The Sort of Repair I Usually Reject - Solid State Acoustic Amp, Full of ICs, No Schematic
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- เผยแพร่เมื่อ 15 ก.ย. 2024
- It's never fun opening up an amp full of Integrated Circuits (ICs) without a schematic. But here goes... let's fix this Dean Markley KVC-60 Acoustic Guitar Amp...or at least attempt to.
Note: hidden within today's video is a numerological message to my Masonic brethren. When the time is right, you'll know what to do.
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I love the fact ive been watching you so long i can watch a video from 6 years ago like its brand new. Such a wealth of info throughout the Guitologist library. Thanks Brad! You still continue to inspire and inform me each and everyday! Started watching you in 2015! Thank you my man!
Holy shit, you sang that like you wrote it!!!! You never fail to impress the hell out of me Brad!
Totally agree! Awesome job Brad!
If the lights are super bright, one thing you can try is to turn them around and have them reflect off the walls or ceilings. You can put some white paper or foam core up to help the reflection. You get softer and more diffuse light, which might be more comfortable and better for shadows. Kinda works like a big softbox but more convenient.
Oh no! Another bad solder joint. I ran into my first today. A garage sale garage door opener for $30 . Intermitently shut off so i hit it w ith a paddle when it fails and has worked for the last 9 months. Now that weather is better took a look at it. Nothing visible but pushing on circuit board made it work. I suspected the connector and cleaned and bent pins to no avail. Gave up and reflowed all larger solder joints ( for relays and connectors ). There was no sign of a cold solder joint but now works perfect. I never would have done that except for all your bad solder videos. Thanks for the good show
Dude, a million thumbs up for the song at the end!!!.... U did Jim proud my brother!..... Loved it man!
I was a dead Indian in a past life.
and Robby!
The Guitologist ....awesome response man!.... Funny shit!
Sounds good. You can usually figure out those iCs if you're lucky enough to find the number still legible on them. You can then look up what voltage belongs on what pin. Also you can check how hot they are on the surface to get one more clue. (Knowing Brad knows this, for the viewers.)
Nice agressive Doors cover !!!!!\m/!!!!!
Took my Peavy Backstage Plus 35 W Amp apart - cleaned the circuit board (QTips soaked in liquid soap + water) - looked at all solder joints - applied a few drops of liquid flux / resoldered four (4) joints holding the Guitar Input switch to the circuit board + bent in the metal tip part of the switch to make sure contact happens when guitar cable is inserted. Resoldered one of three wires from the transformer to the board. Fixed!!!!!! Including Spring Reverb!!! Thanks for making this video!! Good aggressive Doors Jam. Still might need a new switch but at least it works!!
I have been doing work for a consignment music store here in town and this type of gear is 90% of what I repair. Not near as fun as the old tube amps but it does force you to get creative with troubleshooting since schematics are almost always unatainium.
dlunsford1980
For what it's worth, Brad, I enjoyed the hell out of this video. "Love me two times", was spot-on, and a great bonus!
I'd have probably completed the repairs in much the same manner that you did, boxed it up, dragged it to the UPS shipper, then turned around after deciding that (under an anal-retentive impulse) I needed to build and install a custom wiring harness, and add a new set of Eminence speakers, and Radian horns, and while I was at it, juice the outputs a wee bit (I didn't know that they manufactured semiconductors in Morocco).
Then I'd have lost my tail on that repair!
For two years, '78, and '79, (and maybe a little of the way into '80), Weller -- Xcelite made a set of nut drivers (5/16 thru 11/16) for potentiometer removal and installation. They were equipped with really high-end Silastic seats for the shafts, and a 1-ounce tube of silicone conditioner for the seats. They were $35.00 per set (pricey), but surely would have come in handily with this project.
There's something about the chords at the turn that slay on this song - and you nail it.
Nice job chasing those circuit board gremlins down. Love hearing the acoustic playing and great tribute to Jim.
Dig the new mic setup! Sounds good. Headphones on boys!
Watched several of your vids and you're very knowledgeable, but seeing you perform shows where your heart is at and where your inspiration really comes from, very cool. Cant say this about too many youtubers but I rang your bell. =)
Hey man, thanks for the video. It helped me identify a pair of circuit boards I received in the box with my Fender Cyber Twin chassis. The previous owner thought they were from a Marshall. They are identical to the boards in that Dean Markley. Mystery solved.
Very good Brad..!! That electronic microscope has opened a new avenue in problem solving.! Love The Doors... didn't know you were the second coming of Jim Morrison..!!
Actually, I was Jim Morrison. Don't tell anybody. I don't want to be hounded by groupies.
Ha! That was super interesting! I dig the microscope! Love Me TWO TIME LONG TIME! I'd advise them to replace those crazy speakers!
