EBAY: Many faulty hp/agilent 34401a multimers

[FireFlower]

Yeah, those look very bad, might be from Nokia South-Korea factory from 2014 auction and most equipment that came from there after auction was horrendous, I still see nightmares opening those machines to clean up so we could use them... Actually the work still continues, lots of moisture damage and large machines had not been serviced long time 

[TiN]

...
Just see what TiN has had to do with his 3458A from the same seller. New transformer, new voltage reference, repairs to power supply boards, repairs to A/D boards - replacement of A/D board. (Unobtanium parts). Anyone would think someone had took all the good boards and shoved in all the shit ones, even forgetting the VREF totally, and sell it on...

Well, to be 100% fair, I got what I asked for that price point, really. I'm not seeing how anyone could get properly working 3458 for less then 3K$ in any way, unless someone just give it as a generous gift. Many of those "good" 3458 up for sale now are there for months, and still might have number of hidden issues, like drift of ADC or some intermittent issues. I just chosen the hard way. Would I do again knowing all what I do now? Yes, I think so, it's crazy project to do.

P.S. Not saying those 34401a worth it, though. Completely different class of device, with plenty of better/cheaper alternative around.

[hendorog]

I took a punt on the as-is one mentioned above, and put in a low offer.

It has just arrived this morning and it actually does work and show reasonable values - so far anyway!

The display is pretty dim, and only just readable in the menus. However it is OK in my environment when actually measuring values.
I had a quick play in the menu without knowing what I was doing:- Tests pass, there are no errors and calibration message shows a date in 1993.
Cal count is 146 if I am reading it right, which seems pretty high.

Inside it looks as you would expect for an old instrument. No water damage at least.

Shipping was expensive (cost more than the meter), but it was DHL and so arrived very quickly.
Total cost was $150 USD including delivery to New Zealand.

[Macbeth]

The weird dots on the display put me off that one. Are they still there?

[hendorog]

The weird dots on the display put me off that one. Are they still there?

I'm not in front of it now, but yep I think they are.
The display isn't as bright as it looked in the picture on ebay either, but I think that is just the effect of the camera.

Interestingly I see this one also has the dots:
http://www.ebay.com/itm/HP-Agilent-34401A-Multimeter-RAM-R-W-Fail/252179101047?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D34293%26meid%3D128cb9612c0f457aa5d3fa04ae98cb32%26pid%3D100011%26rk%3D3%26rkt%3D10%26sd%3D252179076182

[Macbeth]

Perhaps a trick to wring the last possible life out of a worn VFD is to overdrive it, in which case the very rarely (if ever) used segments like those top part of a colon : symbol dots will be lit up. The bottom dots not so much as they will have been in use as decimal points.

This one http://www.ebay.com/itm/252179072641 looks like they went overboard on the over volt/current hack 

I guess you got the best of an awful bunch, just need a new VFD.

[free_electron]

those dots are caused by leaky VFD drivers. they are TI parts. obsolete and replaced by pericom . i have posted the xref before on the forum.

these are 32 bit high voltage shift registers in plcc44 package. replace em and the problem is solved.

Note : if you have a really old 34401 then the VFD is driven by a upd75xxx custom cpu with integrated drivers . That one is unobtainium....
and the fronts are not interchangeable... a newer 8051 based frontpanel does not work in a machine that needs the upd75xxx based one.

[hendorog]

those dots are caused by leaky VFD drivers. they are TI parts. obsolete and replaced by pericom . i have posted the xref before on the forum.

these are 32 bit high voltage shift registers in plcc44 package. replace em and the problem is solved.

Note : if you have a really old 34401 then the VFD is driven by a upd75xxx custom cpu with integrated drivers . That one is unobtainium....
and the fronts are not interchangeable... a newer 8051 based frontpanel does not work in a machine that needs the upd75xxx based one.

Thanks for the info. I'll check it out tonight and see. This one is pretty old so could well be the latter.

[hendorog]

Perhaps a trick to wring the last possible life out of a worn VFD is to overdrive it, in which case the very rarely (if ever) used segments like those top part of a colon : symbol dots will be lit up. The bottom dots not so much as they will have been in use as decimal points.

This one http://www.ebay.com/itm/252179072641 looks like they went overboard on the over volt/current hack 

I guess you got the best of an awful bunch, just need a new VFD.

Yep - at least its working better than my ex Navy Fluke 8600A (Nicad version) - that thing blew a big cap covering everything in crap and melting the case!

