20 Sep 2003, 13:02, JIM HOLSONBACK (1:123/140), wrote to MATT MC_CARTHY:

Hi JIM.

 JH> It gets to be kinda discouraging and time consuming to 
 JH> troubleshoot this type of board.  So many of them just seem to lay 
 JH> there dead, no matter what we try.  
...................

This 'ATX stuff' is sort of like working on modern TVs where the power
supply is derived from the flyback.  Naturally, if the set fails to power
up, there's no power supply to check first.  In the ATX case, the board has
to be able to turn on the power supply, which turns on the power to the
board to turn on the PS, etc., etc.  One big vicious circle!   :-((
...................

 MM>> The bulging caps are caused by age, drying out of the 
 MM>> electrolyte, and high temperature.  Lots of factors enter the 
 MM>> picture.  All electrolytics dry out with age, starting from the 
 MM>> assembly line and warehouse storage!

 JH> So, if I _ever do_ try to repair a mainboard with bulging caps, 
 JH> there is no need to go to the local "surplus electronics
parts" place, 
 JH> or to cannibalize off of a 3-5 year old 'dead' mainboard?

"Surplus electronics parts" are good for almost everything except
electrolytic caps, I would recommend avoiding that!  Cannibalizing is great
for trouble shooting, and I usually just tack the 'used' part to the bottom
of the board during testing (too much trouble to get the plated-thru holes
clean again just for testing).  Once I KNOW what's needed for the final
fix, then I get the right parts NEW, and solder them in properly.

 MM>> The 90 or so I've replaced thus far on the Soyo MBs have for the 

 JH> Were these "good quality,"  name-brand PS's?  BIR, I've read here
 JH> recently about el-cheapo power supplies killing mainboards, and 
 JH> now bad caps on mainboards killing power supplies.  Not a good 
 JH> situation, IMO.

Best I can answer is probably 'in-between'.  Definitely NOT your $300
"PC Power and Cooling" brand, but a grade up from the bottom of
the line that's normally offered with the cases.

 JH>  sometimes I almost the XT-AT days.  Troubleshooting seemed
 JH> simpler back then, but I wouldn't like to go back to those 
 JH> hardware performance levels, just the apparent reliability levels.

I really think "apparent" is the keyword.  There were so fewer of
them back then, and prices were high enough to support trouble shooting at
the board level.  It still was no fun pulling 36 individual RAM chips and
substituting them one-at-a-time before we got a RAM tester.  Nor was it fun
running all over a board with a logic probe to find a bad gate chip that
really only needed re-seating in its socket.   A customer who paid $3000 to
$5000 for an "AT" computer _expected_ that it could be fixed.

Now, computers are generally accepted to be disposable consumer items, and
few customers are willing to pay very much at all to fix a system that was
"almost obsolete" when he first got it home.   :-((


     Good luck...  M.

--- Msged/386 TE 06 (pre)