no stereo but I can play both speakers if I use 2 channels. Your video was the first to explain what was wrong(I guessed correctly, but didn't know the terms), why and how, and also explained how to fix it as well. Thanks a million!!! If you have time, I have more questions so I don't ruin a couple really nice amps, or rather "stereo receivers"... I have a 1970 Kenwood kr-6160, and my favorite and cult following unit, the 1976-1979 Sansui 9090db. A few others of the Era, but these are my favorites.
I like that you literally explain what the difference is of each channel was and where that that break comes into I didn't really fully understand the admit her the bass and The Collector and what the percentage of them actually working is until you fed me this information I think you would be an excellent teacher for anyone
while i was listening to your video i was fixing a jb systems vx400. or trying to fix it. i'm no electronics guy. it is because of guy's like you that i can learn how to fix things !!! thank you very much !
Man this is the way I wanna be taught!! By a guy who learned it himself and can explain it in simple language. This was great. Pretty sure thats what I got going on here. Not sure Im gonna do it myself yet. Not the best with a solder gun But I really wanna learn this stuff and your explanation was great. Just like everybody else said great job.
Excellent video ! Like you i've done a lot of searching to get enough info to track down faulty component(s)i in an Amp. Most of the ones I have found assume that you are already something of an electronics expert, so don't give as good an explaination as you have here. Can't praise you enough.
Will give this a try. Whether or not it works to diagnose if one or more output transistors is blown on my amp, I learned useful info. Thanks much. Great video.
Awesome! Thanks for the video. I've always been interested in electronics, and unfortunately did exactly what you said not to do. I replaced a fuse and turned my amplifier back on. I have a Mackie M2600. When I went to turn it off, I didn't hit the switch all the way. It shut off for a split second, and came back on. It tripped the breaker in the basement. When I turned it back on, it powered up for about 6 seconds, and then the fuse blew. I never had any problems before, and knowing it was a slow blow fuse, I ASSumed that was the only problem. After replacing the fuse, it powered back up and stayed on, but when I went to put power to it, the "protect" and "short" lights lit on channel 1. It was fine at low volume, but given some power, both lights lit up. From what you explained in the video, and what I've experienced, I'm guessing a short between collector and base - and who knows what other damage it may have caused! Looks like I'll be taking this one to the shop, but the video was still very informative, and I now I know what a transistor does!
Bro! Best germanium amp fixing video on TH-cam, not long nor boring, exactly what one is looking when trying to troubleshoot and fix one of these things. Thank you very much for taking the time and effort of doing this for all of us! Cheers!
That was an excellent video and a fantastic explanation. I have instrumentation background and an electronics degree. I also own a DJ company and have always sent the amps back to manufacturer to be repaired due to time constraints. i have so many amplifiers that need replaced that i am going to fix them myself. This was a great quick troubleshooting video. Well Done!!!!
I agree w/ @stevie-joe.... I'm not sure if It's your timing in showing the schematic with it's real life representation, or your candor and humility, but, I could immediately ID the components in my amp,(as I remembered them) and "follow" what I saw here in that context. I watched this BEFORE I attempted the repair because usually I have to watch videos 10 times with frequent pauses and a hot soldering iron burning daylight. I feel comfortable to start this repair without having to have somebody "hold my hand" from the information I got here.. Thanks
I have a probably identical situation with a Dynacord amplifier and I will try to examine it according to your explanation of this. Thank you very much.
Stumbled upon this video - GOOD JOB! One thing I can suggest - along with working one-handed, use a wooden dowel or chopstick to poke around bitey electronics. A drumstick works as well, until your kid steals it. :D
Googling for help trying to figure out why I've lost my center channel, left back, left surround and right surround channels and came across this. Fixing it myself is out of the question but nice to see that it's hopefully going to be a simple fix. Thanks.
Thank you for your effort...A word of caution though, replacing the defective output transistor without checking its forward bias whether it's within limits or not will allow the audio amp to function again but for more or less 15 minutes only because the transistor will overheat and be defective again.
Like the others before, I enjoyed all of the video. Very clear in presentation and explanation. The weird bit for me was knowing the there was a base, emitter and collector is one thing, but on this type of heat generating transistor, the two central pins that are soldered to the board could be one or the other as I believe the 'base' is part of the chassis/mounting. Thank you for taking the time. The video also has shelf life too! ;)
This may turn out to be practically useful for me; but even if my problem is actually something else, I GREATLY appreciate the time and effort you spent explaining the relationship these parts have to each other and the schematic. Thank you :) I am now far better able to understand what all the forum "experts" I have tried reading were waffling on about. *Note to "experts":* There's no value in explaining something using terminology that only another expert understands, since they already understand it! Take a leaf out of this guy's book. Thanks again TeDubbs. Really. Much love :)
THANKS! Awesome, simplied AND explained why the difference of .5 OHMS exists - I thought I had MOSFETS on my Peavey PV1500, but they are just Bi-Bolar Transistors too.