Dude, never mind your repair ability, great cover of the doors!
Even it's an old vid, i luv it. Still have that same Amp sitting somewhere.
I also own a Dean Markley K75 guitars Amp, wich was one of the best designed Sud State amps back in it's time. Dean Markley made some real well made stuff, way ahead of the Fender solid state amps back in the early 80s, i still have it as a kind of backup and it takes pedals well.
Your stuff just keeps getting better and better. You should totally have a Patreon account. You don't even have to promote it, just have it there. You content is easily worth a dollar an episode.
just today i opened a customer's (bad audio) Bogen GS-100D amplifier ... it's not only all ICs, but they're of the SURFACE-MOUNT variety!
Glad i'll be retiring next year.
Sometimes when you are doing some shredding on electric after a repair, I'm thinking....Bradley Govan...
Lately with the acoustic and singing your just deadly.
Tons of Canadian bush love to you brother.
haha..."Bradley Govan" made me laugh. that dude is on another planet.
Lol, I know but sometimes your legato shred is pretty effing amazing man!
I think I could use me some of that "Canadian bush love".
Oh buddy. You better take your wife camping one summer up here. Bring her back to a commonwealth country and the bush love will be unstoppable
Love the Doors and the flashbacks they bring, great song choice Brad! I don't know who Bradley Govan is and you totally lost me at Canadian Bush Love!! But I ain't picky i'll take em bushy or bushless LOL
The chips are likely to be operational amplifiers (op amps) in analog filter circuits.
and that is why the lizard king never really died.. loved it mate,, made my day.... encore, encore. keep well dude
I have a Dean Markley combo. I like it a lot for a solid state amp. This amp when working must sound good. If I saw this amp, it would be an easy sell. Man, I love this channel! Thank You Brad!!!
Hay Brad, I love watching you videos . they take me back to 1969 , when I was repairing and building guitar amps. growing up, my room was nothing but guitars and electronics. funny you do things almost the same way I did. you do need a set of nut drivers, lol. now I mostly build and repair guitars and condenser mics. still love tubes. good work, thanks steve
all right Brad you got me laughing off my rocker. lol. rather well done for an ol tune i was delivering papers to door steps when that one hit the charts.lol
Very cool Doors rendition!!
I don't think he stopped to check if the last phrase was in his (non-falsetto) range or not before he started, though. I don't think his throat appreciated that very much.
Ahh Dean Markley amps! I remember testing them out at my local music store when they first came out. I remember the 60 and 120 watt tube heads sounds pretty good. They pushed them pretty hard for a while then they just faded away.
I don't remember the tube heads.
I think Sammy Hagar used them for a bit.
Jim Morrison is alive! Nice troubleshooting video without documentation.
Hahaha like that huh? Maybe one day ill show the video of me in my high school days impersonating Jim at a poetry slam! 😂
chorusing white noise is so beautiful.. should definitely use on my new post metal album...
That looks like a 22 bird shot round!
I was an auto electriction 17 years have seen live rounds in fuse boxes before.
Fun when you have a repeat bad short.
Love your videos. Keep it up!
From Doug
I'veopened up a 76 watt Line 6 Spider 3. The customer bought it and put it away after it died in 45 seconds. He forgot about it and couldn't take it back under warranty. The power dies to the preamp otherwise it works fine as new. I'm taking out the chopsticks. there is no other way to tell what is failing with it.
I should have typed 75 watts. It was late and in the dark. The solid state amps are a good source for speakers and new cabinetry. Most are junk.
Great video Brad!!!! The content balance of technical amplifier work and then a performance to match the style of amp that's been across the healing bench. Superb!! Big love from John in London, England.
how was the speakers wired series parallel? mabe it was wired wrong with the ohmage too low pulling 2 much current blowing the fuse??? cheers brad ;-p
Series parallel, yes. The end result should have been 8 ohms total. Doubt that was the issue. But nice thinking!
2:23 "for your coffee-house gigs or whatever"... exhales conspicuously....
*snaps*
Brad live at The Bench. We need a DVD!
Looking for an open guitar case where I can toss in a dollar or two. Good performance at the end!
Well, sounds like you nailed it. Hopefully that does the trick. I enjoyed the microscope portion of the show.
still loving the vids, you've really upped your game with the new equipment, i like it :D
You should use a solder-pull it to take off the cold solder and apply new...
Love the titles at the end for "Love Me Two Time" and "Washburn Dumpster Guitar".... and a great cover of the song!
Keep up the goodly work!
5 thumbs up for the performance Brad!
Hi from England, go on son, make em have it.
Now , see this is the start of a ton of acoustic electric guitars hitting the market in 90s ...and for an acoustic player who didnt know much about amps anyway, this looked like a pretty fair deal... 25 years later we know better
Loving the microscope setup.
