Afraid to open my amp but don't want to pay a repairman.
- Thread starter solspirit
- Start date
With a SS amp, I wouldn't be as worried, especially if the amp has been sitting for a bit. The dangerous bits are pretty self-explanatory, they are the larger capacitors that you see. Provided YOU don't touch anything with both hands that are in the circuit, it is actually really hard to get shocked. If you really want to discharge the amp, it's pretty easy. Either using a cable or a pair of scissors, just make a contact between both sides of the capacitor, if they are vertically ( radially ) mounted, you will need to find a trace that leads from the + side of the capacitor and connect that to ground. Just repeat that a few times for each capacitor. Most amps have a safety bleed resistor though. It is just a resistor in the power supply section that allows the voltage to bleed to ground.
That being said, I highly doubt that you would be able to find the problem, let alone fix it if you are already that fearful and uneducated about amplifier repair. Generally, if something works partially, it means that the parts in the circuit have not failed completely, which means that it won't be obvious what is actually wrong.
Storytime: I had a Peavey Ultra 120 that was not switching channels properly. I did what I could and traced it down to the relay switch. Replaced the switch and it worked, sorta, when it wanted to. Then by total accident, I moved the midi connector ( for channel switching ) and saw that one of the leads was broken. As soon as I bridged that break in the connector the amp switched like a dream. The point is that even a somewhat experienced amp repairman ( at the time ), I couldn't 100% assess what the exact problem was. It was by a stroke of luck that the actual problem was exposed.
If you are no comfortable or confident about playing inside the amp, you probably shouldn't be. That saying " whether you think you can, or you think you can't, you're right " is very true here. If you already have doubts, there is a reason. It is not likely that you will hurt yourself, but you can. And the fact that you can, is reason enough to leave well enough alone. If you seemed a little more confident or had more electrical knowledge I would say go for it, but in this case, I would say the $85 bench charge and perhaps $5 in parts and two hours in labor to fix it is probably a safe bet. If it costs you more than $250 to fix it, I would be surprised, it may be less? If that is not worth it to you, or you can't swing that kind of cash, then I don't know what to say?
That being said, I highly doubt that you would be able to find the problem, let alone fix it if you are already that fearful and uneducated about amplifier repair. Generally, if something works partially, it means that the parts in the circuit have not failed completely, which means that it won't be obvious what is actually wrong.
Storytime: I had a Peavey Ultra 120 that was not switching channels properly. I did what I could and traced it down to the relay switch. Replaced the switch and it worked, sorta, when it wanted to. Then by total accident, I moved the midi connector ( for channel switching ) and saw that one of the leads was broken. As soon as I bridged that break in the connector the amp switched like a dream. The point is that even a somewhat experienced amp repairman ( at the time ), I couldn't 100% assess what the exact problem was. It was by a stroke of luck that the actual problem was exposed.
If you are no comfortable or confident about playing inside the amp, you probably shouldn't be. That saying " whether you think you can, or you think you can't, you're right " is very true here. If you already have doubts, there is a reason. It is not likely that you will hurt yourself, but you can. And the fact that you can, is reason enough to leave well enough alone. If you seemed a little more confident or had more electrical knowledge I would say go for it, but in this case, I would say the $85 bench charge and perhaps $5 in parts and two hours in labor to fix it is probably a safe bet. If it costs you more than $250 to fix it, I would be surprised, it may be less? If that is not worth it to you, or you can't swing that kind of cash, then I don't know what to say?
solspirit
Ultimate Post Liker
I definitely not going to open it now, I love to tinker and learn new things but this just isn't the thing to do it on.
It does go away when I turn it down to zero, so maybe I'll just get a reverb pedal for now.
solspirit
Ultimate Post Liker
Ii guess I'll at least and probably the most, open it and look.
Artie
Peaveyologist
What I do is simply connect my DMM across any large caps. (A day after the amp has been unplugged.) The meter itself will discharge the cap, and you can actually see if there's any residual charge on it. Once it gets down to a volt or two, you're fine. Clip-on leads are your friend here.
solspirit
Ultimate Post Liker
Haha I told my gf 2 nights ago that I needed to order some clip on leads, I just haven't gotten around to it yet.
