After watching your video, I managed to repair a TEK485 that I had in the workshop for a long time. This instrument also had a short circuit in the Tantalum capacitors. Once replaced, the instrument was reborn to new life. Thanks from Italy. I learned a lot. Stefano Bargiacchi. Retired electronics engineer.
Thanks Ananda! Tek made troubleshooting power issues a breeze with this one. Being able to isolate sections by pulling those comb jumpers was an ingenious design.
@@raygianelli3612 Without a doubt. They were first the ones to bring them out of the "approximate" era into some kind of precision, and just kept getting better while the other makes dreamed of catching up!
@@ydonl Very true. I read a great book, "Bill and Dave: How Hewlett and Packard Created the World's Greatest Company". They admitted they could never catch up to Tek for oscilloscopes.
They really did. I imagine today it's just board replacement, but back then you had to take the time to troubleshoot and repair. In this case, they really were the good old days!
Back in the day when that scope was made electrolytic caps were much larger in size for the same value and leakier. Nowadays you can get elec caps much smaller, but still not as small as tant caps. They are also less leaky. Tek tried to keep the size of the 465 475 and 485 scopes to a small portable size, not like the 545, etc older models. Tant caps were the way to go. Worked in electronic repair for over 50 years. Tektronix back then always made repair of their equip easy to troubleshoot. Today it can be hard just to get a schematic and a lot is Windows/computer based.
Yeah, today's components are way better than what was available back then. Hopefully they'll continue to make through hole components for a few more years. I've owned a 547A, 547B and a 7603. Currently my daily driver is a 2445A. A have a DSO, and while the measurement capabilities are amazing, the display on the old CRO's is more to my liking. And the DSO just plain sucks for X/Y.
Thank you for an awesome video. I have never thought of tracing a power supply the way you did in this one. So safe and affective. Also the info on the caps is very useful. I learned a lot today.
Thanks Wayne! Take care of myself so health is good so far. Remember this old joke? "I've read so much about the bad effects of smoking, drinking and drugs that I've decided to give up reading". 😁
Good troubleshooting process. I always suspect tantalum caps first when troubleshooting any Tek or HP gear from this era. I usually do a visual inspection of all tantalums before even applying power. Sometimes a shorted tantalum will appear brown or even charred. I replace these first and sometimes that’s all it takes. And, as you say, next on the list is cleaning dirty pots and switches with DeOxit.
Lot to be said for a good visual examination! There have been instances where I pulled out the schematic and went through the paces only to find something that was visibly bad. So yeah, definitely a good practice!
Thank you for another excellent video. great troubleshooting techniques! I was not aware Tektronix used combs before. I have a 465 which was working one day and then blows the primary line fuse the next day. I traced it to a fault somewhere on the 55 volt rail, then put it aside for another day. I'll have to check the diagrams and find the combs to pull. Alcohol and freeze spray didn't work for me finding the suspected shorted tantalum cap. This winter I hope to pull the combs and ohm out that 55 volt rail.
The 465 doesn't use those combs, which makes troubleshooting just SO much more fun! That 55 volt supply is used as a reference for many other voltages in the power supply, so it goes to a lot of different places.
@@raygianelli3612 Good grief! Thanks for the prompt reply. Well that means the 465 goes to the very bottom of the "to do" pile. The 475 will be next. Story time: There was a guy selling 3 Tektronix scopes for $5 each at a ham radio flea market. Somebody bought the newer one, I bought the 454 & 475. The seller told us, one scope worked. When I got home I found out it was the 454! Nice scope.
Great teaching on how to follow a short. It takes time to do a job like this properly, but most people give up too quickly. Mainly I think because they don’t have sufficient knowledge to work on the piece.
Agreed. I had a few amazing mentors along the way that helped me to understand how these things worked, and what to do when they don't. I don't have much patience for most things, but for whatever reason I do for electronic troubleshooting. I can (and do ) stare at schematics for hours, until they give up their secrets. My only superpower is that I refuse to give up!
