Aston Martin Virage. Electronic Info Centre problems.

[Geordie McBoyne]

Shown in the attachments are two PCB assemblies from the dashboard of the 1990 Aston Martin Virage.
Although the car has only done 44,000 miles the odometer has taken on to itself to display 98,000 miles.
There must be some method of returning the display back to the correct mileage.

According to some discussion on the AMOC forum a known problem has been the the Siemens TLE4260 low dropout voltage regulator.
I've checked that component and the 5 volt output is absolutely clean. It's actually 4.98V.
The manufacturer of the unit is evidently no longer in business.  A firm called Kemitron Automotive.

I've reassembled the unit and will take it back to the Aston Workshop later today.

Geordie McBoyne.

[Mark Hennessy]

Looks like a nicely constructed unit. Unusual to see IC sockets in automotive electronics.

I wonder how the battery is doing? 25 years is a long time for a lithium cell, but there are reports of them lasting that long. Pretty sure they are guaranteed for 10 IIRC...

[Nick]

The DS1287 is a well known problem unit when its battery starts to run down...

See http://www.mcamafia.de/mcapage0/dsrework.htm
and http://www.classic-computers.org.nz/blog...y-chip.htm

The problem is in the 50 bytes of RAM in the unit that are protected by the lithium battery - as the battery fails, their content becomes corrupt.

The standard replacement is the DS12887-series - however, the RAM will be blank

[ppppenguin]

I've used those Dallas clock chips in my designs for clients. That was some years ago. I doubt that any are still working.

[Refugee]

I used to work in a printer repair workshop in the 1990s and we used to have to change them regularly.
Compaq were the worst culprits for fitting them.
I am pretty sure you can still get thru hold RTC chips so that you can add a little bit of strip board and a watch crystal but that hack looks pretty swift making it more attractive due to the amount of time it takes to build a new clock.

[Geordie McBoyne]

Many thanks for your input. That Dallas "real time" chip is new one on me, I have to confess I have never come across it until now.
I searched the PC boards for the back-up battery, never suspecting that the back-up battery is inside the IC. I'll contact the Aston Workshop tomorrow. This could be an end to the problems they are experiencing with this info centre module.
The Virage dates back to 1990, it could be possible that later models such as the DB7 could employ electronics employing the DS1287.

Geordie McBoyne.

[ppppenguin]

As designers we used the Dallas chip as a very simple and economic solution. We reckoned the equipment would be well past its normal service life before the battery failed. In some cases this was a mistake.

[Mark Hennessy]

The "fun" varies according to what the designer chose to store in the RAM. For test gear, that could be calibration constants, etc. If you're lucky, you can read the contents with an EPROM programmer...

[Refugee]

I once had to repair a Genicom printer that had blown a chunk out of a processor chip. On investigation it turned out to be a little more than just a processor as it was also programmed with the firmware.
I first looked for a copy of the firmware in the extensive archives we had at the time and found nothing. With a second glance I decided it was worth having a go at reading it with the programmer and the file copied without any errors. I ordered a new blank chip from Farnell and loaded the data into it and it worked even though the processor had blown up in the same package right next to the firmware ROM in the old one.

[FIXITNOW]

some of these RTC's you could snap the tops off to replace the battery remember doing it long ago on an old 286 pc

a quick search found this
see here
http://www.betaarchive.com/forum/viewtopic.php?t=22000