Dodgy stuff

[KingBollock]

I am going to ask advice on two unrelated things. I have been meaning to ask about the first one for years but I don’t like starting threads if I don’t have to, and I can foresee problems with the question. But I thought it’d give it a go any way.

 

I have a Peavey T-Max 500 rack amp. A few years ago it started playing up, it would start clipping, sounding almost like gurgling, or like it wasn’t getting enough signal, sometimes going quiet. Often I could fix this by turning everything up and whacking the strings. After we moved here about a year ago, it worked fine for a few weeks, but then the problem came back and no amount of whacking helped, including whacking the amp itself.
 

Then, a few days ago, I decided to have another look. I disconnected everything from it and was going to try running from the preamp out, to another amp. But the bloomin’ problem had gone again (like when your appointment for your GP finally rolls around…), though it returned the next day and has stayed.

 

When it’s playing up it makes no difference which channel (tube or SS) it’s in. Running a different preamp into the power amp section works fine (but I miss the amps own preamp). I have tried everything I can think of without opening it up. It’s definitely the preamp section, both channels. I have tried it with several different basses, both passive and active. I have also tried it with a patch cable in the effects loop, and the preamp out to the power amp in.
 

I’m thinking it’s probably going to be dodgy capacitors because the problem has become worse over the years. But does anyone have any other ideas? I am going to have a look inside at some point, but would like to have a clue what and where I should be looking at.

 

I am confident that I can open it up safely. I can’t afford to have a professional look at it. I know how to check for dry joints.
 

I know it’s a long shot but I thought it couldn’t hurt to ask.

 

======

 

The other thing is the centre detente in my bass’s pick-up blend pot. It is very difficult to feel. I did change the knob to one with numbers so that I could see its position, but they looked wrong. I don’t know how the detente works. Is it possible to modify it to make it more obvious? I have successfully opened and repaired pots in the past, but not one with a detente.

 

Thank you for looking.

[rushbo]

30 minutes ago, KingBollock said:

The other thing is the centre detente in my bass’s pick-up blend pot. It is very difficult to feel. I did change the knob to one with numbers so that I could see its position, but they looked wrong. I don’t know how the detente works. Is it possible to modify it to make it more obvious? I have successfully opened and repaired pots in the past, but not one with a detente.
 

 

I tend to replace blend pots on my basses with a three way switch, as I find this way easier than fiddling with a pot (even with a detente) for live work. I'm not too fussy about how nuanced i want my tone to be. You might lose a bit of flexibility, but with a switch, its way easier to change sounds quickly and you've got a strong, visual signal too.

[Downunderwonder]

Dodgy capacitors is a dodgy internet meme that will never die.

 

Since it's on both channels you can ignore the tube.

 

Probably nothing a capable tech can't track down for you.