Artie
Peaveyologist
Pomona is my favorite. A little pricey, but will last a lifetime with reasonable care.
https://www.pomonaelectronics.com/products/dmm-test-leads-and-probes/test-companions
https://www.pomonaelectronics.com/products/dmm-test-leads-and-probes/test-companions
devastone
Well-known member
Ewizard is right, SS amps are pretty safe, it's tube amps with the big filter caps that get charged to high voltage that are the problem. And yeah, they can tickle, Mike Soldano burned a hole in his thumb from one of those, I just got a nice jolt once. So, I try to remember to discharge them now, usually just put a screwdriver across the terminals, makes nice sparks if they are well charged.
SS usually run at much lower voltages, but yes the filter caps can build up a charge but usually discharge pretty fast, you can always unplug it and turn it on for a little while, that should discharge them. And know, the chassis won't hurt you, it's grounded. If half the things brought up in this thread were true we'd have musicians dying on stages daily, well, back when there were musicians on stages.
But, as said, if you are that scared to look in it, doubt you are going to do any worthwhile trouble shooting, take it to a tech. A hum is usually a sign of a filter cap going bad anyway, and we have already established a fear of those.
Also, if you do go poking around inside, make sure it is unplugged first.
SS usually run at much lower voltages, but yes the filter caps can build up a charge but usually discharge pretty fast, you can always unplug it and turn it on for a little while, that should discharge them. And know, the chassis won't hurt you, it's grounded. If half the things brought up in this thread were true we'd have musicians dying on stages daily, well, back when there were musicians on stages.
But, as said, if you are that scared to look in it, doubt you are going to do any worthwhile trouble shooting, take it to a tech. A hum is usually a sign of a filter cap going bad anyway, and we have already established a fear of those.
Also, if you do go poking around inside, make sure it is unplugged first.
Last edited:
alex1fly
Well-known member
+1000
Not a DIY project. You probably get that impression from everyone else too. Even if you're careful, you can accidentally touch something without meaning to. Happened to me once working on a flashing sign. F****** terrifying. It was an unholy sensation. My entire body head to toe felt like it was going through a cheese grater.
NegativeEase
New member
Especially in amps where the reverb is in the bottom of the unit (Like Fender Deluxe/Twins etc) -Those tiny copper or copper cladded with alloy leads to the spring coils inside the tank corrode and get noisier and noisier as the conductor oxidizes.
Pulling a reverb tank out and opening is a pretty safe excursion into an amp -they are usually away from Caps and you can unplug the RCAs and with 3-4 screws pull it right out.
solspirit
Ultimate Post Liker
It seems to be in the bottom corner
NegativeEase
New member
Yeah, totally safe to check out if it's away from the folded chassis holding the amp
Have you swapped the 12Ax7 tube feeding the Reverb circuit? that's probably the first thing to do -easy, cheap, and safe to do...
What's the amp model?
solspirit
Ultimate Post Liker
It's ss
NegativeEase
New member
Oh, I must have misread -I thought it was an old tube hofner.
solspirit
Ultimate Post Liker
It's right around the time that Schaller was dabbling in them, they were the same amps made in the same factories.
But my model seems to be lost somewhere because it's a different configuration than all the others I can't find anywhere. It seems that Schaller stuck with the tubes and Hofner kept making them for a few more years.
I did a cap job on an old Peavey head. I called them and asked them which were the filter caps on the schematic. They sold me the parts and told me which ones they were. It worked out great.
Before beginning the job, I got a large resistor and dissipated whatever charge the caps were holding. If memory serves, you just hold the resistor across the terminals of the capacitor. Of course it needs to be a beefy resistor so it doesnt go up in smoke.
Before beginning the job, I got a large resistor and dissipated whatever charge the caps were holding. If memory serves, you just hold the resistor across the terminals of the capacitor. Of course it needs to be a beefy resistor so it doesnt go up in smoke.
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