Should you correct production mistakes?

Tony Duell 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 
production?

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.

But wanyway...

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?

-tony




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