Should you correct production mistakes?
ard at p850ug1.demon.co.uk
Wed Aug 25 16:59:31 CDT 2010
When you are cleaning up and restoring a piece of classic computer
hardware, would you correct any minor mistakes made in the original
I have a particular exmaple in mind. In bits on myu bench at the moment
is an HP2623 graphics terminal This was HP's response to the well-knwon
Tektronix terminals, it is, however a raster scanned device. But it has a
little state machine (or parhapes you could call it a very simple
procesosr) to speed up line drawing.
On the video monitor PCB (HP call it the 'Sweep' PCB), there is a 74LS221
dual monostable chip in the common HP horixontal drive circuit, The first
half of the chip delays the sync pulse (and the delay time is controlled
by the horizontal centering control), the second half is triggered from
that and provides a pulse of known width to the horizontal drive transistor.
But I digress. You don't need to know any of that...
WHile cleaning the dirt off this PCB (HV attracts dust electrostatcally,
of couse), I noticed that the ground pin of this IC never made it through
the board. It's folded under the package, but has been effectively
surface-mount soldered to the pad when the board was wave-soldered. It
works, but I can't beeleive it's as good as a proper through-hole
connection, and it's certian;y not what was intended.
I could trivially desolder the IC, straighten the pin, and solder it back
properly. But should I? What would others do?
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