I knew Ike would have the definitive answer for the correct fuse value!
Indeed, the rectifier diodes lead a rough life as they deal with large
power-on inrush surges due to charging of the large filter caps in the
PSU.
I'm sure Ike does this same thing: up-size the rectifier to the highest
amperage rating that will physically fit into the available space inside
the unit. It also doesn't hurt to up-size the PIV (voltage) rating as well.
If the rectifier is a 4-terminal "bridge" that is bolted to the chassis,
like this:
http://www.mouser.com/Search/Refine.aspx?Keyword=625-GBPC3506-E4
....be sure to apply a thin film of silicon heat sink grease on the
underside of the bridge to help move heat from the bridge to the metal
panel when the bridge is bolted down.
The example bridge I linked above is rated at 35 Amps. I believe I've
seen rectifiers in that same package rated at 40 Amps or more.
Best,
Bri
On 4/19/2011 21:03, Ike wrote:
Hi all,
The correct mains fuse value for a stock PS-3 is 5 amp slow-blow, as
Brian says. I THINK that the Sytek rebuilt units have up rated
transformers which could account for the 7 amp fuse on your spare
supply. If the fuse has vaporized, the most likely culprit is a failed
bridge rectifier. Any competent tech should be able to replace it.
Best
Ike
Ike Zimbel
Zimbel Audio Ltd
416-720-0887
www.zimbelaudio.com <http://www.zimbelaudio.com>
Sent from my iPhone
On 2011-04-19, at 9:44 PM, Tommy Mokas <[email protected]
<mailto:[email protected]>> wrote:
Thanks for the response Brian. Well, the fuse is definitely blown,
which is disheartening at this hour...but alas, I'm going to go get
more fuses right now, and I'll report back soon. Hopefully its
something simple, although I'm doubting it is for some reason. Anybody
have a neotek tech in NYC, in case I need to make that call?
On Tue, Apr 19, 2011 at 9:05 PM, Brian Roth
<<mailto:[email protected]>[email protected]
<mailto:[email protected]>> wrote:
If the inside of the glass tube of the fuse has black "crap" blown
all over, that sounds as if there is a short circuit somewhere
inside the power supply. But, if the wire link inside is merely
broken, it could be a case of "who knows?"
I don't have schemos for that unit, so I can't say whether 5 or 7
Amps is correct. It almost certainly needs to be a slow-blow type.
I think you will be OK trying a 5A slow-blow in there to see if it
blows again. If it blows again, STOP and have the PSU serviced. If
the fuse holds and the desk works, the next step would be to see
if 7A is actually the correct value, which could explain the blown 5A.
Best,
Bri
On 4/19/2011 19:09, Tommy Mokas wrote:
Hello Neoteks,
Quick question, if the fuse on the back of the power supply blows,
what should be my main concerns? There was no other reason for
me to
believe that the power supply wasn't functioning correctly
until my
biz partner went to turn it on and it didn't power up. I just
got back
into town to find a blown fuse in the back.
The fuse that was in it was a 5A 250V 3/3. However I have a backup
power supply (which I've never needed) that has a sticker
indicating a
7a fuse. I assume this referring to amps, but I want to be
sure. Is it
possible that the other power supply (which apparently serviced in
'96) has a changed value on this particular fuse? Is that a
mod done
to these?
And for my final question, am I risking the power supply by
putting
the same fuse in only to have it blow again? I don't want to
do any
more damage but I do have work to do :). Any insight is really
appreciated, especially if you're a night owl such as myself.
Thanks
so much!
Best,
Tommy Mokas
Casa Nova Studios
<http://www.twitter.com/tommymokas>www.twitter.com/tommymokas
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