Error 1 and error 4 on the HP 4275A

err1, Error in ZERO offset adjustment. The value of the residual parameter present in the measuring circuit exceeds the offset control limit.

I think that means the instrument needs servicing.

err4, Error in measuring circuit configuration. It goes on to describe an open or short in the test fixture (i.e. improper connections to the four BNC signal jacks), hinged cover open on 16047B, or a DC-bias measurement-range conflict.

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 Thanks,
    - Win

Hi Win on the issue of err1. I have a HP 4275A and HP 4274A both give the same results. However, I am using four bit of wire. The four inputs are Lcur, Lpot, Hpot and Hcur. Am I correct in assuming that Lcur and Lpot are shorted and Hpot and Hcur are also shorted at the point of measure e.g. at the DUT.

Thanks

Wayne

"W>>

They use coax, with all the grounds connected at the end.

Yes.

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 Thanks,
    - Win

HP

are?

In addition to Win's response, if I could ask: do you get this err message with the factory zero meter test fixture plugged in? It affixes right to the BNC connectors on the front of the instrument. If you have that fixture, try that first as a reality check, and screw both clamps closed so they touch. That might solve your problem. This meter is picky about fixturing. The other factory fixture has white coax cables that seem to get damaged easily, so it's better to do a GO/NOGO check with the fixture without the coax cables -- less to break.

If you are getting those error messages with the 0 m factory fixture plugged in, and can't zero, it's possible you need repairs. Wait for the manual and read it carefully first. In addition to a troubleshooting flowchart, there's also a lot of useful measurement information in there.

Good luck Chris

Hi Chris

Ahhhh. I do not have a factory zero meter test fixture. Do I need to get one or can I live without one? What are the part numbers of both attachments?

Cheers

Wayne

to get

These meters always came with a standard test fixture, which plugged directly into the 4 coax connectors on the front panel. It's a small white box with 4 female connectors. You can use it to measure components directly. It's not made specifically for zeroing the meter, although you can use it for that. The meter won't zero out without having some fixture capacitance there (and also having the high current connected to high potential and low current to low potential too, I believe).

Look around and see if you have this fixture. As I remember, it's a small (approx. 6" X 3" X 2") white metal box with flat recessed gold-plated clips on the top, and two knurled thumbscrews on the front to lock in components or small conductive contact blocks.

The advantage of using the factory fixture is that it has a known impedance which the meter _should_ be able to zero out. As I remember, there is a switch on the front of your meter which has two positions --

0 meter or 0.5 meter (length of the fixture coax to compensate). I preferred to use the 0 m setting and this fixture (you can't plug in the fixture I'm talking about without switching the front panel switch to 0 m -- it won't fit) because you didn't have to worry about intermittent coax on a quick meter check/zero compensation.

When you get the manual, do the self-test sequence -- it may give you more information on what's going on than a zero/fixture compensation cycle can achieve.

A bit of bad news -- on the last one of these meters I used (about 8 years ago, all this is from memory), the symptoms you're reporting were the initial indications of the bitter end. I hope you'll have better luck.

Chris

Actually it's because your parasitics from the Open measurement exceed a predefined usable dynamic range for the instrument. You're supposed to be using a "standard" HP 160xx LCR cable. The open load is know and within the dynamic range of the instrument. Using something else can will result in a compensation value that puts the instrument out of its calibration spec. Pretend this is actually complex impedance instead but basically: C(compensated) = C(measured) - C(offset) where the offset is so big you'll get round-off, etc. and C(compensated) won't be in spec anymore.

Since the 4274 and 4275 are virtually identical (firmware-wise) and both use only 8-bit microcontrollers, there's the same finite dynamic range and round-off characteristics on measurements with the same fixturing, thus the same error condition results.

M

I'm not sure what message you're responding to since it doesn't show up on my server, but I'll comment that it's not unusual to get these errors while using the proper standard hp fixtures. I don't know but wonder if the fix can be as simple as an internal adjustment. If my service manual, which has disappeared, turns up, maybe I'll find out.

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 Thanks,
    - Win