19 Oct
2011
19 Oct
'11
7:05 p.m.
On 10/19/2011 2:21 PM, Tony Duell wrote:
Yeah, it's been awhile since I went over it (using the unofficial
schematic on HPCC) but I recall that the power looked fine but I was
getting no clock signal at all. The 65 powers up and a few segments on
the right hand side light up, but that's it. I seem to recall that the
custom chips on the display PCB generate the clock signals, but I don't
have any spares so I have no idea if replacing them would fix the problem...
- Josh
I also have an HP-65 which appears to be broken
beyond repair, alas...
You;'ll be able to get an unoffocial schematic from
HPCC, but unless it's
a PSU problem or you have a donor machine you are probably right about it
being beyond repair. The logic board contains 3 ROM chips and a 44-pin
metal can which cotnaisn 5 silicon dice (Control&Timing,
Arithmetic&Registers, 2 RAMs, card reader interface and clock buffer).
Enough signals are brought out to be able ot tell which has fialed in
most cases, but that's not a lot of use -)
-tony