Buyer Beware eBay 732a

[MisterDiodes]

Not sure if this goes in Metrology or Buying and Selling - but I figured this might get more eyes in this section.

Be careful of this:

http://www.ebay.com/itm/Fluke-732A-Reference-STANDARD-/302176388032

If these are possibly what I think they are, these -might- be some units disposed of by a university lab in Washington state that were deemed UN-repairable by Fluke.  The reason I say that is they look pretty close to what was being auctioned off at a surplus sale last year by the state, and the 731b by the same seller looks very, very familiar also (although I didn't record serial numbers from what I saw last year at auction).  Some of what I saw last year in person had a CAL REJECT sticker.  In other words: There's a reason these were being disposed of, maybe.

I have tried contacting the seller several times regarding the condition of these units, how they were stored, drift rate logs, what does output voltage measure (and what equipment do they have to measure, etc.).  So far no real answers other than "They are working".

Now it could be that they output a stable voltage, but outside of Fluke specs.  The trouble is if you get a drifty, noisy unit then you're almost always out of luck unless the power supply caps are shot.  Fluke will not repair 732a's. 

Be very careful about these and ask questions before buying.  They could be perfectly fine but it's odd the seller would run across so many "working" 732a's and 752a's all at once, and are selling at that price.

Also note that the 732a was listed as a "Divider" until I brought it to the seller's attention.

I guess the upside is you do get a 30-day warranty, so the news isn't all bad I guess.

Just keep your eyes open on this one.

[TiN]

He has 4 x 752s too.

While I agree one should be cautious buying old standards off secondary market, CAL REJECT wouldn't may mean much. If original owner didn't desire to get standard back in spec, they wouldn't pay for repair/service required if 732A failed first Fluke calibration. Can be as simple as bad caps or dead batteries.

But I'm not in the game to find out. Price is high, but in range for someone desperate. 732A are quite similar to 732B, just in much bigger footprint and bit less strict specs.

[MisterDiodes]

...On the other hand, it's fun to track the history of these units even when the seller has no clue what they are, or won't even answer questions about where they obtained the unit:

For instance this seller doesn't appear to answer any questions:
http://www.ebay.com/itm/Fluke-732A-DC-Reference-Standard-120V-Free-Shipping-/361849050442

But apparently was owned by Harris at least until May of 2016 (The yellow asset number on the front is a dead give-away, as are stickers):
https://www.bidspotter.com/en-gb/auction-catalogues/charleston-auctioneers/catalogue-id-bscch10089/lot-03d407b8-2732-4cf1-aef3-a5ee0150d10a

Looks like it was working enough to earn a Cal sticker to 12-2016... Maybe.  I have seen auction houses and "eBay equipment dealers" 'updating' those stickers on their own, though. Something else to watch out for.  If a 732a/b doesn't have a cal sticker done by Fluke, be careful.  Fluke will tell you for sure if they cal'd a unit or not.

I 100% agree... These could be fine, they could need batteries or caps, they could provide a stable output but would have drifted too far out of range for the pots and jumpers to compensate for, etc. 

[PartialDischarge]

This thread made me look for 10v references, a bit out of topic but which one would you go for ?

http://www.ebay.com/itm/10VDC-003-Precision-Voltage-Reference-Standard/282156304382?
http://www.ebay.com/itm/10-Volt-10-V-VDC-Voltage-Reference-Standard-Nulled-to-Fluke-732A-or-732B/261499015291?

The latter doesnt give info on the calibration of his equipment

[guenthert]

This thread made me look for 10v references, a bit out of topic but which one would you go for ?

http://www.ebay.com/itm/10VDC-003-Precision-Voltage-Reference-Standard/282156304382?
http://www.ebay.com/itm/10-Volt-10-V-VDC-Voltage-Reference-Standard-Nulled-to-Fluke-732A-or-732B/261499015291?

The latter doesnt give info on the calibration of his equipment

Can't say much about the first unit -- I do have the 5V reference ("DMM check") from the same fellow, which works as advertised.

