Afraid to open my amp but don't want to pay a repairman.

[solspirit]

My reverb is humming bad, it's like a white noise hum. I've read that SS amps hold good a charge after they're unplugged and it could be dangerous if you don't know what you're doing, which I don't. Anything you guys can tell me about either?

 

[Gtrjunior]

If you have a reverb tank there are usually 2 RCA jacks plugged into it. Check that they are inserted properly.

 

[ehdwuld]

Hum along with it

 

[solspirit]

If you have a reverb tank there are usually 2 RCA jacks plugged into it. Check that they are inserted properly.

I know nothing about this, it's an early 70's SS Hofner/Schaller KV 40.
. I heard it was deadly to touch the chassis when you open it, what's up with that?

 

[formula73]

Dude you’re going to kill yourself if those filter caps discharge through one hand and ground through the other. It’ll stop your mfn heart.

I’m not fucking around.

 

[solspirit]

Dude you’re going to kill yourself if those filter caps discharge through one hand and ground through the other. It’ll stop your mfn heart.

I’m not ****ing around.

I guess this is what I heard.
​​​​​​ How do repairmen avoid this?

 

[Gtrjunior]

Put one hand in your pocket and don’t take it out when tinkering in the amp.

Like Formula said, it’s the filter cap that hold the charge...don’t touch them!

 

[formula73]

Ground probes and dead checks with a multimeter. There are yt videos but I’m absolutely telling you to take it to a tech unless you like the idea of being dead.

 

[JamesPaul]

I'm not advocating that you open it up.

This topic in The Vault has some basics and explains the dangers.

https://forum.seymourduncan.com/foru...ou-safety-tips

 

[JamesPaul]

If you can find the RCA jacks on the Reverb Tank that Gtrjunior noted, you can power down the amp, unplug the cables, spray some electronics cleaner (I use Deoxit) on the plugs, the plug and unplug a few times to clean any oxidation/corrosion which may have built up.

​​I'm not overly optimistic this will resolve a hum, but it won't hurt anything.

 

[solspirit]

Ground probes and dead checks with a multimeter. There are yt videos but I’m absolutely telling you to take it to a tech unless you like the idea of being dead.

I think I'm going to bring it in.

 

[JamesPaul]

You haven't moved the amp, or brought any new electronic devices into the area, since the hum started have you? Just wanted to rule out environment.

 

[solspirit]

You haven't moved the amp, or brought any new electronic devices into the area, since the hum started have you? Just wanted to rule out environment.

Not at all, it's been in the very same spot since I brought it home 2 years ago. The noise started about 3 months ago then gradually got worse.

 

[Aceman]

How did the noise get worse if you aren't playing? How did you even know? Nevermind, not important...

Guys who work on such things discharge the caps. I don't know the procedure and I don't want to because electricity can be dangerous. Every amp builder I have spoke with says don't try this at home if an amateur.

 

[jeremy]

sounds like something is failing but since its not a catastrophic failure, you probably wont see anything. if you arent confident, just bring it to a tech

 

[JMP/HBE]

Went thru this phase in the 1960's but gotta start somewhere.

 

[JamesPaul]

I think I'm going to bring it in.

Likely a good idea. Tracking down hum and noise typically requires an oscilloscope anyway.

 

[Demanic]

+1 to everyone that says take it to a tech. I've opened amps but only to see if I could see something burnt. Haven't gone rooting around in there though. I'll do low voltage electronics and save high voltage for someone with the right training and equipment.

 

[formula73]

Hw did the noise get worse if you aren't playing? How did you even know? Nevermind, not important...

Guys who work on such things discharge the caps. I don't know the proce4dure and I don't want to because electricity can be dangerous. every amp builder I have spoke with says don't try this at home if an amateur.

It’s not hard but you HAVE to know what you’re doing and even then, a healthy bit of respect keeps you on your toes.

 

[Demanic]

Well, there are safe ways to discharge a cap. But you have to know what you are doing. High voltage isn't very forgiving of mistakes.