Not sure if u said it in the video but this is a good FIX and if you want an upgrade on >20Y/O amps you can replace all the capacitors with newer beter ones for better sound
Yeah great video. I like to collect stereo gear, find stuff at garage sales and such. And often you can find something inexpensive, but does have a small problem. Or your cat can knock over a cup of water onto your turned on beloved amplifier and well you know. So I'm getting into learning how to fix the equipment instead of tossing into a land fill. Especially my beloved amplifier/AV receiver which was quite good, and would be expensive to replace with a new amplifier/receiver of the same quality today. Like $1,000 or more.
The two pins for each transistor on the underneath side of the board are the emitter and base connections. Guaranteed. You can still have an emitter collector short and the E-B junction might look OK and fool you with this test. One probe should touch the top metal body (collector) to test for the emitter-collector short.
Mark Z; Yes, you are definitely correct about that! The exact transistors that the amp in this video are using are the typical older style TO-3 metal case packages, and for regular silicon bipolar transistors of this type, (and exactly these part numbers, as seen on the schematic diagram shown, I looked them up in a semiconductor cross reference book I have just to be sure), they have the case itself as the collector, one pin on the bottom is the base, and the other pin on the bottom is the emitter. His test in this case still worked for him because the bad transistors apparently were also shorted between the base and emitter, affecting the readings in the way he showed, however he should have been testing them like you said first. And another thing I have issue with in his test method is using the lowest ohm setting on his meter for this test... Some smaller, less robust, lower power transistors can be damaged by your meter itself if it isn't a high enough of impedance and the meter sends too much current through mainly the base junction, which is more delicate than the other leads of the transistor... That is more of a problem with Mosfets and the "gate" lead, but bi-polars can also sometimes be damaged through the base lead by measuring with too low of an impedance meter... I would have used at least the 2K ohm range on that meter instead of the 200 ohm setting at the very least, and even better yet, use the diode check function to safely test for effective/good junction voltage drop. (A shorted silicon transistor will indicate 0.0V in both directions through a junction that is damaged, and ~0.55-0.6V or so through a good junction one way and open circuit the other way around, (switching the leads around polarity-wise), for each good junction.
Nice to see a reply from a "real" technician. Too many posers on TH-cam. However, a base -emitter junction of a transistor could not be damaged by this (crappy) digital meter. It does not produce the voltage or current (even on the 200 ohm range) to do that; it's limited to about 1 milli-amp tops. Even less likely on a MOSFET. Static electricity would be a more likely potential problem. Lots of old analog meters can produce lots of current, though - I've seen over 150 mA from some with shorted leads on Rx1.
True. I was talking more about the old analog meters. I had no idea what the (admittedly crappy, "Harbor Freight special") meter in this video put out when testing in that way though, so especially with cheap or unknown meters like that I'd start in a higher range with less current output... Better safe than sorry if you don't know for sure... I don't really have to worry about that though, because I always use one of my 3 Fluke meters for testing stuff. I have an older 87, a 189 and a newer 289 model Fluke, so I think I'm good!... I gotta get me an oscilloscope though! I've never been able to afford a good one, and they're very hard to find used too... Maybe I just don't know where to look for one. :(
For audio, maybe look for a B&K 1472 (working with a trace shown) on eBay. They're often under 50.00 plus freight. Very good for audio because they go to TWENTY volts per division. I'm a Fluke nut myself. Wearing a Fluke T-shirt right now in fact. Couldn't tell how many Flukes I own without some head scratching. Let's see. Three original 87's, an 85III, an 87III, 87V, 8840A, 77, re-branded Fluke 23 (Square D brand), a Fluke 12, a 27FM, and a couple "parts cars". That's about it, I think...
I've been waiting for a video like this thank you! Repairing the things you have rather than throwing them out and buying new; is a great thing. People who help others to do this are great people. P.S. If you aren't sure what a boring video is, I can give you some links...trust me, your informative video is NOT boring :)
Current division. Since nobody's mentioned it, that's why those transistors are in parallel. Routing electricity in parallel divides the current. Transistors are rated to both maximum voltage and current capacities. Here, it distributes the current load on each transistor, 25% each. I LOLd at your mention of people getting pissed off because you were talking so much, bu it's not like you spent the first 3 minutes plugging your website or something ;) See other comments about the BCE testing. Good job, great video, great breakdown!
lol i searched to see if someone had already answered before i did, correct you are sir, Parralell in ohms law will show an even voltage drop across each resistor and resistance being no more than the lowest resistor.
