30 May
2007
30 May
'07
4:14 p.m.
It was thus said that the Great Tony Duell once stated:
I'm not sure aobut the '2 hours' (but then again I didn't put a time
limit on replacing the capacitor either), but I reckon I could implement
a TIL if I had to.
But I also thing that's a raiter unfair comparison. Replacing a capacitor
which has obviously failed doesn't involve much thoguh. Implementing a
TIL odes.
I think a fairer comparison to implementing a TIL would be to 'Find the
logic fault in this machine, you have no schemaitcs, and none were ever
available0. I've done that several times, i generally do end up tracing
out the schematics for interest, but I have been known to fix the fault
first.
An example of wehat I mean. I bought an HP9816 which had gave an error on
start-up. It was something about a memory failure, and gave an address,
and 'W:xxxx' R:'yyyy'
A web search got me a service manual (boardswapper guide :-)) for a
related machine, the 9826, and it appeared the memory fault was in the
text video RAM. And assuming W: and R: were value written and value read
respectively, the problem was bit 11 (I think).
So I started from the DIO expansion slot (which I had a pinout for) and
traced data bit 11 across the monitor PCB to the connector where the text
video PCB plugged in. I then traced it on the text video PCB trhough a
buffer chip to a data pin on a 6116-like RAM. Desoldered that chip and
fitted a replacement from my junck boc. Had the machine perfect [1]
within an hour of getting it.
[1] Well,m apart for ma low-emission CRT.
-tony
As regards having spare time, it's amazing how complicated some of my
repairs can be...But replacing a capcitor isn't one of them
Maybe for you it's easy. Possibly not for me. And possibly for the
person requesting a new Apple /// power supply (I've lost track of who that
was). To put it into perspective you might understand, can you implement a
Forth (or Forth-like) system in two hours? I did that the other night
because I was rather bored and it was more interesting than I what I was
supposed to be doing [1]. If you can't, why not? It's not that
complicated.