[sdiy] Korg SDD-3000 5 volt supply problems

Adam Inglis 21pointy at tpg.com.au
Sun Nov 18 06:07:38 CET 2018


Thanks all

> On 18 Nov 2018, at 1:45 AM, Adam Inglis <21pointy at tpg.com.au> wrote:
> 
> I haven’t re-flowed the entire board though.

Er.. that’s exactly what I should have done first.

Turns out that if you flip the board over and inspect it while you plug in the connector from the transformer secondaries, only then does the crack in that particular winding’s pin joint become evident (under a lot of reading glasses balanced on your nose!!). This is well away from the heat affected areas, and originally I didn’t inspect these areas while pushing on a connector on the opposite side of the board.
Doing this with the connectors for the analogue and digital boards… well, whaddya know… the 5 volt pin solder joint to the digital board has a crack in it too. I wonder if this is why the problem seemed to move around!

One other observation: this is a deep rack unit with physically large circuit boards. To work on the PSU and the analogue board, you remove the top panel. To work on the digital board, you have to flip the whole thing over and remove the bottom panel. I thought I was kidding myself, but while I was working on the digital board, the glitches seemed much less frequent. In this orientation, those connector plugs would have been pulling down on the pins, closing the cracks in the joints!

Anyway, I feel a bit silly having gone through all this rigmarole when it was such a simple fix after all, but I really do appreciate everyone’s input

cheers
Adam




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