Not boring at all u helped me to understand the basics which drive me to want to learn more about what I love to do best for a hobby ..thanks and do more tutorials .
Thanks so much for teaching in such great detail and doing all that research. I am going to attempt to fix the 1 non-working channel on my amp and see how it goes.
Very nice job. You taught me more about troubleshooting than I've learned in any other video. Besides that, the transistor function finally make sense!!! Thank you!
I 100% echo the comment immediately below. You perfectly explained where to check and WHY the resistances varied from 23 ohms down to the 1.2 and 0.7 ohm levels. Showing the resistor values from the schematic and linking those to the resistances that you measured was gold. Thank you for sharing and explaining in such detail!!
excellent video. You didnt use too much jargon, or when you did you explained what it all means. I really appreciate having some help thats explained in laymans terms. Thank you, will tear into my amp now feeling more confident..
Killer info. Have a 12 channel amp that puts out nothing more than the source, like headphone power level. Now I know where to start. You gave me a starting place.
For those wondering why one bank read 1.2 ohms then the bad one was 0.7. Then the other bank was 23 and on at 0.5. The first Bank the transistor shorted but the emitter resistor survived. The second bank the transistor shorted and fried the emitter resistor open. I am guessing that the channels have a bank of four for the positive going signal and a bank for the negative going signal. Which would explain the diode down stream for biasing at the crossover point.
It's a very good video. I love when someone explain something even small details it help a lot to have an idea on that field. Especially when you don't know anything about it. Thank you very much. 👍
thanks. big help. I am just collecting info for a repair I will be doing soon. one channel is NG. I didn't mind you carrying on at all. good info. also I set the playback at 2x speed. fun.
Thanks for the video. I've arrived at the same conclusion, and it's nice to see my logic was correct. Where I'm at now, however, is why did the transistor blow ? Was it just old ? Overheated ? Shorted speaker wires ? Before I go putting in new transistors, I may want to answer this question if I can. Great video, though. And again, thanks.
What steevie-joe said! I have been watching a lot of videos lately on electronic repairs. You made it sound easy for this dummy. Great video. Only suggestion would be to hold pointer still instead of bouncing around. Great camera work, too.
I just got your video feed, I just finished watching it. The best explanation I seen about output transistors. I finished troubleshooting my vintage Sony amp, two bad outputs. Great job.
Excellent video , thnx man. I have a Harman Kardon HK 6600 amp blowing fuses { 2 out of 4 } at power up .I will certainly check the output transistors. Cheers :)
Yeah I will tell you also that if you have an amplifier that is that dirty on the inside you may just want to strip it down and clean it because it’ll do a lot better in the long run than just replacing an outlet transistor
I had a little knowledge of electronics and this video was definitely helpful. Thank you... i know got to put my theoretical knowledge into practice... so bought myself a cheap active speaker to play around with.... i suspect the transistor is gone but will test the resistor if it has one- need to get a hold of the schematic (which is going to be the hardest bit)
perfect video, thank you. ill give it a shot on my bryston 4b, hard to find the transistors as they,re strangly outside the unit covered by some removable metal but your video was a big help.
Don’t even talk yourself down about how this is boring....I came here because I needed some help and you did a better job than any other video I’ve watched and I appreciate your time for that, this video is older but I never needed anything like this until now, but this was easily one of the best transistor-fix videos out there, very, very clear and I learned quite a bit from your video. Thank you
Funny thats basicly what i just told him to right now i didnt see your re$ponse till after but i clicked the like button on your reply as well as the main video
👍
Well said!
Hear hear👍
Fuck the haters!
I am working on an old amplifier, and this is the best information I have found to trouble shoot a dead channel...
Some folks are just good at breaking down complicated thing so others can understand them, it’s a gift 👍🏻👍🏻
The way you explained how a transistor amplifies a signal was spot on.
Thanks for this video, you are a natural teacher ..😊
Just watched one video on fixing broken amps which was useless and longer, then I came here and found what I needed to understand. Thanks a lot. I've been quoted $500 to fix my amp. I could buy a new car for that.
Boy You Rock !!!!! you're naturally informative and clear in your explanation and i agree with the other comments you should be teaching.
Hi, I am very grateful for your video. You may not realise, but you have given some very important information about how things work which are missing in other electronic repair videos. As a hobbyist, I have learnt a lot from you. Thank you.
