Peavey Triple X leaking electrolyte

[Mick Bailey]

I have two Peavey Triple X 2x12 combos in right now, both with the same fault. At first glance it appeared that electrolyte was leaking from one of the main filter caps.

In particular, each amp has serious corrosion to the two low-voltage dropper resistors nearby. In one amp the legs are eaten right through and the ceramic bodies appear to be oozing a foamy liquid. The other amp (pictured) has split the ceramic resistor body and the other resistor is open-circuit. Interestingly, the top of the split resistor is wet with a gel. Given that this is the top-side of the component when installed in the amp it's difficult to see how this would occur.

Anyhow, this get more perplexing, as on close inspection the removed caps show no signs of leakage and are just damp around the outer edge where capilliary action has drawn the liquid around them. The seals and teminals are dry.

Both amps are brand new and were bought directly from Peavey as not working when they closed UK operations.

The amps are suffering from a variety of faults - shorted rectifier diodes, burnt and corroded tracks, burnt resistors, open resistors, no continuty between through-hole vias, incorrect mains voltage selector position, shorted transistors, shorted op-amps, and corroded socket pins.

The main puzzle is the corrosive gel; it looks like capacitor ooze, but I'm not entirely convinced. Has anyone else seen this? Apologies for the focussing, too late by the time I came to post this....

[xtian]

That's really weird! What orientation does this board normally sit when amp is in operation, components up or down? Anyway, modern electrolyte is a paste, not a liquid, and won't flow very far. I think that's another contaminant we're seeing.

[Mick Bailey]

Components face up.

The amps have also been stored in damp conditions. I suppose if the electrolyte was hygroscopic it could have liquified, but it wouldn't explain how it would collect on top of a resistor.

I've just tried sitting the caps pins-up in a pan of boiling water to see if they would ooze, but after 15 minutes nothing. They're getting replaced anyhow. My though is also that maybe the liquid is from somewhere else.

But where?

[52 Bill]

Are you sure that it isn't slopped on contact cement? Sometimes they will use that to glue down larger components like filter caps. The line workers applying the stuff are not judged on neatness.

[Mick Bailey]

It's certainly something corrosive and water-based and not cement or adhesive. I was aware of a burning sensation when I was working on the amp and it's where I got some of the stuff on the back of my finger. In places it's eaten right through the tracks - nothing left.

The lower resistor in the picture has it's top blown right off and the spiral WW element exposed (and corroded). The stuff is lying on top of that.

[Leo_Gnardo]

It's certainly something corrosive and water-based and not cement or adhesive. I was aware of a burning sensation when I was working on the amp and it's where I got some of the stuff on the back of my finger. In places it's eaten right through the tracks - nothing left.

It's sodium hydroxide, AKA lye or Dran-o. Yes, best to avoid skin contact or breathing the dust. Sure does like to corrode metal. And you.

[g1]

The amps are suffering from a variety of faults - shorted rectifier diodes, burnt and corroded tracks, burnt resistors, open resistors, no continuty between through-hole vias, incorrect mains voltage selector position, shorted transistors, shorted op-amps, and corroded socket pins.

All those faults for 2 amps?
That sounds really strange. Maybe they were some kind of training stations or experiments or something?

[Enzo]

Or something got splashed on them. If the caps are not leaking, then it is not likely electrolyte

[Jazz P Bass]

I had a chat with Grant at Peavey the other day & we got to talking about assembly goofs & he mentioned something about at one time the Chinese assemblers used the wrong capacitor hold down goo & it became conductive.

No mfg dates or amp models were given though.

[The Dude]

Grant Brown is a wonderful human! He's assisted me many times. Always informative, helpful, and friendly.

[gbono]

Who made the filter caps? I'm guessing Peavey received some counterfeit parts

[Enzo]

Because someone used the wrong hold down goo?

[Mick Bailey]

Theyre made by IC.

When I look at the damage it's concentrated around the resistors. If the caps were leaking I would expect to see more damage underneath the caps and signs of leakage around the terminals or seals. Both amps have identical problems.

I've peeled the cap shrink-wrap and they're bright and untarnished right around the rolled lip. Cap value checks out, no short and very low ESR.

The stuff is conductive - there's a trace that references the heater voltage to +24v and this runs right next to one of the cap + lines. It's shorted right across and put 1/2 B+ (around 240v) onto both the heaters and LT supplies to the op-amp and transistors.

The amps are made in the US, but if it's anything like the UK you can buy in imported stuff and call it 'Made In'. The definition here is 'The country in which the last major finishing operation was completed'

So, a Chinese cabinet, Chinese speaker, Chinese PCBs and Chinese chassis can be called Made in the UK if it's all put together here.

[g1]

he mentioned something about at one time the Chinese assemblers used the wrong capacitor hold down goo & it became conductive.

Same thing happened to Yamaha SPX90's once they were fairly aged.

When I look at the damage it's concentrated around the resistors.

Maybe the sealant that's used in those ceramic type power resistors?

[Enzo]

I am still inclined to believe someone dripped some of his Mountain Dew on the thing during break.