Electronics > Metrology

Valhalla 2720GS

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I was very happy with  a Valhalla DC standard 2720GS but unfortunately it died in two steps : I lost the differential voltmeter ("DVM repair" as on the one offered now on Ebay) and now "Reference repair". After a lot of tests including the various stacked power supplies, I suspect the Pal deconding chip on the CPU, an EP900. Did anybody read it ? I can read it on a chip programmer but, of course, I down know if it is a good or wrong JEDEC file.
Another question : does anybody know the default password to reset the 2720GS to the factory calibration default state ?

I don't have any information on the 2720GS.

But I'd love to see some pictures of it! (And so would other people that might be able to help more than I can)

Same here, one of few units using statistic voltage references.

That pal is like simple version of CPLD, so it's just couple logic gates in there probably.
In theory should be possible to replace it with some bodged logic circuit, if you can find out what are input signals, what are outputs and what
function that PAL was supposed to do. These may have security bit, so even if somebody have working 2720GS, they may not be able to read it.

Tear-down hi-res photos would be gold.

I would also require pictures.


Some pictures and documentation  before the crash...


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