The 2nd one is more, err, "interesting":
https://www.eevblog.com/forum/metrology/calibratory-d-105-dc-precision-voltage-reference-standard/ 

[HighVoltage]

Although it is tempting to get a 732A, I have heard too much about people who bought one and it drifted so much, it was useless.
It seems to be a high risk at that price level.
Another option would be to buy all 7 of them, characterize them and keep the best one.
But even then it seems a gable.

The same seller also offers some 731B
http://www.ebay.com/itm/361862138662
 

[MisterDiodes]

A working, well-cared for 732a...emphasis on the "working" part... can run as well or better than a new 732b in terms of overall stability, regardless of spec sheets. We've seen them 'stay put' in spec for decades without touching the adjustment pot, and the better ones won't drift 0.5 ppm / year.  If you have room for the larger box, the 'A's can be very good performers and you can keep several repaired & in stock for less than a single new 732b.  The basic Vref circuit is very similar between the A and the B, but the B is certainly easier on rack space.

However we're close enough to Fluke to drive the A's in for cal ourselves while hot, which is a big consideration.  If you have to ship to Fluke for cal, then the 732b is easier to keep in cal.

The problem with a lot of "test equipment" dealers - which for the most part don't really know what they have - will keep a 732a/b stored cold in a non-temperature controlled warehouse somewhere.  These units don't like that, and you can wind up with a drifty unit for sure.  These 732a/b respond well to loving care and attention to keeping them powered up.

[MisterDiodes]

I did get a response from the seller when questioned on the 731b:

"It is working"

I guess that's open to some interpretation...

[HighVoltage]

I did get a response from the seller when questioned on the 731b:

"It is working"

I guess that's open to some interpretation...

Biggest problems on the 731B are the batteries, the power switch and transformer.
All easily repairable.

But there must be a reason that Fluke is not even repairing the 732A standards.
May be it is much more difficult to repair a drifting unit.

My preferred one would be the 732B but they are almost never available for sale or outrageously expensive.
 

[TheSteve]

My preferred one would be the 732B but they are almost never available for sale or outrageously expensive.

Wouldn't we all prefer a 732B? I know I'm willing to dedicate a corner of the basement to keep one warm and cozy.
I'd also like 742A-10K etc.

Sheesh look what you guys have done to me. I can find cheap 3458A's - but not cheap standards.

[Echo88]

Comparing Datron 4910/11 and 732B: which one is considered more stable on 10V according to experience? Since they use different zener to 10V scaling techniques.

[TiN]

It's incorrect comparison. 4910 vs 734A is correct one. In the end it boils down to whichever bank reference bank has more known history, given both are stable. Surely 4910 is cheaper, smaller and easier to service. Even if LTZ modules in 4910 goes boo, with 1K$ you can just replace all them with new parts without problems. With Fluke LTFLU you stuck on unobtaniums custom parts/hybrids. 734A allows you longer life on battery and individual cell service/usage though.

[Conrad Hoffman]

I've little doubt I could repair most anything wrong with any of them, but eBay sellers tend to think they have gold when they have pot metal. I'm never going to pay high prices for something with an unknown performance history that might require weeks of cumulative work to bring back to good health.

[VintageNut]

I've little doubt I could repair most anything wrong with any of them, but eBay sellers tend to think they have gold when they have pot metal. I'm never going to pay high prices for something with an unknown performance history that might require weeks of cumulative work to bring back to good health.

I agree. The days of "eBay bargains" for test equipment are mostly gone. You can still find a bargain once in a while. Sellers think that just because they have a piece of equipment, it is worth the maximum possible.

I have purchased two 731B units for a fair price each and am happy with both. At the time I purchased, there were quite a few for sale over some months. Now they seem to be rare.

I purchased a KE2000 that died a week after I received it. That was a wake up call to realize that a working used instrument can die suddenly no matter how well it behaves when the seller powers it up and writes the description for the auction. As TiN has stated, any ebay purchase should be assumed to be in need of repair.

I have been pleasantly surprised by some used test equipment that has worked perfectly from the first day and continues to work.

[TiN]

That's why I buy dead gear. At least it's already dead, so no need to worry about if it's good or not 
Wish all better deals next year 

[Theboel]

I agree with TiN. The most interesting parts usually its comes with low price