DUDE!!! Thank you!! I sincerely appreciate your time. I've been trying an hour per day for FIVE months now to figure out how to fix my Pops amp. He passed a couple years back and this thing is pretty much all I have that lets me feel like we're still hangin' together and jammin' ... then it croaked about 6 months ago ... well at least one channel did. I knew it was one of the damned little transistor thingys after watching so many vid's and reading so much, but this was the FIRST one that I actually understood what those 3 stupid leg thingys do and why and how to work forward or back to find the other crap they screwed up along the way, so I can FINALLY rock out with Pops again ... well in spirit anyways ... and ashes too, a bit of em anyways I put in a glass thingy I glued to the top of the sub so he can still dance to the "tight bass response" of his Onkyo he always talked about, whatever the hell that means. I just know it sounds killer when it's working right, and I think I can finally feel comfortable about digging into this little F***er that's been my nemesis for months now. So dear Sir, again, please know that my gratitude is limitless at the moment for you and your valuable time that you've freely shared here .. I truly and deeply appreciate you and your efforts along with your ability to explain it so even an idiot artist completely ignorant of any technical knowledge and skills like myself could understand. It clicked ... and I bet dimes to donuts I kick this things arse now, I just know it!! Thank you SIr!!! ✌️
Wasn't boring at all. I made very good use of it and replaced power transistors on an old, but solid built power amp. So, thank you for sharing.
Very good and clear explanation of how a transistor works and how to diagnose a bad output transistor.
I am very impressed with your skill at teaching something that you yourself had only just learned. We the audience were clueless that you were new at this until you admitted it. Thank you for taking the time to make such a great and helpful video covering a subject that you have obviously discovered that is rarely broached yet needed to be covered.
Sleepy Dragonfly's Fishing Adventures Glad it helped
Definitely, the explanation here on the issue of replacing power transistors will be the best I have ever seen, including some aspects that may be less clear to most people not trained in this activity.
This is one of the best video to simplify a audio amp out transistor thanks a lot u couldn't have made it any easier thanks again all thumbs up love the video
That was possibly the best explanation of the workings of a transisteor and an amplifier I've ever seen in my 5 decades.
Absolutely great video.. you are a natural teacher and excellent at explaining stuff. Thankyou so much .. please make more.. ill bet you’d be really popular if you had a repair channel on here..excellent stuff! Not long not boring always moving forward in a way that makes sense. The transistor explanation was excellent and building from there was very informative .. thx again
That was the best explanation of a transistor I've ever heard! I've been learning about this stuff for several years and never felt I understood transistors as well as I do now. You've earned a sub for that alone
Where you think you talking alot, and making no sense, you've just helped someone who listen alot to music but couldn't tell you why something has blown, and now I'm using TOUR knowledge you've shared to go and tackle a crown xti amp, that starts up then shuts down!!!
So THANK YOU
Thanks for posting this!
Before I watched this, I’d never considered pulling a bad transistor and the amp will still work, albeit with less power output than before, but the point is, it’ll still work!
I tried it on a vintage BGW amp I have with a blown channel, and transistors made of unobtainium, and it worked!
I removed the same transistor from the opposite side, even though it was good, so both channels would have equal output, and Shazam! An amp that hadn’t worked in 20 years was back in service! THANKS again!😉😎👍🏻
christopher fogarty lols if you’re just pulling out transistor that is fine but if you have a bad one it will not work basically if you pull the bad transistor it may work just like what you did
I think the first thing I would do before any thing else is to blow out all the dust and dirt. Quite often overheating is the issue leading to blown transistors. Air flow is very important if the amplifier is driven hard. Once fixed any air filters should be well cleaned, check the fan, apply a little oil if needed. If you don't do this, it will probably blow up again.
You're absolutely right. I wound up going back in and blowing it out after I replaced the transistor. This one blew after it melted a 1/4" instrument cable which was connected instead of a proper speaker cable, but I doubt the excessive dust helped things.
Won't hurt to clean it!💯
@@donaldcatlett5850that's what he said.
The lights just went on. This is the first time that I’ve literally understood how a transistor or indeed an amplifier works. Well done and thanks.😮😊
Dude. You definitely did not make a fool out of yourself. Your explanation put me on the right path for me trying to fix my reciever. It is not the same but it works the same. Thank you very much. You rock!
You measured the Emitter and Base. Your Collector-Emitter idea is correct, but this time you got lucky with your diagnosis.
Brother, you brought back memories of my High School Electronics classes, and you're probably better at electronics than I am. Ill tell you one thing tho. You refreshed my memory on the transistor and resistor topics. So thank you for taking the time to make this.
Dude, I am extremely thankful that you put this video together!! I have a similar issue but I have just started down this long and dark path that lead me down to a rabbit hole I couldn't help but dive into! I have a board that keeps blowing a fuse on a bass amp that I don't have any of those round guys that you were showing I have these square ones that are on an aluminum plate and I want to say that they're bridge transistors, but I am not sure but there is solder missing on a couple of the points and I wanna say that is the problem. But I'm just not sure.
I loved this video!!! I watched it right to the end and I learned a lot. I am a newbie at this field but dabbled with it a long time ago. I have the same amp, it's great a real work horse. You are a really good teacher and I hope to see more of your videos. You have a knack of explaining things that keep me and hopefully others focused to the job. Thanks again and take care.
