[sebhc] H17-3 Power supply

Mark Garlanger garlanger at gmail.com
Sat Jul 29 17:56:00 CDT 2006

I took all three drives and was able to get a better view of the power supply.
I feel better now, it appears that some diode bridge was added and mounted
on the bottom of the case. I not sure if that was an upgrade for supporting all
three drives, or some type of user modification.


On 7/29/06, Barry Watzman <Watzman at neo.rr.com> wrote:
> 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.
> Thanks,
>   Mark
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