On Jun 15, 2004, at 8:55 PM, Martin Sole wrote:
Some weeks a go I mentioned an Alpha 77 that a friend and I were going
to
check out. In examining it we paid attention to the comments made by
others
on here about what to look for, in particular the filter capacitor.
What we
found was a pool of oil under the amp and a greasy film on the diode
board.
It will all clean up but the cap is done for we think. Apparently Alpha
power want $800 but they have directed us to Dahl's who still want
$400.
What we are thinking is that maybe there are alternatives.
Will a suitably sized bank of electrolytics do the job?
The original capacitor probably started leaking oil after the solder
seal failed. This is much more likely when a capacitor that is
intended for intermittent flash service is used for continuous duty --
i. e., flash caps use thinner foil to reduce size, which increases
ESR, which increases I^2 x R loss, which makes more heat, which
stresses the seals more due to thermal expansion and contraction. ----
I would consider replacing the leaking oil cap with a bank of newer
design electrolytics. A cube of 2 by 2 by 2. 500wv electrolytics
should fit into the space occupied by the original cap. This would
provide a 4000wv rating. Digi-key <www.digikey.com> 2 sells
Mataushita/Panasonic 500wv electrolytic capacitors. / see P7456 on
p.785 of current catalog for a 30mm x 45mm, 220uF, 500wv unit.
However, this mod would require fabricating an assembly of the 8
capacitors. The good news is that the electrolytic cap bank will have
a higher ripple current capability than the original flash cap.
-- good luck, Martin. cheers
Can oil filled caps be re-conditioned?
Does anybody have something that will do for a 'sensible' price?
Any ideas?
73
Martin, HS0ZED
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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