When I brought my amp in for service I mentioned that it was blowing fuses. The tech just said "Probably a transistor". He was right and it cost me $85. Your video explains perfectly how he would've known what was wrong and now I have a bit more knowledge. Thanks!
Just FYI, that’s not a “1” on the multi-meter. It’s an “L”. Some meters will say “OL” which stands for “out of limits”. Means the resistance is outside the limits you’ve chosen to test because the two probes aren’t actually being connected through anything - cuz the fuse is blown. If a connection is made between the two probes THROUGH the fuse it will show the value of resistance in the object that’s being used to bridge them together.
Good video.
it's a 1 on his meter. his meter doesn't display letters.. only numbers. But 1 on his meter means the same as 'OL' on your meter. not all meters are made the same.. different displays..some are alphanumeric, but the he's using is numeric. it displays and communicates the same information though, so he was reading it correct. 1 shows there is resistance. good fuses will show continuity..just like he said.
sometimes I don't understand why people feel the need to "correct" things that are not wrong..
Excellent Video ! Like you I have searched hours to try and find enough info to try and track down faulty components in an Amp. Most of the ones I have found assume that you are already something of an electronics expert, so don't give such a good and detailed explaination as you have here. Can't praise you enough, but my thanks.
Hey thanks! This video was actually super helpful. I've been wanting to get into fixing electronics for a while so I went and got myself a gig fixing amplifiers and speakers for a local pawn shop today. I have no clue what I am doing and I like the way you explain things and it wasn't boring at all!
I watched several videos on fixing electronics and this is hands down the best one yet. So much valuable information. Spoke in plain english, not some text book confusion. Thank you!
I can't imagine this has not been pointed out yet but the solder pads on the board connect to the Base and Emitter. The Collector is the big metal case on the other side. On this model QSC amp the collectors are grounded directly to the aluminum heatsink. Most amps isolate the collector with an insulator, some of which require thermal transfer compound, others do not. It is also quite common for other components to short (or open) along with the power transistors. While I understand that you are trying to help people out and save them money, you are in effect giving them just enough information to possibly do serious damage to their amp or to themselves in the process. It isn't always as easy as it looks folks.
Seriously thank you thank you thank you more times than I can say. I’ve had my kenwood stereo system for so long and the power amp recently ‘shut off’ ( no signal lights or sound going to speakers) and if not for the video I would’ve have had to spend 100+ on a new one or having someone else repair it so again thank you so much dude. 5 years later and literally your still the only video online I can find that explains this in a way someone who grew up just doin it myself and not knowing professional terminology can understand 😂😂
Driving a speaker load with a guitar cable is always s bad idea. Good clarity on your explanation of tracing out the faulty output transistor.
Did you know that dust becomes conductive after heat and current flow hit a trigger point? That sends the DC rail voltage where it should never go...avalanche voltage breakdown followed by shorted output devices.
Clean away the dust and check the mica wafer for cracks. Replace the wafer if it looks compromised.
Dude that was the most comprehensive amp repair I've ever seen Outstanding
Very good presentation and explanation of the circuitry. I've dabbled with electronics about 40 years ago and you brought back memories of those days. Thanks
Awesome vid .. I have a QSC PL9 and one of the channels stop working. I was about to bring it for service and like you already know, it is an outdated AMP which would cost me $$$$$ then who to tell, similar issues can resurface again ... knowledge is POWER. Thank you for such detailed vid for DIY like myself ... you just saved me $$$$$$$ for now :)
Buying a new stereo amp is difficult today, all you find are 5.1 and up surround amps with more than two speakers, so repairing my Sherwood receiver was my best option, I found thst it uses a combo of B1560/D2390 transistors, I found a set of 5 pairs on e-bay for less than $15.00, this vdeo was very helpful in finding the fault quickly, thank you.
I'm far less knowledgeable than you are, but wasn't totally lost. Thanks for the help. I'm here because I have several 70s receivers that have problems. Most all don't put out sound from the right speaker, across all channels. So, no stereo but I can play both speakers if I use 2 channels. Your video was the first to explain what was wrong(I guessed correctly, but didn't know the terms), why and how, and also explained how to fix it as well. Thanks a million!!!
If you have time, I have more questions so I don't ruin a couple really nice amps, or rather "stereo receivers"... I have a 1970 Kenwood kr-6160, and my favorite and cult following unit, the 1976-1979 Sansui 9090db. A few others of the Era, but these are my favorites.