@@raygianelli3612 Dog gone right never, never, never give up. If we got paid according to the real hours we worked this stuff we would all be richer. But I just enjoy doing it, it gives you such a good feeling.
@@cwradio4571 Good feeling is right! It's like doing a puzzle. I find troubleshooting to be fascinating. It's especially interesting when someone has been in there before you.
I have a 2246 doing the same thing. Clicks and the fan jumps when trying to power up. Where do i find the schematics so i can try to troubleshoot mine?
Between 1967 and 1974 i was not using high tech equipment like this. In doing TV less expensive test equipment was my forte.in 1974 I started at RCA labs where more sophisticated test equipment was the order of the day.
I have a tektronix 455 that just stopped working I'm pretty well versed in hi voltage but I'm still weary about working with it in unfamiliar circumstances. Amplifiers no problem. I have never repaired a scope though
It may not be a high voltage issue. Tek scopes often use one of the voltages in the low voltage power supply as a reference for other voltages. So if that voltage is off it will affect others.
I enjoyed this video a lot. Learned serveral things. I'm fixing a Panasonic VP-5564A oscilloscope and it have this following problem. It powers on but shows no trace. I probed the power supply at all the test point I can see +12,-12,+5, all correct. When I measured the voltage across the deflection plates of the CRT between pin 3 and 4, the screen flashes a slim vertical rectangular box for a split second. When i touch these two pins repeatedly, the box moves at a rate set by the time/div. Touching other pins doesn't seem to have any effect on the screen. So the horizontal controls work but for some reason the trace doesn't show up. Do you have any idea? Also I can't find any schematic for it on the internet.
@@raygianelli3612 it didn't back then. But today, I probed the CRT pins but I clipped the MM's COM to the chassis. The pin number goes 4-3-2-1-14 clockwise. It shows -166v on pin 4. I believe pin 3 is the cathode with - several kV so I didn't probe it. When I probe pin 2, a spark appeared between the pin and my probe. Then somehow the screen comes to life and shows a fairly bright horizontal line. Something kept the trace invisible must have discharged. I tried to lower the inten so it doesn't burn in the phosphor but inten knob doesn't work. What work is all the horizontal controls like position, time/div the trace does repond like it should. It was set to GND coupling and no signal was inputed. When I input a signal, it still show a straight horizontal line so matter how I set the settings. Focus knob barely changes the trace. In short, horizontal works for sure, vertical, focus, intensity broke.
New to your channel, i adore the quality of these scopes. I have a 454a without beam at all; a ht issue i think. Without primary acting dangerous what tests can i make.? Thanks for this video!
Well, I don't know if you saw the second video, but my HT issue was caused by a failed rectifier in the LV supply. Ensure that you have all the low voltages first. Appreciate the thanks!
My understanding is that you can replace them with a low leakage electrolytic. The only place I'd be leery of using electrolytics is in switch mode power supplies. If there's a tantalum in a SMPS I'd replace like for like.
@@raygianelli3612 The low value ones 4.7uF and lower can be substituted with a polyester cap like the Wima MKS02. on the 2465 Tek scope power supply there some small value tantalum ones, that I would change just to be on the safe side.
@@Djinnsos This morning another one went on the +15VDC supply. This one let the smoke out, so I had to open the garage to vent out the toxic smoke. Films are a good choice up to 4.7µF, as you mention. They get too bulky and expensive after that.
@@raygianelli3612 The old tantalums are almost like playing a game of whack a mole. Almost worthwhile to replace them all. Unfortunately, it would be a big job as many as Tektronix used in these older 'scopes.
@@capriracer351 Oof. Yeah, I did consider replacing them all. Weird how it was only the +15VDC supply where they failed. Another one went this morning. It was easy to find, since it burned up. Had to open the garage to let those toxic fumes out! 😳
Excellent. You looked for the short with your multimeter set to Ohms... I understand that method. However, you had power still applied to the DUT, throughout this process. I am wondering what the advantage to the power-on method might be? How does the benefit weigh out against the risk? Please and thank you. I am not finding fault, here, I am truly asking a genuine question, without any sideways critical intent. Subscribed. Cheers!
