Electronics > Metrology

Advantest R6581 8.5 digit DMM mini teardown/repair

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deadlylover:
Here's a mini teardown of the Godzilla of multimeters, the Advantest R6581 8.5 digit beast from Japan.

It's basically a baby 3458A. The R6581 has auto cal and 2 source artefact calibration, basic 10VDC 1 year spec is 5ppm. From what I've seen it has 2-3 times worse noise and linearity than the 3458A...but it's 2-3 times cheaper on the used market. There's a good review and teardown from our friends at 38hot, very interesting read. ^-^

Mine has developed a fault on the current ranges, it seems that the 1000mA Range relay wants nothing more than to spend the rest of its life together with the 0.1Ohm shunt, it's latched on forever and ever. The unit is just about 18 years old now, can't say I'm surprised.  :-DD

Only a short teardown today, I just needed to know what relays to order and I'll be taking more pics during the repair.

Not much screwing around was needed, 2 to take the covers off, 1 for the shield and 3 for the AC board.





Above is the AC board, only the R6581 has this option, the R6581D/T models are DC only.



The current shunts are on the upper right. Lots of nail polish and AE hermetic sealed resistors (?) dotted around the place.



It's got an LTZ1000 reference, not the A version! Set to 65C methinks.

That's it for now folks, I'm going to investigate if the relay is stuck on or if it's just under orders from above. I'll be replacing some of the electrolytics and relays while I'm at it. Sourcing them will probably take quite a while... oh boy.

ManateeMafia:
Thank you for the pics. Do you have any of the manuals? It seems information on this beauty is rather scarce.

deadlylover:

--- Quote from: ManateeMafia on March 14, 2016, 10:07:46 pm ---Thank you for the pics. Do you have any of the manuals? It seems information on this beauty is rather scarce.

--- End quote ---

I uploaded it here, how's your Japanese?  >:D

I've bugged Rohde & Schwarz to see if they can give me any more info, they're the Advantest distributors in Australia.

TiN:
Moar pics, please! Can I steal them?

Perhaps after repair you may like to participate in some comparisons for 8.5-league?
Currently comparison pool likely to be is 6 x 3458A, 3 x 2002, 2 x 1281 and perhaps 7081 :).

quarks:
Hello deadlylover,

looking forward for more to come.
I really like the R6581 because it has artifact calibration as the 3458A but a much more userfriendly UI.

Thanks for sharing
Bye
quarks

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