Peavey Mace / Deuce / Classic?

robgilmo

https://imgur.com/a/A26YpI9

ICBM

It's where the arrow points.

robgilmo

Any tips on how to get in there? Im thinking maybe bypassing this with a fly lead across the contact points?

ICBM

robgilmo said:

Any tips on how to get in there? Im thinking maybe bypassing this with a fly lead across the contact points?

I do it by pushing the tip contact down and poking a small strip of sandpaper into the gap, then release it to trap the sandpaper and pull the sandpaper back out.

Bypassing it will work fine if you don't intend to use the loop.

robgilmo

I'll try the sand paper first, if that doesnt work then its probably not the contact at all but I'll try a bypass too. I put it back together and tried it and it seemed to work better, the volume had a mind of its own though then after about 30 seconds it went back to how it was. I think we might be barking up an empty tree here and the problem may well be something else, but I'm one of those people who always suspect the worst anyway.
I see the bottom input has the same kind of jack, I'll give that a clean too while I'm in there.
Its lovely outside, beer drinking in the garden weather! Sods law.

robgilmo

The sandpaper didn't work, I buttoned it all up and there was nothing from it at all! So my guess is ive made the contacts lose contact altogether. So Ive connected the two wires (black and green) together and bypassed the contact altogether. Im still not convinced. I did notice these burnt caps though.  These are on what I think is the power supply?


https://i.imgur.com/VpR9O96.jpg

https://i.imgur.com/oUTeB3r.jpg

https://i.imgur.com/genMJpj.jpg

https://i.imgur.com/trCfmNa.jpg


And this is on the other board.

https://i.imgur.com/HiqI2ek.jpg

Im thinking that might be the problem, 

ICBM

That’s just where the wire is welded on.

Check that the large blue resistor in the top left corner of your third pic isn’t loose.

Is it working with the jack switch bypassed?

robgilmo

Its much better, but its still not right, its still randomly fluctuating in volume, my guess is it hasn't been used in a fair few years, it doesn't add up though, why would the seller replace two tubes in an amp that he said he hasn't used in years? I reckon he switched it on , it didn't work, he replaced two tubes, the red light came on and that's as far as his testing it went. there is no way this amp was working any time lately.
Anyhow, that's enough of me moaning, clean the speaker terminals next, something somewhere along the signal path is showing resistance and letting go. I will check the resistor, to be fair a dry solder joint does sound likely, 

ICBM

robgilmo said:

Its much better, but its still not right, its still randomly fluctuating in volume, my guess is it hasn't been used in a fair few years, it doesn't add up though, why would the seller replace two tubes in an amp that he said he hasn't used in years? I reckon he switched it on , it didn't work, he replaced two tubes, the red light came on and that's as far as his testing it went. there is no way this amp was working any time lately.
Anyhow, that's enough of me moaning, clean the speaker terminals next, something somewhere along the signal path is showing resistance and letting go. I will check the resistor, to be fair a dry solder joint does sound likely, 

Cut the push connectors off the speaker wires and solder the wires to the speakers - clean the terminals first, and wrap the wire through the hole before soldering. I know some people will say this isn't necessary! But I have come across a lot of problems with contact in these over the years - often where the wire is crimped into the push-connector rather than between the connector and the speaker, so don't just solder the connectors on. Yes, you can buy new push-connectors and a tool to fit them, but why bother when soldering is just better anyway...

There are quite a few other possibilities for what might be causing it too, but it will probably just be a process of elimination.

If the seller replaced two valves they may have been visibly dead - if it's been stored in a garage or somewhere and got very cold, they can crack and it's very obvious that they are, the silver 'getter' goes white. In theory this shouldn't happen at UK winter temperatures, but it does. Garage storage would also be likely to produce corrosion elsewhere too.

robgilmo

I have soldered all the speaker wires and I think we may have nailed it, it had a bit of an epi when I switched the phaser on, nope, I tell a lie, its just done it again! Does the signal pass through the pedal? I noticed when it was cutting in and out the reverb would go first leaving a clean signal behind it, the pedal cable has been replaced and the din on the amp looked well suspect. 

