[sdiy] Debugging problem with 4-track

Gordonjcp gordonjcp at gjcp.net
Sat May 26 09:41:18 CEST 2018


On Fri, May 25, 2018 at 08:23:17PM -0230, Corey K wrote:
> 
> What might be happening here? I'd love to hear any hypotheses. Seems like a
> problem with the power distribution system, but what would be the first
> things to check? (I have a multimeter and scope). Is this a case that might
> require recapping? What would be the best way to investigate this? Any
> ideas would be much appreciated.

Nothing ever requires "re-capping", *ever*.  It's a good way to make
things worse.

It doesn't look like there are any service manuals readily available,
which is annoying.  At least the power input circuitry ought to be easy
enough to trace out.  If it works okay with a lower supply voltage that
makes me wonder if one of the voltage regulators has failed.  If it's
one of the three-terminal types, then if the ground pin has a dry joint
(they're linked to the heatsink tab and so get hottest) that would cause
it to stop regulating.

-- 
Gordonjcp



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