I like that you literally explain what the difference is of each channel was and where that that break comes into I didn't really fully understand the admit her the bass and The Collector and what the percentage of them actually working is until you fed me this information I think you would be an excellent teacher for anyone
I think you would be an excellent teacher for anyone to learn things from and I do appreciate you
while i was listening to your video i was fixing a jb systems vx400. or trying to fix it. i'm no electronics guy. it is because of guy's like you that i can learn how to fix things !!! thank you very much !
Man this is the way I wanna be taught!! By a guy who learned it himself and can explain it in simple language. This was great. Pretty sure thats what I got going on here. Not sure Im gonna do it myself yet. Not the best with a solder gun But I really wanna learn this stuff and your explanation was great. Just like everybody else said great job.
Excellent video ! Like you i've done a lot of searching to get enough info to track down faulty component(s)i in an Amp. Most of the ones I have found assume that you are already something of an electronics expert, so don't give as good an explaination as you have here. Can't praise you enough.
Will give this a try. Whether or not it works to diagnose if one or more output transistors is blown on my amp, I learned useful info. Thanks much. Great video.
Awesome! Thanks for the video. I've always been interested in electronics, and unfortunately did exactly what you said not to do. I replaced a fuse and turned my amplifier back on. I have a Mackie M2600. When I went to turn it off, I didn't hit the switch all the way. It shut off for a split second, and came back on. It tripped the breaker in the basement. When I turned it back on, it powered up for about 6 seconds, and then the fuse blew. I never had any problems before, and knowing it was a slow blow fuse, I ASSumed that was the only problem. After replacing the fuse, it powered back up and stayed on, but when I went to put power to it, the "protect" and "short" lights lit on channel 1. It was fine at low volume, but given some power, both lights lit up. From what you explained in the video, and what I've experienced, I'm guessing a short between collector and base - and who knows what other damage it may have caused! Looks like I'll be taking this one to the shop, but the video was still very informative, and I now I know what a transistor does!
Bro! Best germanium amp fixing video on TH-cam, not long nor boring, exactly what one is looking when trying to troubleshoot and fix one of these things. Thank you very much for taking the time and effort of doing this for all of us! Cheers!
You did good, I understand more now then I did before, you explained it very well in layman terms, thank you for your time.
Thanks brother. I knew nothing about this circuit diagram but now I understand something new. Thanks for teaching me.
That was an excellent video and a fantastic explanation. I have instrumentation background and an electronics degree. I also own a DJ company and have always sent the amps back to manufacturer to be repaired due to time constraints. i have so many amplifiers that need replaced that i am going to fix them myself. This was a great quick troubleshooting video. Well Done!!!!
Thanks for a very quick and simple explanation. Easy to understand and very helpful!
I agree w/ @stevie-joe.... I'm not sure if It's your timing in showing the schematic with it's real life representation, or your candor and humility, but, I could immediately ID the components in my amp,(as I remembered them) and "follow" what I saw here in that context. I watched this BEFORE I attempted the repair because usually I have to watch videos 10 times with frequent pauses and a hot soldering iron burning daylight. I feel comfortable to start this repair without having to have somebody "hold my hand" from the information I got here.. Thanks
I have a probably identical situation with a Dynacord amplifier and I will try to examine it according to your explanation of this. Thank you very much.
Stumbled upon this video - GOOD JOB! One thing I can suggest - along with working one-handed, use a wooden dowel or chopstick to poke around bitey electronics. A drumstick works as well, until your kid steals it. :D
Googling for help trying to figure out why I've lost my center channel, left back, left surround and right surround channels and came across this. Fixing it myself is out of the question but nice to see that it's hopefully going to be a simple fix. Thanks.
Thank you for your effort...A word of caution though, replacing the defective output transistor without checking its forward bias whether it's within limits or not will allow the audio amp to function again but for more or less 15 minutes only because the transistor will overheat and be defective again.
You helped me fix my Sansui 881 and saved me hours! Thank you!
Like the others before, I enjoyed all of the video. Very clear in presentation and explanation. The weird bit for me was knowing the there was a base, emitter and collector is one thing, but on this type of heat generating transistor, the two central pins that are soldered to the board could be one or the other as I believe the 'base' is part of the chassis/mounting. Thank you for taking the time. The video also has shelf life too! ;)
This may turn out to be practically useful for me; but even if my problem is actually something else, I GREATLY appreciate the time and effort you spent explaining the relationship these parts have to each other and the schematic. Thank you :)
I am now far better able to understand what all the forum "experts" I have tried reading were waffling on about.
*Note to "experts":* There's no value in explaining something using terminology that only another expert understands, since they already understand it! Take a leaf out of this guy's book.
Thanks again TeDubbs. Really. Much love :)
very good accurate basic description. nice. -- the last part that analyzes the circuit is very good
Thanks much for that mini-lesson. Having the correct schematic for the unit being repaired sure is helpful. Thumbs up.
love the small talk i really understand whats going on the way you tell it.
