zentner@aliphatic.ecn.purdue.edu (Michael Zentner) (12/10/90)
I've got a Compaq PC which I'm about 90% sure has a blown power supply.
My question is three fold:
1) Anyone know where I can get a compaq power supply for the Deskpro
for a reasonable price? Compaqs go for $270 or so, hah! For those
that don't know, I cannot just buy a cheap 150W power supply for an
XT because 1) the switch on the compaq comes out the back of the unit,
not the side, and 2) the compaq runs the power lines into the
motherboard, then from there to the accessories, as opposed to just having
several plugs emanating directly from the power supply. So, anyone know
of any power supply cloners making compaq clones?
2) If no power supply makers make reasonably priced supplies, anyone interested
in buying this machine? If so, I'll email you details about it's config.
I already have one working compaq and thus could not justify buying
a compaq supply to have two of the same box running. Had I only one
PC, that would be a different story.
3) OK, it's a three parter. This is the second time I've had the power supply
go out in this PC. Anyone know of similar problems? I suspect that it's
because Compaq runs their default monitors (monochrome EGA text, CGA
graphics resolutions) directly out of the box (as opposed to a separate
plug), which strikes me as a pretty silly design, but I'm sure there is
a reason they did it that way, justified or not.
Thanks for any help anyone can provide...
--
Mike Zentner
Purdue University, CMET Building zentner@cn.ecn.purdue.edu
West Lafayette, IN 47907 {ihnp4,ucbvax}!pur-ee!zentnercgordon@vpnet.chi.il.us (Crash Gordon) (12/15/90)
>Author: [Michael Zentner] >I've got a Compaq PC which I'm about 90% sure has a blown power supply. >3) OK, it's a three parter. This is the second time I've had the power >supply > go out in this PC. Anyone know of similar problems? A previous employer of mine used a _lot_ of Compaq portables. And they went through a __lot__ of power supplies! We bought a service contract from a third-party house, and the guy just had a van full of Compaq power supplies. ----------------------------------------------------- Gordon S. Hlavenka cgordon@vpnet.chi.il.us Disclaimer: Yeah, I said it. So what?
commgrp@silver.ucs.indiana.edu (BACS Data Communications Group) (12/21/90)
>Author: [Michael Zentner] >I've got a Compaq PC which I'm about 90% sure has a blown power supply. >3) OK, it's a three parter. This is the second time I've had the power >supply go out in this PC. Anyone know of similar problems? Compaq "lovable luggables" are very well-made _except_ for their power supplies. Power supplies are generally the least-reliable part of any electronic device; all the power passes through them, and they generate the most heat. Also, the power supply is usually an afterthought and its design is assigned to the most junior engineer. First rule of troubleshooting: Measure the power-supply voltages. A friend who designs switching power-supplies for Collins Radio says the Compaq's power supply is the WORST design he has ever seen! The most common problem in Compaq PC power supplies is cracked solder joints around a large power-transistor (in TO-3 package, mounted on heat sink): The transistor is bolted to the circuit board through threaded studs which are soldered to the printed circuit. The transistor gets quite hot in normal operation, and thermal cycling eventually cracks the solder joints. Since the transistor case is used as a circuit-board jumper (really lousy design!), the broken connection causes power-supply failure. The symptom is usually shutdown after a few minutes' warmup. Late models have power supplies with larger heat-sinks, which are somewhat more reliable. Repair: Re-solder the transistor mounting-studs (with a large soldering iron) and solder an insulated wire jumper between them. Removing the power supply is tricky-- You must unscrew a hex-head bolt near the bottom, which is hard to reach. DO NOT neglect to tighten the bolt upon reinstallation. -- Frank Reid reid@ucs.indiana.edu