HP34703A Multimeter Module Service Manual?

[rjmusto]

Hi Guys,

I have a tidy looking HP34740A display unit with a HP34703A multimeter module that I am currently trying to fix.

Turns on ok and the checks I have done so far suggest the display module is ok. But the signal module, the multimeter, is not responding much at all. Some pretty random things happen when moving switches around (they have all been cleaned). So have been hunting around for a manual but no luck so far. I have got a copy for the display unit and it includes the HP34702 meter, but not this other version.

Has anybody got a copy for the HP34703A?

Thanks.

[kevinaston1]

The HP service website says it is covered in the HP3470 service manual


Kevin

[rjmusto]

Hi Kevin,
Problem is though, it ain’t there. I have downloaded two copies of the 3470 manual and, although it mentions the 34703 meter as an option, no details are included.

It gives detail for the display unit, battery unit, BCD unit and the 34702 meter, but not the 34703. Unless the file has been truncated in some way and this bit is missing?

[rjmusto]

Looking on eBay, I’ve just seen two copies of the physical manual. One has chapters just like the downloadable version I have with no 34703, but the other has a different chapter sequence and clearly does include the 34703.

So seems I need to try and find the right version, or buy a paper copy.

[factory]

The original manuals for these, are a folder with the individual section/parts that make up the options the customer ordered. Same with the 3480 series DVM.

The most common input module seems to be the 34702A, I've have several of these, much fewer custom parts & hybrids than the 34703A shown here; https://www.barbouri.com/2021/10/29/...dca-ohm-meter/

Seems Artek have a paid for pdf of the 34703A, available here https://artekmanuals.com/manuals/hp-manuals/ or on ebay, it might be worth asking if it covers the serial prefix of your module, before thinking about buying.

I also have two broken 34750A display modules, one has a missing reference hybrid & the other ref hybrid is faulty, the +/-1V ref in the 34740A display module seems to be all discrete parts.

Note with both the 34740A & 34750A, the on/off switch does not switch the mains, it switches the regulated DC. On mine I noticed the voltage on the main smoothing capacitors with no load, is quite close to the rating of the capacitors, several caps have failed in the meters I have.

David

[rjmusto]

Thanks David,
Some useful tips there. Never thought of checking the no-load voltages.

And yes, of course, Artek. They do have the right manual, so have ordered one from there.

Ralph

[chriswood1900]

This may be of some use to you https://www.barbouri.com/2021/10/29/...dca-ohm-meter/

[rjmusto]

Thanks