HP98035 Real Time clock and AC5954N clock chip

[CuriousMarc]

All HP fans in general and Tony in particular,
I have the exact same problem. HP98035 real time clock module
(http://hpmuseum.net/display_item.php?hw=168), plugged into a HP9825T
(http://hpmuseum.net/display_item.php?hw=171), accepts commands, reads back
all 8's. Battery is new, is charging and at the correct voltage.
Documentation says "never run the module without the battery or it would
damage the AC5954N clock chip". When I got the module it had not battery in
it, so this is what could have happened. Tony, did you eventually repair
your module or find some data on the clock chip?
Marc
 
 
List:       classiccmp <https://marc.info/?l=classiccmp&r=1&w=2> 
Subject:    AC5954N clock chip (I think)
From:       ard () p850ug1 ! demon ! co ! uk (Tony Duell)
<https://marc.info/?a=104957097300008&r=1&w=2> 
Date:       2001-08-26 22:55:32
<https://marc.info/?l=classiccmp&r=1&w=2&b=200108> 
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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