Cleaning and Restoring a Badly Corroded PSU

[dwight]

I would remove the transformers before putting it in the wash.

The big one doesn't look to be hermetically sealed.

Dwight


________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Phil Blundell via cctalk <cctalk at classiccmp.org>
Sent: Monday, October 23, 2017 3:27:29 PM
To: rob at jarratt.me.uk; Rob Jarratt; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Cleaning and Restoring a Badly Corroded PSU

On Mon, 2017-10-23 at 21:45 +0100, Rob Jarratt via cctalk wrote:
> I am now looking at the H7826 PSU that came with a TURBOchannel
> Extender. It
> looks like there may have been capacitor leakage and some heatsinks
> will
> need to be replaced. I have posted pictures here:
>
>
>
> https://robs-old-computers.com/2017/10/23/corroded-h7826-power-supply
> /

Maybe the photos don't do justice to the full horror but it doesn't
look all that bad from what you've posted.

The heatsinks do look a bit corroded but, if they are aluminium (which
I would guess they are from the photos) then this might just be
dampness rather than anything more sinister.  Aluminium does tend to
rot a bit in prolonged contact with water, and if it is also in contact
with steel then you get an electrolytic reaction which can be fairly
ruinous.

I doubt the heatsinks are a standard part you can buy off the shelf.
They have a bit of a custom look about them.  But, unless you are
worried about authenticity of those parts, a standard heatsink from
Farnell etc will work just fine.  If you do want the authentic article
then you might need to get some replacements machined.

As for cleaning the board, given that it seems to be relatively low-
tech I would probably be fairly comfortable putting it in the
dishwasher on a shortish cycle.  Then give it a bit of a rinse with
deionised water and let it dry out.

The caps don't look obviously leaky, and (unlike batteries) it doesn't
seem to be common for capacitors to ooze their electrolyte without
fairly evident physical distress.  But replacing them is probably a
good plan anyway!

p.