THANKS! Awesome, simplied AND explained why the difference of .5 OHMS exists - I thought I had MOSFETS on my Peavey PV1500, but they are just Bi-Bolar Transistors too.
Not sure if u said it in the video but this is a good FIX and if you want an upgrade on >20Y/O amps you can replace all the capacitors with newer beter ones for better sound
Yeah great video. I like to collect stereo gear, find stuff at garage sales and such. And often you can find something inexpensive, but does have a small problem. Or your cat can knock over a cup of water onto your turned on beloved amplifier and well you know. So I'm getting into learning how to fix the equipment instead of tossing into a land fill. Especially my beloved amplifier/AV receiver which was quite good, and would be expensive to replace with a new amplifier/receiver of the same quality today. Like $1,000 or more.
The two pins for each transistor on the underneath side of the board are the emitter and base connections. Guaranteed. You can still have an emitter collector short and the E-B junction might look OK and fool you with this test. One probe should touch the top metal body (collector) to test for the emitter-collector short.
Mark Z; Yes, you are definitely correct about that! The exact transistors that the amp in this video are using are the typical older style TO-3 metal case packages, and for regular silicon bipolar transistors of this type, (and exactly these part numbers, as seen on the schematic diagram shown, I looked them up in a semiconductor cross reference book I have just to be sure), they have the case itself as the collector, one pin on the bottom is the base, and the other pin on the bottom is the emitter. His test in this case still worked for him because the bad transistors apparently were also shorted between the base and emitter, affecting the readings in the way he showed, however he should have been testing them like you said first.
And another thing I have issue with in his test method is using the lowest ohm setting on his meter for this test... Some smaller, less robust, lower power transistors can be damaged by your meter itself if it isn't a high enough of impedance and the meter sends too much current through mainly the base junction, which is more delicate than the other leads of the transistor... That is more of a problem with Mosfets and the "gate" lead, but bi-polars can also sometimes be damaged through the base lead by measuring with too low of an impedance meter... I would have used at least the 2K ohm range on that meter instead of the 200 ohm setting at the very least, and even better yet, use the diode check function to safely test for effective/good junction voltage drop. (A shorted silicon transistor will indicate 0.0V in both directions through a junction that is damaged, and ~0.55-0.6V or so through a good junction one way and open circuit the other way around, (switching the leads around polarity-wise), for each good junction.
Nice to see a reply from a "real" technician. Too many posers on TH-cam. However, a base -emitter junction of a transistor could not be damaged by this (crappy) digital meter. It does not produce the voltage or current (even on the 200 ohm range) to do that; it's limited to about 1 milli-amp tops. Even less likely on a MOSFET. Static electricity would be a more likely potential problem. Lots of old analog meters can produce lots of current, though - I've seen over 150 mA from some with shorted leads on Rx1.
True. I was talking more about the old analog meters. I had no idea what the (admittedly crappy, "Harbor Freight special") meter in this video put out when testing in that way though, so especially with cheap or unknown meters like that I'd start in a higher range with less current output... Better safe than sorry if you don't know for sure... I don't really have to worry about that though, because I always use one of my 3 Fluke meters for testing stuff. I have an older 87, a 189 and a newer 289 model Fluke, so I think I'm good!... I gotta get me an oscilloscope though! I've never been able to afford a good one, and they're very hard to find used too... Maybe I just don't know where to look for one. :(
For audio, maybe look for a B&K 1472 (working with a trace shown) on eBay. They're often under 50.00 plus freight. Very good for audio because they go to TWENTY volts per division. I'm a Fluke nut myself. Wearing a Fluke T-shirt right now in fact. Couldn't tell how many Flukes I own without some head scratching. Let's see. Three original 87's, an 85III, an 87III, 87V, 8840A, 77, re-branded Fluke 23 (Square D brand), a Fluke 12, a 27FM, and a couple "parts cars". That's about it, I think...
BTW the BK 1472 is only 20mHz. All you need unless you are working with FM front ends...
Thank you for this detailed explanation. I'm currently debugging a jukebox amplifier, and this has given me some good insight on what I need to do.
Exlnt video mate, This a great primer for understanding transistors and looking for something other than a blown cap.
That is the law of subtraction in finding faults, easy and fast without too much technically stuff.
Thanks, I learned something and I haven’t seen any showing this before, something I wanted to understand for a while now. So, kudos!
I've been waiting for a video like this thank you! Repairing the things you have rather than throwing them out and buying new; is a great thing. People who help others to do this are great people. P.S. If you aren't sure what a boring video is, I can give you some links...trust me, your informative video is NOT boring :)
Current division.
Since nobody's mentioned it, that's why those transistors are in parallel. Routing electricity in parallel divides the current. Transistors are rated to both maximum voltage and current capacities. Here, it distributes the current load on each transistor, 25% each.
