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Tiago79's picture
Last seen: 5 months 2 weeks ago
Joined: Jun 18 2023 - 12:21pm
Need advice on SS Amp stored for long time

I'm the lucky guy (or not) who found and bought a brand new Audio Research DS-450 solid state amplifier in the sealed box! This amp has been in storage for at least 12 years, maybe longer! I have paid US$ 4.000 for it with no warranty from the seller.

I haven't turned on the amp yet!

When I opened the box and took off the top cover I found some signs of mold as you can see in these pictures:

But what is making me worried are 4 capacitors. I don't know if it's mold or if it's a possible leak.

See the pictures:

There are no signs of leaks at the bottom near the PCB, only at the top of them.

What do you think of these capacitors? Mold or Leaking?

I'm thinking of using a Variac transformer to slowly increase the voltage to try and slowly reform these capacitors and see what happens. This amplifier uses a linear power supply, but I don't know if its protection circuits will allow that.

What should I do? I would really appreciate if you guys could guide me.

Thanks a lot!

SAS Audio
SAS Audio's picture
Last seen: 1 month 2 days ago
Joined: Jun 6 2007 - 6:56am
sas audio

A question to ask. Any ideas of the storage temperature range during these 12 years?

If within acceptable temperature limits, I would reduce the primary AC voltage to just a small fraction of the AC voltage
and power on, maybe a fifth of the normal AC line voltage.

Leave the component on for an hour or so, and then up the
voltage to a quarter of the voltage for an hour. Gradually increase the voltage for several hours until full voltage is achieved. A finger on the capacitor to check for warmth during this process. If by some outside chance there is warmth on the capacitor, then substantially reduce the voltage and continue to let the capacitor "form".

I have capacitors sitting for more than 15 years that measure quite good. There is no leakage on top of the capacitors nor
at or around the terminals.

Extreme storage temperatures is your main enemy.

Hope this helps.


hollowman's picture
Last seen: 8 hours 49 min ago
Joined: May 28 2009 - 12:59pm
Reply issue

I’ve been here, as a member, even before the 2009 forum update (that's the join date on the profile which got reset somehow in 2009).
Anyway ...

I would reply with an on-topic remark, but for some weird reason, many of my posts and threads have been disappearing from this forum.
I’ve emailed Jim Austin about the issue several times but we’re getting nowhere.
As some of you may recall, I posted a lengthy thread right here in Amplification “Power in Overpower “ a few days ago.
It’s gone. I do have existential proof — the page was in my iPhone cache and I saved it as a PDF.
Jim A has a copy, too. I’ll post a link to it soon.
But until Stereophile can get to the bottom of the magic act issue, I’m holding off on participating.

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