I've got a non-working HP98035 real time clock module (for HP9825, etc) 
on the bench.
 
It accepts commands, it sends something back, so I think the bus 
interface and microcontroller are all fine. The problems are : 
 
The real time reads back as 88:88:88:88:88
 
There is no activity on the crystal connected to the AC5954N clock chip 
(or at least I think it's a clock chip). Enabling the oscillator 
testpoint doesn't do a darn thing (well, the control/setting latch U7 
changes state so again the microcontroller is doing something). There is 
no activity on any of the pins on the chip.

It is getting power (it's not a problem with the NiCd battery).
 
I suspect the chip. Has anyone come across it? It may be a common digital 
clock/calendar chip, or at least related to one (if it is HP-custom). 
It doesn't seem to be particularly designed for a microprocessor bus -- 
the output may be for direct driving 7-segment displays or maybe a 
multiplexed BCD output to link to a display decoder/driver.
 
Thanks in advance for any help.
 
-tony