Thank you for couching your inquiry in such diplomatic terms! To be clear, the resistance testing was done with no power applied. Even a small amount of voltage will invalidate your results. I did watch the video to see why you would have thought it was done with power on, but I thought it was clear it was not. Apologies for any misconception.
@@raygianelli3612 Thank you for your reply. My guess it that I over-thought it. IIRC, you were calling out voltages, while probing. Oh, I think I get it... You were probing the power rails - looking for the short on them, - but no power was being applied. Well, there you go... And, you just taught me something else... I had not ever considered that any type of power would invalidate a resistance reading. However, that makes perfect sense, as (IIUC) the meter is reading the drop in voltage of a known voltage reference to calculate the resistance. I look forward to more of your videos. Thank you so much for teaching us!
Not exactly. The only time I had one on my bench was for a quick test for a friend that was buying it. I do distinctly recall being quite impressed with the sound, even through my small bench speakers.
I love the fact this was designed for service. You don't see that much anymore.
Nice troubleshooting Ray. Thanks for sharing your journey!
OK, wow, this just made my day!
Thank you, Paul! You're who I want to be when I grow up. 😁
After watching your video, I managed to repair a TEK485 that I had in the workshop for a long time. This instrument also had a short circuit in the Tantalum capacitors.
Once replaced, the instrument was reborn to new life.
Thanks from Italy.
I learned a lot.
Stefano Bargiacchi.
Retired electronics engineer.
Thanks Stefano. Messages like this just make my day!
Ray,
That was "fast and furious." Great technique. Thanks.
Thanks Ananda! Tek made troubleshooting power issues a breeze with this one. Being able to isolate sections by pulling those comb jumpers was an ingenious design.
@@raygianelli3612 You are correct. It is a long while since I opened a 465 and 465M. I don't believe that feature was in them. Kind regards.
I absolutely LOVE my 485. Excellent oscilloscope. Nice work!
Hands down the best analog scopes were Tektronix, IMHO.
@@raygianelli3612 Without a doubt. They were first the ones to bring them out of the "approximate" era into some kind of precision, and just kept getting better while the other makes dreamed of catching up!
@@ydonl Very true. I read a great book, "Bill and Dave: How Hewlett and Packard Created the World's Greatest Company". They admitted they could never catch up to Tek for oscilloscopes.
Hi Ray, very logical and methodical breakdown of circuit tracing. Have to say that Tektronix make it easier to fault find!
They really did. I imagine today it's just board replacement, but back then you had to take the time to troubleshoot and repair. In this case, they really were the good old days!
Back in the day when that scope was made electrolytic caps were much larger in size for the same value and leakier. Nowadays you can get elec caps much smaller, but still not as small as tant caps. They are also less leaky. Tek tried to keep the size of the 465 475 and 485 scopes to a small portable size, not like the 545, etc older models. Tant caps were the way to go. Worked in electronic repair for over 50 years. Tektronix back then always made repair of their equip easy to troubleshoot. Today it can be hard just to get a schematic and a lot is Windows/computer based.
Yeah, today's components are way better than what was available back then. Hopefully they'll continue to make through hole components for a few more years.
I've owned a 547A, 547B and a 7603. Currently my daily driver is a 2445A. A have a DSO, and while the measurement capabilities are amazing, the display on the old CRO's is more to my liking. And the DSO just plain sucks for X/Y.
@@raygianelli3612 Yes, display not so great but great for the GPIB output uses.
Thank you for an awesome video. I have never thought of tracing a power supply the way you did in this one. So safe and affective. Also the info on the caps is very useful. I learned a lot today.
Hi Ray, new to your channel .Looks good so far so I hit the magic button.stay healthy
Thanks Wayne! Take care of myself so health is good so far.
Remember this old joke? "I've read so much about the bad effects of smoking, drinking and drugs that I've decided to give up reading". 😁
Good troubleshooting process. I always suspect tantalum caps first when troubleshooting any Tek or HP gear from this era. I usually do a visual inspection of all tantalums before even applying power. Sometimes a shorted tantalum will appear brown or even charred. I replace these first and sometimes that’s all it takes. And, as you say, next on the list is cleaning dirty pots and switches with DeOxit.