I don't envy you for diving into this one. Whew!
Also didn't expect that rear speaker on there. Reminds me of the passive radiators on the backs of some old Klipsch stuff.
Love that “fuse”, and I thought gum wrappers were bad. Sheesh
What was that strawberry jelly you put on the pot solder joint ~19:08? Lights, mic, and microscoped monitor make big improvements. Looks/sounds good!
Thanks for the feedback. Constantly trying to improve. I'm my own worst critic.
Ignore my last.......didn't notice after a while and the sound quality varied as you moved around and change angle etc. Enoyed this one, especially the microscope.
I hadn’t thought of that in years, but every house I lived in until I got married had a fuse box. Some were glass screw ins, the larger amp fuses were like 12, gauge shotgun shells that were brasses on both ends... the 220 outlet seem to use a pair of those
Thanks for the video, Brad! The Doors cover was really cool. But why does everything sounds like it's being recorded with only the camera mike? Both your guitar and your voice sound really roomy, even though I see the microphones are placed really close. I have noticed it even back when you started to mike up the amps and it bothers me a lot.
Well-spotted. Although I captured the audio from that mic on my laptop, I did not use it in the final edit because it was unfortunately distorted. I've replaced the mic for future videos. Bear with me, I'll get it right eventually.
@@TheGuitologist Turn the gain on your recorder WAY down. You can normalize the volume using Audacity (or whatever audio editing software you care to use) without having to use compression/limiting on the source. Trust me - you'll love never having to worry about recording too hot and inducing distortion into the recording.
Ahhhhhhhhh, The Lizard King Lives in Brad’s basement. That was bitichin. Thanks for posting the vid. Curtis
You might want to put the came in front of the screen when showing microscope footage (a more preferable choice would be capturing the output of it). All the glare caused by the lighting made hard to see what you were doing.
Also...This amp apparently has spring reverb. When you opened it, there were two rca cables connected to a sealed box below the speakers.
The microscope is a nice one, but one thing it doesn't do is output HDMI to a monitor and capture video at the same time. It's a bummer, but I can work around it. Just need to reposition some lights when in use.
your full of surprises.. I enjoyed that very much..
Hey Brad, I got a solid state question/problem... I've got this Marshall Valvestate VS100 Head & it sounds great/does what it should until you stop playing.. When you stop playing & let the audio fade out naturally there's this weird subtle sizzling sound that occurs towards the end of the sound breaking up, it's really evident when using the headphones & it's happening across all 3 channels.. This VS100 is from 1998 & it used to belong to a death metal guy so I can just imagine that its spent most of it's life cranked up to 10 which makes me think that one of the IC Chips have been overdriven to the point of needing replaced.. I've replaced the tube & nothing changed so now I'm trying to figure out where the source of this noise is coming from.. According to what I've managed to dig up online, this VS100 has a circuit that involves 5 IC Chips from Input to Output & that's where I suspect the problem is but I can't seem to confirm that as being the case.. As I mentioned before, this amp sounds great but this sizzling sound at the very end of the audio fading out is not normal.. Any suggestions or explanations of how the IC Chips function in a guitar amp would be greatly appreciated..
might I suggest a nutdriver or deep socket for the pot retaining nuts? I guess the knobs will cover the scratches to the faceplate.
Hell yeah. Excellent cover doors one of my favorite bands
I'm a little surprised the added speakers didn't create an issue. One thing solid state amps have very little tolerance for is a speaker impedance that's lower than the amp's minimum. A number of stereo amps I fixed was due to the owner adding speakers to their setup. The two Pyramids are 8 ohms - which is fine if the amp can handle 4 ohm.
Question, I'm I'm tearing down an old tape deck from the 70s and I plugged it in to see if it worked and I wonder if I need to discharge something before I go putting my fingers on stuff? Thanks.
haha, the doors thing rocked.
Dude.... You've got a great voice
Thanks man. It does alright for most rock stuff. I doubt I'll be winning any TV talent shows with it, but who cares about that anyway.
Brad the Guitologist & the Solder Joints. (if you ever need a band name) Thanks for all your videos. I always look forward to SPF vids ...It'd be great if you started BS Hump-day vids.
Maybe for an encore, brad can play "The Unknown Solder" By The Flux Capacitors
Brad and the BAD Solder Joints
I know this will probably sound stupid but why are tube amps preferred over solid state?
I have seen alot of stupid things put in fuse holders, but actually fabricating a metal rod for it is a new one for me.. Why go through all that trouble instead of just replacing the fuse?
Loving the microscope.!
A repair and a tune. Nice.
Went rescue mission/goodwill shoppin. Good idea! More electronics than you can shake a stick at!
