26 Aug
2010
26 Aug
'10
12:27 p.m.
On Wednesday (08/25/2010 at 10:59PM +0100), Tony Duell wrote:
That much is certain :-). There is a hole and pad on the PCB for this pin.
I could trivially desolder the IC, straighten the pin, and solder it back
properly. But should I? What would others do?
_I_ would fix it. It's clearly not what HP intended, sadly it slipped through some quality inspection and certainly
isn't supposed to be
that way. I'd take the position of fixing it now, while the unit is
apart for other reasons, so that you don't have to take it apart again
later when it does fail and then risk damaging other aged things then.
The things most likely to be damaged if I have to keep on removing the
PCB are the Nylatch clips thst hold it in plave (those are those fixings
that look like an over-size LED clip with a central plunger where pushing
the plunger home spreds the 'clip', thus locking the thing into a hole in
the chassis). or the CRT. Now Nylatch clips I have 'in stock', but
finding a CRT coupdl be more of a problem. And I;d tather not have to
replace it for no good reason.
I had a similar decision which you folks offered input on-- which was
the apparently failed transformer in my SWTPC 6800 system (c. 1976).
I failed to close the loop on that story but in the end, I discovered
that the real problem was the lousy MOLEX connectors that were used
Seen that many times... Commodore PETs suffer from this, for example.
between the power supply PCB and the end of the power
harness going to
the motherboard. The pins in this connector were not mating well, were
corroded and had been heating up for some time (a long time ago!). The
white MOLEX shell was turning brown and was actually warm to the touch
when I would briefly power the machine on. I decided to replace this
connector with something similar but better and all the issues went away.
I think I've mentioend befroe that my PERQ 3A had disk problems when I
got it. It turned out that there's an in-line fuseholder in the 12V feed
ot the head disk (Maxtor XT1140 type of thing) and one of the terminal
screws in the holder was loose and there was thus a high-resistnace
connection there. It was a particularly nasty fault because the voltage
only driopped far enough to cause problems when the drive was seeking
(due to the extra current needed to drive the positioner coil). So it ws
not easy to spot....
-tony