[Premium-Rx] Premium-Rx Digest, Vol 137, Issue 9

[VK3XYZ]

Hi,
I note Nigel has posted the 300MB version. I've created a smaller (14MB)
version which is based on that 300MB version.

It can be found here:  

http://members.iimetro.com.au/~gcd/data.html

And yes, I agree with Nigel - good luck.

I've dealt with water ingress and associated corrosion a few times. If it
hasn't been exposed too long and it hasn't been too long since exposure then
I would suggest placing the receiver section that was exposed to water into
a isopropyl alcohol bath to displace the water (or remove the affected
boards if possible and treat those). I'd leave it in a sealed container in
the iso for at least a few days. Then let it dry naturally, or with warm
forced air.

If it has been exposed for some time, or it's been some time since exposure
then you can expect corrosion to most likely have set in and a full
disassembly of the boards and the chassis will likely be needed with each
inspected and treated as necessary. It can be very difficult to stop it once
It's set in. I've seen boards and mechanical parts sprout oxides for years
after being affected , with the affected metal being eaten away till there's
almost nothing left. 

Treatments that I've used to date on mechanical parts , depending on the
extent of corrosion include: liberal use of isopropyl alcohol; phosphoric
acid (not cola) to remove corrosion; subsequent treatment with an etching
primer and sacrificial coating (zinc) to stop the corrosion; and soda/sand
blasting to strip the surface corrosion  and any pitting. 

Boards are easier unless they have plated through holes, in which case they
need to be thoroughly inspected as they too can corrode over time and cause
huge problems. If boards have been exposed for some time then water likely
will have penetrated into semiconductors , creeping up the seals between the
plastic and the leads.  So even if they seem OK today you can typically
expect a reduced time to failure.

Given you indicate a coverage of an inch or two, then I'd suggest replacing
all of the regulators on the back panel. Moisture will have penetrated under
the metal/plastic seals of the TO-220s and the T03 may have ingress on the
glass seal too.

Cheers
Greg

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Message: 6
Date: Sat, 14 Apr 2018 10:03:25 -0400
From: Howard L Ritter Jr <hlritter at twc.com>
To: Premium-Rx at mailman.qth.net, boatanchors at mailman.qth.net
Subject: [Premium-Rx] Harris RF-550 schematic
Message-ID: <FE43AB2E-4255-473D-BCB1-E926CE24322A at twc.com>
Content-Type: text/plain;	charset=utf-8

My Harris 550 was standing on its back panel on the floor when the basement
flooded to a depth of an inch or two, and now it blows the power fuse as
soon as it?s turned on. (It?s long since dried out.) I have it in the hands
of a capable technician, but he tells me he can?t find a schematic for it.
Can anyone help with a link or a file?


Thanks!
?howard n7exn

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End of Premium-Rx Digest, Vol 137, Issue 9
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