Toshiba tecra 8000, not booting, no display, LED blinks code 82h BGVSNS, which c

[cgtueno]

Hi

I'm trying to resolve a fault on a Toshiba Tecra 8000.
The unit does not boot, no display, LED blinks code sequence for 82h
which is a BGVSNS voltage out of range (under volt: <1.02V) fault.

The external PSU checks out fine under load, and has been tested with another Tecra 8000.

Clearly this is a motherboard related fault (probably the circuitry on the power bus itself).

The unit behaves in the same manner with no battery, or removable modules installed.

Any suggestions on:
1) which components to inspect/replace on the motherboard
2) where on the motherboard the BGVSNS voltage may be measured

Additional question:

1) In normal operation will the Tecra 8000 boot with no RTC and Memory backup batteries attached ? Can faulty RTC or Memory backup batteries cause a BGVSNS fault ?

Regards

Chris

 

[cgtueno]

Notes:

Unit has been disassembled and inspected.
Unit exhibits same behaviour with RTC and Memory batteries removed

C.

 

[cgtueno]

Update

I have located the source of the fault (in my case) that reports as a blink code 82h (which is believed to translate to "BGVSNS error" according to www available information).

The CPU daughter card (containing the PII processor and cache) that plugs into the base motherboard in the Tecra 8000 appears to be at fault.

Replacing the CPU daughter card with an available (tested) replacement restored the unit to full working order.

Subsequent testing of the original ("faulty") CPU daughter card in a known working Tecra 8000 resulted in the generation of the same error 82h blink code report on that machine.

Interestingly there are considerable differences in the construction of the two the CPU daughter cards in the two Tecra 8000 machines. One card appears to have a number of ICs, which may be cache, which are not present on the second card.

I hope the above information aids anyone with a similar problem in the future.

Chris

PS. I'm still interested if someone can can shed some light on where I can measure the BGVSNS voltage on the motherboard for the Tecra 8000.

(The Tecra 8000 will boot without both the Memory backup, and RTC batteries(with the obvious operating limitations)