Nice! What did you get?
The Guitologist a white lamp 😂
Well worth watching if only for the version of Love me two times! Thanks Brad.
Good day. Thanks for the great videos. Constructive feedback, maybe keep the blinding work bench light off when the camera is on you and your workspace. I still see spots 😊
You rock! Come back and tell us how the extra speakers were wired?
Probably a dumb question, but why do you slowly bring the voltage up with a Variac? I would think that would cause problems in the same way a power fade might damage modern electronics. Working with medical electronics - I might use a Variac to perform calibrations, but maybe it's because you are servicing analog devices vs digital - I like the video microscope to examine solder joints, that's great!
older kustom amps...wav212 specifically...would you be interested in taking a look at it?
There's no escaping the youtube rabbit hole once Doors mode has been activated.
Awesome !!!...................Love your channel !!.....Great singer by the way !!
Love hearing me some Morrison. The dumpster special turned out pretty groovy.
Headstock's still hanging in there!
Awesome repair video Brad!..but I don't think I seen/or missed where you checked to see if the impedence was correct with that extra speaker/s that they had cobbled together.
It was correct when I put it back. I believe it was correct when I got it too. Looked like a dog's breakfast, but worked as intended, I guess.
The Amp God strikes again!!! Agree on the Doors Cover!!!
Brad, I really enjoyed the video (as I always do), I have an recording studio and let me suggest a Rode tube mic. The NT-1 is very good and it won't break the bank either. It is under a grand, around 600. or 700. and it is what your looking for bro. Good job on the song. I'm not a big Doors fan but I really liked your version of it. Take care... Jeff G.
The scratches probably came from manufacturing, piling all of the boards together in a loose box 25 or 30 high and sending them on a wild fork lift ride somewhere. Personal experience.
Do you do any work on pedals? I have a Tech21 Bass Fly Rig and the Octafilter section on it has pooped the bed. Like, it's farting out any time I engage it. Sounds terrible and the unit is out of warranty.
she's a good producer! nice tune......
I had fun sitting in the pot and playing triplets along with your love me two times rendition! Densmore triplets are always a blast.
Dude why are you not doing guitar covers on TH-cam? I love your content and would watch your covers whenever you put them out. Killer doors cover man!
I put a bunch up when I first started doing YT. No one ever watched them.
Ahh Dean Markley Blue Steel's! I kept buying them because they came with sticker. I'm a simple kind of man.
I've bought a ton of their acoustic strings.
Brad can you help me figure out the best way to bias my super reverb reissue? i got a pair of matched nesstubes . I also have a quad of 6L6's for a Traynor CV80 that have 5881's in it now . i had replaced them with the matched quad and in three min. two started red plating. popped the 5881's back in and have't had a problem. I thought i could get away with it for it's self biasing but i suppose one for the tubes it s oridginally biased for . . theres very little id on these chassis or frames. that even suggest ab whatever. would love to find a scepmatic for these guys. would appreiciate any suggestions. t hx.
Man what a Great Voice !! Love it
I enjoyed the Doors at the end!
25:06 ist that glue to hold the 5W resistor down? Almost looks like it is leaking from a crack in the resistor
@The Guitologist I've seen people pull that shit with the pennies! They're crazy! Especially given the fact that if the house is old enough to have fuses it probably still has the original flammable cloth wiring. Reminds me of these guys that rip the ground prong off of their A.C. jacks.
Also kinda reminds me of a friend who lived in an old house with fuses & bad wiring. We were jamming there and our bassist had an original SVT. He ended up blowing 2 transformers and 2 sets of power tubes because 2 of the phases were swapped. After the 2nd time I figured something was wrong and tested the outlet and found it was wired wrong.
Yup it works. Nice bit of wrench'n there bro even though it is electronic, song did not put me to sleep anyway, the doors rattled a bit, lol. ATB
That doors cover was awesome!😀
I wish I could have you working on one of my amps so you might take a look at this other one.
It's a Yamaha "fifty" 112 and just goes fft....fft....FFFFFTTTTTT!!!!!
lol!
for now, it's a spare speaker.
ill get into it someday. It's pretty old, but it looks like a killer amp!
Great videos man!
nice bit of doors at the end.great song.ive a fender acoustic amp to fix this inspired me. it has noise but if i hit top of amp it stops..any suggestions welcome
Well, I'm sure you did your best... Just kidding, that was a great rendition of one of my favorite Doors songs. Peace
Great trouble-shooting vid and BONUS performance from the Guitologist!
Great video Brad
does JMF Amps mean anything to you if so you might be able find the service manual.
Great video , and very popular! Good educational video for technicians and guitarists.
Smashing that Doors tune man!!
Nice man! Great performance at the end!
You do yourself proud, 2 thumbs up!