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Nice little DMM from the 70s, back then my first digital instrument, fresh out of the box. Out of curiosity, how did the hybrid get damaged? I'm guessing some sort of an input overload, although I put mine through the paces making the usual rookie mistakes like 120VAC into the Ohms range, but never had any problems besides maybe a couple of blown out 1/16Amp input fuses.

Hello Alex,
With one of my HP-3476A DMMs, like you, I did try to measure the resistance of a transformer winding when the mains was already applied. The other one arrived dead. I know the hybrids are faulty because when I substitute from one of my good 3476As, they work OK.
I have also had the 1/16 A fuses blow, and so I have a stock of new Littlefuse replacements.
Any idea where I can find replacement hybrids in GWO?
Cheers, Brian


On Wednesday, 1 July 2020 11:58 PM, Alex said:

Nice little DMM from the 70s, back then my first digital instrument, fresh out of the box. Out of curiosity, how did the hybrid get damaged? I'm guessing some sort of an input overload, although I put mine through the paces making the usual rookie mistakes like 120VAC into the Ohms range, but never had any problems besides maybe a couple of blown out 1/16Amp input fuses.

Brian not really sure where you could find this hybrid, and as far as I know the HP parts stock that George has is mainly centered on the HP3468/3478 meters. I would try on ebay for a 3476 that shows obvious external problems with missing or broken parts, or a housing in bad shape with lots of dirt or wear etc like it fell off a moving vehicle. I've occasionally seen in the past a few showing up that more or less fit this description. Maybe that way you might be able to find a cheap unit with a good hybrid, plus any other usable extra spares. Also sometimes it helps to find out how long the item has been listed with the [Time: Newly Listed] search option, and if its been around for a couple of months with no takers start a friendly conversation with the seller and eventually you might possibly end up still getting it at a decent price. I still remember some 10 odd years ago when 3476's going for $20-25 where still a quite common sight on ebay. But nowadays with those damn Led display vintage sellers inflating prices just because they feel like it, prices are now more like in the $50 to $100 sometimes or even higher range, depending on condition and included accessories. Still I would put up a search for a "hp3476 parts" unit and set the price trigger to under $50 which might be a good starting point, and who knows maybe something usable will come up at the right price. Sometimes you can get lucky, not too long ago I got a fully working but sad looking HP3468A listed for $35, I offered $25 and seller readily agreed. In the end besides a broken carry handle it really only needed a thorough cleaning. Not bad for fully operational 5.5 digit DMM with still very accurate readings. BTW I posted a thread here on that $25 3468A restoration process. Hope that you manage to find that spare hybrid and get the 3476 going again.

The 3476A was designed before I joined HP.? I do have some working 3476A meters but not so sure about the hybrid.? It will take me some time to get unpacked.

I suggest we carry this conversation on the 3478A? calibration thread or the poorly arrived 3468A thread started by Alex.? ?I have posed more frequently on those threads.? I like it all to be in one? or two places.

George Hnatiuk? ?July 2, 2020

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