Lot to be said for a good visual examination! There have been instances where I pulled out the schematic and went through the paces only to find something that was visibly bad. So yeah, definitely a good practice!
Thank you for another excellent video. great troubleshooting techniques! I was not aware Tektronix used combs before. I have a 465 which was working one day and then blows the primary line fuse the next day. I traced it to a fault somewhere on the 55 volt rail, then put it aside for another day. I'll have to check the diagrams and find the combs to pull. Alcohol and freeze spray didn't work for me finding the suspected shorted tantalum cap. This winter I hope to pull the combs and ohm out that 55 volt rail.
The 465 doesn't use those combs, which makes troubleshooting just SO much more fun!
That 55 volt supply is used as a reference for many other voltages in the power supply, so it goes to a lot of different places.
@@raygianelli3612 Good grief! Thanks for the prompt reply. Well that means the 465 goes to the very bottom of the "to do" pile. The 475 will be next. Story time: There was a guy selling 3 Tektronix scopes for $5 each at a ham radio flea market. Somebody bought the newer one, I bought the 454 & 475. The seller told us, one scope worked. When I got home I found out it was the 454! Nice scope.
Great step-by-step locating the fault!
Thanks Don! Fortunately the designers had servicing in mind. That's not always the case.
Great teaching on how to follow a short. It takes time to do a job like this properly, but most people give up too quickly. Mainly I think because they don’t have sufficient knowledge to work on the piece.
Agreed. I had a few amazing mentors along the way that helped me to understand how these things worked, and what to do when they don't.
I don't have much patience for most things, but for whatever reason I do for electronic troubleshooting. I can (and do ) stare at schematics for hours, until they give up their secrets. My only superpower is that I refuse to give up!
@@raygianelli3612 Dog gone right never, never, never give up. If we got paid according to the real hours we worked this stuff we would all be richer. But I just enjoy doing it, it gives you such a good feeling.
@@cwradio4571 Good feeling is right! It's like doing a puzzle. I find troubleshooting to be fascinating. It's especially interesting when someone has been in there before you.
Tek scopes are a thing of beauty
No argument here!
U got a 466 and I love it too. Mind is equipped with the DMM option installed and the temperature probe.
I have a 2246 doing the same thing. Clicks and the fan jumps when trying to power up. Where do i find the schematics so i can try to troubleshoot mine?
Between 1967 and 1974 i was not using high tech equipment like this. In doing TV less expensive test equipment was my forte.in 1974 I started at RCA labs where more sophisticated test equipment was the order of the day.
I really liked the fault finding procedure😊
Thank you. Sharing this kind of knowledge/experience is the whole purpose of this channel.
Thanks this might get me started on the one I picked up at the thrift store a few months ago
Instructive video as usual !
Thanks Roro. That's what I aim for, so it's nice to know that it was instructive!
Wow how smart is that. Great job man
4:30 If you unplug the unit but leave it powered, would it discharge faster?
Part of it would. It has an inverter, which then feeds the rest of the power supply. So the inverter is the only part that would be affected.
I have a tektronix 455 that just stopped working I'm pretty well versed in hi voltage but I'm still weary about working with it in unfamiliar circumstances. Amplifiers no problem. I have never repaired a scope though
It may not be a high voltage issue. Tek scopes often use one of the voltages in the low voltage power supply as a reference for other voltages. So if that voltage is off it will affect others.
You’re an inspiration. Thanks for sharing
Wow, thank you so much!
I enjoyed this video a lot. Learned serveral things. I'm fixing a Panasonic VP-5564A oscilloscope and it have this following problem. It powers on but shows no trace. I probed the power supply at all the test point I can see +12,-12,+5, all correct. When I measured the voltage across the deflection plates of the CRT between pin 3 and 4, the screen flashes a slim vertical rectangular box for a split second. When i touch these two pins repeatedly, the box moves at a rate set by the time/div. Touching other pins doesn't seem to have any effect on the screen. So the horizontal controls work but for some reason the trace doesn't show up. Do you have any idea? Also I can't find any schematic for it on the internet.