[HighVoltage]

The 34401A even sells well for 351 euros as a used one, when marked as "Keithley" on ebay Germany
LOL

Keithley-34401A-Digital-Multimeter-6-Digit
http://www.ebay.de/itm/281870590929

[MadTux]

Some not so cheap, truely f*cked 3456As, anyone?!?
http://www.ebay.com/sch/m.html?_odkw=&_ssn=bestindustrial&hash=item3ab5af1d53%3Ag%3Am6cAAOSwwbdWOZZd&item=252156255571&_osacat=0&_from=R40&_trksid=p2046732.m570.l1313.TR0.TRC0.H0.X3456a.TRS0&_nkw=3456a&_sacat=0

 

[Vgkid]

I would easily grab the cheapest one, but shipping kills it. Plus who knows the fate of the insides.

[Macbeth]

The 34401A even sells well for 351 euros as a used one, when marked as "Keithley" on ebay Germany
LOL

Keithley-34401A-Digital-Multimeter-6-Digit
http://www.ebay.de/itm/281870590929

It's odd that it went for such a high price... Unless the buyer is going to rely on the listing being wrong/fraudulent and playing that card. I hope not, despite it being guaranteed by ebay policy to work against the seller and award the scam artist.

[MadTux]

It's odd that it went for such a high price... Unless the buyer is going to rely on the listing being wrong/fraudulent and playing that card. I hope not, despite it being guaranteed by ebay policy to work against the seller and award the scam artist.

Probably because HP/Agilent/Keysight/Whatever changed names so often, people are searching for 34401A only, instead for HP 34401A, Agilent 34401A etc separately. Thereby only correct number is needed. Keithley keyword also helps.

I would easily grab the cheapest one, but shipping kills it. Plus who knows the fate of the insides.

Really??? 3456As in unknown, but nearly 100% fixable condition usually go for as low as $60-90 on US ebay. Here, the truely broken one costs 80$ and you have to pay expensive shipping to get an instrument that is basicallly ruined with water/corrosion crap inside.

[Vgkid]

I should have said that I would pay that much if it was not sold by that seller(and located stateside). The Analog Devices cal sticker from 2011 does pique my interest.

[free_electron]

34401 should go for about 300$ in pristine condition.
Agilent has put these things on life support. they are discontinued ( or soon to be )

[HighVoltage]

About a year ago, they still sold for much higher prices in the US
Now it seems they sell for more in Europe

[eas]

34401 should go for about 300$ in pristine condition.

Perhaps, but they seem to be going for more than that lately.

Agilent has put these things on life support. they are discontinued ( or soon to be )

Dec 1, 2016.

[Pannenkoek_met_een_lampje]

those dots are caused by leaky VFD drivers. they are TI parts. obsolete and replaced by pericom . i have posted the xref before on the forum.

these are 32 bit high voltage shift registers in plcc44 package. replace em and the problem is solved.

Note : if you have a really old 34401 then the VFD is driven by a upd75xxx custom cpu with integrated drivers . That one is unobtainium....
and the fronts are not interchangeable... a newer 8051 based frontpanel does not work in a machine that needs the upd75xxx based one.

Bought a 34401A on Ebay and it seems to have this hardware fault. The driver IC is between the screen and PCB so I can not see the text on them. Is there a way to determine what is in there without taking it apart? there are some texts on the screen module like 0795 which looks like a data code to me. the text 34401-66502  and there is also a sticker with a bar-code and the code 5CF0052. I am afraid I can see a 42 pin trough hole dill part ... does this mean it is unrepairable?

[Inverted18650]

Hey mate, this thread was last updated in 2015. Not sure anyone will come back, maybe start a fresh thread.


(no not..haha, glad I was wrong).

[HighVoltage]

Is your 34401A really old with only red 4mm input color rings?
Then it is most likely the very old type.

[coromonadalix]

HP brand are they the ones with unfindable and unreplacables vfd chips    if you get the model keysight or agilent with red and black input plugs  you may get lucky to have a repairable  one  

[corn11]

Not necessarily, only the early ones have the old front panel board with the NEC µC. Those front panel boards have another part number 34401-66502. If you look in the backdating section of the service manual you can (probably) identify the DMMs with the old FP by the serial number.
Otherwise the red rings on the negative jacks as HighVoltage mentioned are probably also a good indicator.

According to the service note 06 it also seems like that you can replace the old panels with the NEC µC (34401-66502) by the new ones (34401-66512) if you update the firmware:
http://literature.cdn.keysight.com/litweb/pdf/34401A-06.pdf

[Stray Electron]

If someone who sells primarily test equipment sells units "as-is" its bad news.....

  A-men to that!   That's why I NEVER buy anything "as-is" from Tucker or other major equipment dealers. You can be SURE that the units have been stripped of anything usable before the carcass gets dumped on E-Greed.

[Zucca]

But user zucca can still have one for   sale https://www.eevblog.com/forum/buysellwanted/fs-34401a-window-front-panel-display-34401-49311/msg411737/#msg411737. Zucca live europe now I think.

It was sold long time ago, sorry.