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Continuing saga of the Power Supply   Message List  
Reply | Forward Message #1181 of 1261 |
Re: [sony-mxp-3k] Continuing saga of the Power Supply

Matt,
   First fire the Tech who charged you for 3 Darlington's to fix the +24V supply.  There is only ONE Darlington on the +24V.  What serial number and date of manufacture?  The early Power Supplies, the good ones, had the heat sink Isolated from Chassis ground.  If your Three Darlington Tech forgot to do this then it blows up again.
   Will the power supply work without the console?  If you have no volts at the filter cap, yeah dead bridge.  AC input DC output unless the crowbar kicks and blows the fuse.  A new bridge rectifier is cheap.
  University, Hmmm probably some good students that know how to read a voltmeter and schematics.  Get the power supply working stand alone before powering the console.  The +24 V is very similar to the + 18V.
 
My three cents.
 
Later
----- Original Message -----
From: meyah
Sent: Friday, July 10, 2009 2:54 AM
Subject: [sony-mxp-3k] Continuing saga of the Power Supply


Hi --

We have a 3036 in our university which is loved (and feared) by our
students. Our problems started two years ago when we relocated it from
one room to another, and the 24v leg of the power supply failed shortly
thereafter. We had it repaired -- 3 Darlingtons and a capacitor, to the
tune of $300 -- but it failed again within a week.

Then last year when the 18v leg started failing, I got some great help
from this forum. I think I chased down some possible shorts, and the 18v
leg is good again. But I wasn't able to figure out the 24v problem. Now
that it's summertime and the students are gone, I'm ready to take it on
again.

The technician who fixed it the first time seems knowledgable, but is
suggesting putting in a 24v switching power supply on just the 24v leg.
Does that make sense? It seems wrong to me.

It's been a long time since I went through the 24v supply, but it seemed
to me that I got 24v from the transformer, but not from the next link in
the chain (the huge capacitor?). The tech mentioned something about a
diode bridge, and of course the Darlingtons. (Yes, we now have 2" of
clearance on all sides, but that hasn't helped the 24v supply.)

Any suggestions of a plan of attack?

Matt


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Forward 		Message #1181 of 1261 |
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Hi -- We have a 3036 in our university which is loved (and feared) by our students. Our problems started two years ago when we relocated it from one room to... 		meyah
Offline Send Email 		Jul 10, 2009
6:55 am

Matt, First fire the Tech who charged you for 3 Darlington's to fix the +24V supply. There is only ONE Darlington on the +24V. What serial number and date of...
Tom Graefe
consoledewd
Offline Send Email 		Jul 10, 2009
11:54 pm
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