[sebhc] H17-3 Power supply

Barry Watzman Watzman at neo.rr.com
Sat Jul 29 16:39:04 CDT 2006

With no diode bridge (or with wires for 2 of the diodes), you would be
putting AC instead of DC into the unit.  This could be catastrophic, it
could destroy not only the power supply, but the drives.

Almost any power diode will work.  You need a maxiumum of a couple of amps
per drive, so say 6 amps max (but probably not really that much), the
voltages are all low (50 volt diodes would be fine).

If the diodes are used in a full wave bridge, then the single square part
would also work.

-----Original Message-----
From: sebhc-bounces at sebhc.org [mailto:sebhc-bounces at sebhc.org] On Behalf Of
Mark Garlanger
Sent: Saturday, July 29, 2006 4:16 PM
To: sebhc
Subject: [sebhc] H17-3 Power supply

I just received an H17-3 drive case and drives. I was told that
"The H17-3 triple drive blew a fuse when I turned it on"

I tested the fuse, and unless he replaced it, the fuse is fine.
What's preventing me from testing/turning on the case, is that
there is NO diode bridge on the power supply board. There is
the spot to put 4 diodes, but two of them are empty and the
other two (very top and bottom) just have a wire there. I betting
that it's putting an huge extra burden on the voltage regulators.

The board is slightly older board than I have in my other two
drive cases, (85-2107-2 vs. 85-2107-3), but I can't imagine that
a diode bridge would isn't be needed. According to my Z37
manual, those should be 3A, 100V diodes. The closest thing
I found out the local Fry's are 5A, 100V - I'm assuming that the
higher amps just mean they can handle more and can be
used in place of the 3A ones. Let me know if that is the wrong
assumption. Also, Fry's had a square little 'diode bridge', internally
it's all 4 diodes properly connected. It's rated 8A, 100V - I don't
remember enough of my EE to be sure if that would be proper
to replace it. Looking at the circuit, I'm thinking that the current is
only going through one diode at at time, therefore a diode
bridge that was rated at 3A, 100V would be an equivalent
replacement, so this 8A one should also be fine. Let me know if
I'm mistaken here too.

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