I LOLd at your mention of people getting pissed off because you were talking so much, bu it's not like you spent the first 3 minutes plugging your website or something ;) See other comments about the BCE testing. Good job, great video, great breakdown!
lol i searched to see if someone had already answered before i did, correct you are sir, Parralell in ohms law will show an even voltage drop across each resistor and resistance being no more than the lowest resistor.
Not boring at all u helped me to understand the basics which drive me to want to learn more about what I love to do best for a hobby ..thanks and do more tutorials .
that's the dirtiest amp I ever saw, but good job explaining this man, appreciate it!
Easy to understand straight to the point great vid
Thanks so much for teaching in such great detail and doing all that research. I am going to attempt to fix the 1 non-working channel on my amp and see how it goes.
Very nice job. You taught me more about troubleshooting than I've learned in any other video. Besides that, the transistor function finally make sense!!! Thank you!
Thank you for taking the time to create this clear and simple explanation. It helped me. Kudos.
I 100% echo the comment immediately below. You perfectly explained where to check and WHY the resistances varied from 23 ohms down to the 1.2 and 0.7 ohm levels. Showing the resistor values from the schematic and linking those to the resistances that you measured was gold. Thank you for sharing and explaining in such detail!!
excellent video. You didnt use too much jargon, or when you did you explained what it all means. I really appreciate having some help thats explained in laymans terms. Thank you, will tear into my amp now feeling more confident..
An amazing insight into what goes on with a fault in a Amp, very valuable info, most grateful.
Thanks Most well explained (in simple terms) video I came across so far on this topic.
Killer info. Have a 12 channel amp that puts out nothing more than the source, like headphone power level. Now I know where to start. You gave me a starting place.
Any luck ?I'm having same problem with my amp..
For those wondering why one bank read 1.2 ohms then the bad one was 0.7. Then the other bank was 23 and on at 0.5.
The first Bank the transistor shorted but the emitter resistor survived. The second bank the transistor shorted and fried the emitter resistor open.
I am guessing that the channels have a bank of four for the positive going signal and a bank for the negative going signal.
Which would explain the diode down stream for biasing at the crossover point.
It's a very good video. I love when someone explain something even small details it help a lot to have an idea on that field. Especially when you don't know anything about it. Thank you very much. 👍
Hey man keep it up I can actually understand what you were saying. Keep learning so you can teach me more thanks a lot
thanks for explaining this video so well. been trying to understand Amp circuits and how amps work and your video was by far the most helpful
thanks. big help. I am just collecting info for a repair I will be doing soon. one channel is NG. I didn't mind you carrying on at all. good info. also I set the playback at 2x speed. fun.
Thanks for the video. I've arrived at the same conclusion, and it's nice to see my logic was correct. Where I'm at now, however, is why did the transistor blow ? Was it just old ? Overheated ? Shorted speaker wires ? Before I go putting in new transistors, I may want to answer this question if I can. Great video, though. And again, thanks.
Great video, thank you for sharing. You have made the world a smarter place
What steevie-joe said! I have been watching a lot of videos lately on electronic repairs. You made it sound easy for this dummy. Great video. Only suggestion would be to hold pointer still instead of bouncing around. Great camera work, too.
Buddy you should be a teacher. Very knowledgeable and nicely explained
I just got your video feed, I just finished watching it. The best explanation I seen about output transistors. I finished troubleshooting my vintage Sony amp, two bad outputs. Great job.
Wow thank you you explained that very well I've now fixed four of my blown amps cheers buddy. 👍🍺
Excellent video , thnx man. I have a Harman Kardon HK 6600 amp blowing fuses { 2 out of 4 } at power up .I will certainly check the output transistors. Cheers :)
I really like that you took the time to explain all this. Great video.
Yeah I will tell you also that if you have an amplifier that is that dirty on the inside you may just want to strip it down and clean it because it’ll do a lot better in the long run than just replacing an outlet transistor
I had a little knowledge of electronics and this video was definitely helpful. Thank you... i know got to put my theoretical knowledge into practice... so bought myself a cheap active speaker to play around with.... i suspect the transistor is gone but will test the resistor if it has one- need to get a hold of the schematic (which is going to be the hardest bit)
Great, useful straightforward and concise explanation. Awesome dude!
Thanks for this video,at last safter a lot of searching ,s omthing in depth and useful. I have learned a lot .
perfect video, thank you. ill give it a shot on my bryston 4b, hard to find the transistors as they,re strangly outside the unit covered by some removable metal but your video was a big help.
I tried to check the numbers and they were all over from 193.2 to 0.1, would you have idea for this? even my good channel had numbers all over.
Great informative video tutorial. I just wanted to see the major failure of a class A/B amplifier.