82e13 VCA card -18v connections

[MartyAckerman]

Hello,
I've got a channel that does not pass audio and illuminates the cut light when I bring the large fader up. I isolated the problem to the 82e13 VCA card and then further to the -18v power rail. I noticed that T3 was not getting -18v and that it's pin 4 was connected to pin 11 of T2. I found no conductivity to the card's pin 29, where -18v arrives on scene.

I also found that the 611 motherboard had a blown 2A fuse at pins 48-50, where that -18v enters the channel strip.

When swapping to a known good VCA card, I found that someone had added a wire to connect pin 4 of T1 to pin 11 of T2, effectively shunting that -18v to the node that I was expecting to find it in the broken card. Clearly, that's not how it was originally - it must have worked without that wire patch at some point, right?

I've added a couple pictures of the bad card alongside the good one. You can see the red wire I'm referring to. The top is the bad card in both images.
https://imgur.com/a/7c4ldMQ

Does anyone have any insight as to what happened here? Maybe it was after ea certain revision, or a common workaround for a known problem? Should I just add in that patch wire? I'm wary of doing so without knowing why it was added to begin with.

Thanks for any help!

[horizonsound]

Hey there,

It's pretty common to get corroded traces on the E13 board. I note that the board with the jumper wire still has it's original capacitors. Those orange ones leak and create lots of problems.
I've also experienced the most damage on boards that were of the era of having a gold can dbx vca.

Recap and clean corrosion, check power rail traces and repair.

Anthony.