ICBM

robgilmo said:

Does the signal pass through the pedal?

No, but a short in the cable - a badly-soldered DIN plug most likely - could do all sorts of things...

If the reverb kept on going after the main sound cut out, you can definitely be sure the fault is not in the power amp or speakers.

robgilmo

Ive disconnected the pedal, its back to how it was the first time round, no output except when the gain is on full and it makes a very distorted sound when the guitar is strummed. It was going Ok for a while there after I soldered the speakers. I have noticed the lights for the selected channels go out when the pedal is unplugged, is this normal?.

ICBM

robgilmo said:

Ive disconnected the pedal, its back to how it was the first time round, no output except when the gain is on full and it makes a very distorted sound when the guitar is strummed. It was going Ok for a while there after I soldered the speakers. I have noticed the lights for the selected channels go out when the pedal is unplugged, is this normal?.

I can't remember - I think so.

Sounds like there is something up with the switching circuit.

Check that all the ICs in sockets are properly seated - give each one a firm press.

robgilmo

The plot thickens, I switched it off for a good 5 or 10 minutes, switched it on and its working properly,  lasts a few minutes then cuts out for a second then back, it will run for 20 seconds then do it again, the frequency of these spells of cutting out gets higher until it just goes altogether into its distorted randomness.
I'm guessing this is a thermal issue? A dry joint isn't convincing me because if I smack the amp it doesn't change anything!

ICBM

robgilmo said:

The plot thickens, I switched it off for a good 5 or 10 minutes, switched it on and its working properly,  lasts a few minutes then cuts out for a second then back, it will run for 20 seconds then do it again, the frequency of these spells of cutting out gets higher until it just goes altogether into its distorted randomness.
I'm guessing this is a thermal issue?

Yes. At a guess that sounds like it might be something like a voltage regulator with thermal protection shutting itself down. The cause of that is likely to be a shorted IC which is drawing too much current. Or it could be a leaking electrolytic cap causing charge to build up on the wrong side of it - not one of those big ones, it will be a small cap in the signal path. Difficult to be any more specific (even if that's accurate) from this point on - there's a lot to check. The good news is that if you need to get it looked at you have a good idea of the symptoms and probably where to look, so a good tech shouldn't have too much trouble.

robgilmo

I don't think I will be going that far with it, they really don't sell for much these days on EBay, 100 - 150 quid looking at past sales and I phoned the guy I bought it off and he is willing to take it back , it will have cost me 50 - 60 quid in diesel and another very long drive to the other side of the world  , if I pay a tech the best part of 50 quid an hour plus parts I'm looking at another £100 quid?  I dunno, seems like a load of hassle to me either way.

ICBM

You're probably right in financial terms. I just think it's worth fixing because they are fantastic-sounding, very under-rated and - once overhauled - usually very reliable amps, and should be worth far more than they actually sell for. But if you have a relatively easy way out that would avoid opening a potential can of worms - if it's been badly stored that might apply - then it may be worth waiting for a better one to come along.

robgilmo

That's the maddest thing, after speaking to the guy and discussing the amp and how we were going to proceed (a fairly painful conversation) I switched it on and decided to see if it would go pear shaped again before clearing everything up. That was what, 25 minutes ago? Its still working. I haven't been playing for 25 minutes, around 10 or so , but its still working when I pick the guitar up.
It was very hot in here today, that wouldn't make a difference would it?

robgilmo

And now its gone again, It seems that between switching it off and on its lasting longer each time before going bad again, Apparently it sat for 10 years unused, could the caps have dried out or lost their charge and are now reforming? The guy said when he brought it out of storage and tried it it needed two tubes, it had no output at all.

ICBM

I suppose it's possible! Although I doubt it, caps don't usually repair themselves like that.

My guess is that unless the valves were visibly faulty, the two things are completely unrelated. Even if both of the faulty valves were on the same side of the amp, it would produce a fairly strong output, but oddly distorted at higher volume. If it was one on each side the amp work work fine but just have a little less maximum output volume. Unlike many later Peaveys, the valve filaments aren't in series on these, I'm almost certain.

Just turning on an amp which has sat unused for ten years isn't the best idea really...