Repairing an old Pearl Distortion

[mboyd43]

Hey friends, buddy dropped off an old Pearl distortion that has super low volume in bypass and while engaged, but seems to work otherwise. Came very dirty, used some contact cleaner but no change. Will probably reflow a few joints, maybe replace the jacks as those solder joints look like they could be better. Other than that, does anyone know what might cause this? Thanks

 

[hamerfan]

After cleaning i would change the elkos first.

 

[GizzWizzKing]

Could be the angle but one of those caps that's laying down looks like it's bulging. +1 for inspecting the electros.

 

[swelchy]

deep cleaning with 99% iso and swap-p out all the electrolytics is where I'd start too... doesn't look like anyone's been in there mucking around with the wiring...

 

[mboyd43]

Good tips thanks guys, wouldn't have gone there first. Got a solder sucker coming in the mail.

 

[Stickman393]

Swapping electros isn't a bad idea on these old pedals. Little cleanup is a good idea too.

I'd be checking voltages. See if you can trace the power supply rails out.

Then...see if you can audio probe your way through it.

Those old boards tend to be relatively brittle: I've got an old Boss TW-1 that had a similar issue. Turned out one of the signal-path traces had broken, probably from a drop. Once I fixed the trace it was AOK.

 

[darwin999]

I'm unsure, but there *might* be something of use at these links

Pearl DS-06 Distortion

mirosol.kapsi.fi

Pearl DS-06 Distortion

Two layouts, one stock with a rotary switch and another layout by request which has a dual gang pot in place of the switch and the fixed r...

dirtboxlayouts.blogspot.com

 

[jwin615]

If it's low output in bypass too it's either coroded jacks or related to an always on(boss style) buffer. If it has a buffer, caps may be the fix. Given the footswitch style, my guess is there's a jfet buffer

 

[andrewsrea]

Inspect all the wires at the solder joints for breaks. The lead solder of the era had acid rosin in it to make it flow and would corrode (then break) its aluminum wires, simply by a function of time and oxidation.

Next, clean the switch with contact cleaner. It looks to be a mechanical switch with the signal running through contacts, versus a solid-state flip flop circuit. Heck, clean everything mechanical while you are at it!

Next I would test Q1, which is a FET buffer both sections have in common.