Compaq Systempro processor board repair

Tothwolf tothwolf at
Sat Jan 3 03:05:11 CST 2015

I have a Compaq Systempro 486DX2/66 processor board (Spare No. 133825-001) 
which I'm trying to repair that is missing some SMD components on the 
solder side of the board. Does anyone happen to have one of these in their 
collection and would be willing to read the component markings so I can 
repair this one? Thankfully Compaq used SMD capacitors with readable codes 
on them which indicate their values.

My board is missing R135, C227, C178, and C153.

Looking at the solder side of the board with the card edge connectors 
facing towards you, R135 and C227 are towards the top left corner, about 
1" from the top and 1.5" from the left. They are opposite U54 which is on 
the component side of the board. I /think/ R135 is supposed to be 56 ohms 
and C227 0.047uF (based on some similar looking circuitry on the board) 
but I have no way to verify if those are the correct values.

C178 is about 1/4" from the top edge of the board and just to the left of 
U511 (ATT7C174J). It is opposite U43/U60 which is on the component side of 
the board.

C153 is just above the longest card edge connector, about 1" from the 
leftmost contacts. It is opposite U32 which is on the component side of 
the board.

I salvaged this board out of a scrap bin many years ago and have already 
made lots of repairs to it, but I've never quite finished it. I'm about to 
order some other SMD parts for other projects, so if I can figure out what 
value these parts are supposed to be, I can pick up a few extra reels of 
components and finally finish this board.

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