Does it show a trace when you input a signal?
@@raygianelli3612 it didn't back then. But today, I probed the CRT pins but I clipped the MM's COM to the chassis. The pin number goes 4-3-2-1-14 clockwise. It shows -166v on pin 4. I believe pin 3 is the cathode with - several kV so I didn't probe it. When I probe pin 2, a spark appeared between the pin and my probe. Then somehow the screen comes to life and shows a fairly bright horizontal line. Something kept the trace invisible must have discharged. I tried to lower the inten so it doesn't burn in the phosphor but inten knob doesn't work. What work is all the horizontal controls like position, time/div the trace does repond like it should. It was set to GND coupling and no signal was inputed. When I input a signal, it still show a straight horizontal line so matter how I set the settings. Focus knob barely changes the trace. In short, horizontal works for sure, vertical, focus, intensity broke.
I've learned that if you want to have a Tektronix Scope with no problems in a long time, replace ALL tantalum cap's, especially in the power lines.
New to your channel, i adore the quality of these scopes. I have a 454a without beam at all; a ht issue i think. Without primary acting dangerous what tests can i make.? Thanks for this video!
Well, I don't know if you saw the second video, but my HT issue was caused by a failed rectifier in the LV supply. Ensure that you have all the low voltages first.
Appreciate the thanks!
Tek used tantalum caps for a reason. Right? What's the impact of replacing them with a plain electrolytic?
My understanding is that you can replace them with a low leakage electrolytic. The only place I'd be leery of using electrolytics is in switch mode power supplies. If there's a tantalum in a SMPS I'd replace like for like.
@@raygianelli3612 The low value ones 4.7uF and lower can be substituted with a polyester cap like the Wima MKS02. on the 2465 Tek scope power supply there some small value tantalum ones, that I would change just to be on the safe side.
@@Djinnsos This morning another one went on the +15VDC supply. This one let the smoke out, so I had to open the garage to vent out the toxic smoke.
Films are a good choice up to 4.7µF, as you mention. They get too bulky and expensive after that.
@@raygianelli3612 The old tantalums are almost like playing a game of whack a mole. Almost worthwhile to replace them all. Unfortunately, it would be a big job as many as Tektronix used in these older 'scopes.
@@capriracer351 Oof. Yeah, I did consider replacing them all. Weird how it was only the +15VDC supply where they failed. Another one went this morning. It was easy to find, since it burned up. Had to open the garage to let those toxic fumes out! 😳
Excellent. You looked for the short with your multimeter set to Ohms... I understand that method. However, you had power still applied to the DUT, throughout this process. I am wondering what the advantage to the power-on method might be? How does the benefit weigh out against the risk? Please and thank you. I am not finding fault, here, I am truly asking a genuine question, without any sideways critical intent. Subscribed. Cheers!
Thank you for couching your inquiry in such diplomatic terms! To be clear, the resistance testing was done with no power applied. Even a small amount of voltage will invalidate your results. I did watch the video to see why you would have thought it was done with power on, but I thought it was clear it was not. Apologies for any misconception.
@@raygianelli3612 Thank you for your reply. My guess it that I over-thought it. IIRC, you were calling out voltages, while probing. Oh, I think I get it... You were probing the power rails - looking for the short on them, - but no power was being applied. Well, there you go... And, you just taught me something else... I had not ever considered that any type of power would invalidate a resistance reading. However, that makes perfect sense, as (IIUC) the meter is reading the drop in voltage of a known voltage reference to calculate the resistance. I look forward to more of your videos. Thank you so much for teaching us!
Thanks, the video helped me
Glad to hear it!
Good stuff Ray, you ever worked on a Pioneer Spec 2?
Not exactly. The only time I had one on my bench was for a quick test for a friend that was buying it. I do distinctly recall being quite impressed with the sound, even through my small bench speakers.
Don't handle the CRO so rough!!