DEC troubleshooting

From: Allison J Parent <allisonp_at_world.std.com>
Date: Thu Nov 5 17:32:09 1998

< Sure. Tell the customer he/she will be down an extra hour while
< you extend the board to find the fault, desolder the chip
< and replace the 10 cent bus driver. Nope. Swapping was reality in the
< when I was there. Board level (early 80's DEC) was (unfortunately)
< replaced with shotgunning and option swap out by many in the late 80's.

Economics... less down time and the failed card could be returned for
repair and retest. Cards repaired under controlled conditions had better
reliability.

Option swap really used to fry me.

< Sure. Had one of those guys at Naval Air Propultion in Trenton, NJ.
< Customer: "The te16 won't go on line. U134 should go low, but it's floa
< Can you bring us a driver chip."
<
< Field Service: "We don't have it in stock, but I'll get one in the next
< three weeks if I P1 it... Or I could come down and change the LAW boar
< on the drive (LAW -- TE16 Logic and Write board) in about 15 minutes."

Reality was that it cost as much to handle the chip as the whole board!

< Absolutely. That's a very common failure along with the diode and cap
< on the VT100 video cards that's underrated.

Severely underrated. A 50V cap running at 70! The diode was a victim.
A remember a box of returned cards the size of a large chest refrigerator
at WJO01 in '84. I happen to look at it and after the third or forth card
surmized the failure... annoyed a few people that I could see that without
a full field study. Oh, the cause was a transmission error, the person
that drew up the BOM copied the wrong values. It would go years that way
before someone becuse of the problem would pull the original DD, CS, KPL
and see they didn't match. Classic case of why CADD was a desireable
thing.

Allison
Received on Thu Nov 05 1998 - 17:32:09 GMT