H744 +5 supply - easy to fix? - test-drb@ccmp.vtda.org

3 Mar 2004

On Mar 4,  8:22, Gooijen H wrote:

...
  I repaired 2 H744's up till now.
 They are indeed an easy piece to work on.
 One had a defective rectifier bridge (the 1 x 1 inch square
 block with 4 terminals) and the other was more peculiar:
 one big electrolitic capacitor (AFAICR it is connected
 directly to the PCB, fixed with screws) made a short circuit
 between the housing of the capacitor and a trace on the
 board. The plastic insulation of the capacitor some how was
 that bad to allow the short circuit ...! 
Hmmm... one of mine had a faulty rectifier too.  Not hard to diagnose
or replace, but I wonder if that's a common failure?  Another one had a
bad filter cap -- but it had died of age (leaked) rather than causing a
short.  Another common "problem" seems to be whistling from the coil,
if it's begun to delaminate.  Probably a sign of previously running
hot, and not necessarily anything to worry about.  Several of my
"brick" PSUs had faulty bulbs, and I found the easiest way to fix that
ws to replace the bulb with an LED and a resistor, as found on the
later versions.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York