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SE/30 Damaged Pad at C3.. part at Y1?

Tarantulas

Well-known member
I carefully removed all the caps on my SE/30 motherboard this morning, and had good luck all the way up to C3.... which I either accidentally lifted, or was eroded away by a leaky cap.

Does anyone know an alternative location for the second pad that I can jumper to?  Or should I try connecting to the via?

Also, there appears to have at one time been a part at Y1... what do I need to replace that with?

Thanks again!

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View attachment 20848

 

IlikeTech

Well-known member
Flip it over and see if you can find where the via goes.  It looks eaten away.  Use a multimeter to check yourself.

 

CharlesT

Well-known member
All those caps are just bulk bypass caps for the various power supply voltages. The plus side goes to the voltage rail, the non plus side of all of them goes to the ground plane. The only exception would be for a negative supply, in which case it's just the reverse, but I don't have the schematic handy to be positive about C3. But that's easy to check with a DMM, if the C3 + node connects to the other negative nodes then it's a negative voltage. In any case, if you can glue the new cap to the PCB (soldering the + terminal, of course), then you can just run a wire to one of the other adjacent grounds (again assuming it's not a negative voltage).

If anyone has an SE/30 schematic handy it would be great to confirm the polarity of the C3 node.

 

Tarantulas

Well-known member
I have continuity at the via on the front and the reverse of the board, so I think I'd be clear to just put a small jumper over to the via.

I found the oscillator that previously lived at Y1 rolling around in the cast, so that's been reinstalled.  To verify, two leave oscillators don't have polarity, right? I believe I have it reinstalled in it's original orientation (one leg was sheered off at the board, so it was slightly longer than the other that looks like it was desoldered at one point.  Very strange.

 

Tarantulas

Well-known member
Sorry about the spelling / grammer errors above...

"I found the oscillator that previously lived at Y1 rolling around in the CASE, so that's been reinstalled.  To verify, two LEAD oscillators don't have polarity, CORRECT? I believe I have it reinstalled in ITS original orientation (one leg was SHEARED off at the board, so it was slightly longer than the other - WHICH looks like it was desoldered at one point.  Very strange."

 
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