Author Topic: Repair worklog : Old rusty HP 3458A (Read 252926 times)

ManateeMafia · « **Reply #375 on:** November 19, 2015, 01:44:28 am »

The only thing I can see that is remotely questionable is the missing screw on the A9 reference board based on the photos from xDevs. Air drafts around the LTZ1000?

TiN · « **Reply #376 on:** November 19, 2015, 07:34:26 pm »

It did not go away...And likely a very bad idea here... I wish to come back to simple and easy Keithley's now!

Macbeth · « **Reply #377 on:** November 19, 2015, 11:45:32 pm »

I knew it! Take out the ASIC's and swap them - but make sure to soak them in the tears of gypsies first!

ETA: That's not some lifted pads on some of those pins I hope?

ManateeMafia · « **Reply #378 on:** November 20, 2015, 02:13:50 am »

All right. I did find one more item......

Your initial pics showed the blue wire connected to the internal frame and the gray to the outer. Your final pics show them swapped around.

https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/top_open.jpg

https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_top.jpg

The silkscreen on the A1 even tells you how to hook them up.

Yes, it appears you have it connected properly.

TiN · « **Reply #379 on:** November 20, 2015, 04:14:11 pm »

Decisions, decisions....

Jwalling · « **Reply #380 on:** November 20, 2015, 04:18:08 pm »

Quote from: TiN on November 20, 2015, 04:14:11 pm

Decisions, decisions....

Hi Tin,

Do you have a picture of the top of the chip?

ManateeMafia · « **Reply #381 on:** November 20, 2015, 04:31:51 pm »

Put the one suspected of throwing the error in the other board first. In case the err 1 was related to some other component that wasn't changed. Plus, the other board should have all HP screened parts.

Do both boards have the same cpu markings? I don't know how many versions of the inguard fw have been released.

Macbeth · « **Reply #382 on:** November 20, 2015, 04:49:28 pm »

If swapping them around only causes the same faults to follow them, then maybe another answer is RAVERS - Redundant Array of Very Expensive Rare Silicon.

Determine the areas of which ASIC work/not and create a riser board with both chips routing the good pins of either chip to the socket. Hell, maybe some pins other than power and grounds can be paralleled to provide further redundancy!

Of course if swapping them and the faults stay with the original boards then the chips must be good and its a board fault.

TiN · « **Reply #383 on:** November 20, 2015, 05:14:07 pm »

No, it's this bastard. Installed "ERR" chip into drify A3 PCB, did not change anything else , and yah, instant ERROR 114 - multislope or balanced rundown convergence.
So this dreaded error comes from U180, that's clear now.
I did measure resistors accessible from pins, they all were okay (will post more detail later on both chips).

Now time for opposite swap, install drify ASIC into my old A3. If it will work , than drift came from other part on A3. But I doubt that, and there is a reason why.
I took very good look on drifty ASIC , and it seems it had pencil handwriting "Drift -1.09". $:-\$

TiN · « **Reply #384 on:** November 20, 2015, 05:23:46 pm »

Here's top of chip. It's barely visible, but you can help with imagination..

TiN · « **Reply #385 on:** November 20, 2015, 05:40:06 pm »

Soldered Mr.Drifter into my old original bodged up A3. NPLC 100, no errors, all working.
Let's have my little python snake run some GPIB commands and see how it's behaving. Last hope that drift was caused by something else on A3...

Macbeth · « **Reply #386 on:** November 20, 2015, 05:41:55 pm »

Good luck! Just because they wrote drift 1.09 on the chip doesn't mean it is the chip at fault, just the most suspect.

ETA: Actually looks like Drift=I.09 to me, so = current * .09?

TheSteve · « **Reply #387 on:** November 20, 2015, 05:42:03 pm »

Fingers crossed for you!

TiN · « **Reply #388 on:** November 20, 2015, 05:48:17 pm »

Chip was soldered before, so it's pretty high chance it is the cause...
Anyhow, we will know tomorrow morning for sure.

ManateeMafia · « **Reply #389 on:** November 20, 2015, 06:04:04 pm »

This will be an opportunity to create some burn in procedures for those of us that will potentially buy 3458A parts or whole meters.

chinapp · « **Reply #390 on:** November 20, 2015, 08:03:41 pm »

attach is the pic of the teardown of the ASIC 1NC1-0017,some people in China had researched much on this ,the conclusion is that the most suspect is this BIG IC,the precise resistor in this IC become unstable or drift

,and the bad thing is there is no spare for this

TiN · « **Reply #391 on:** November 20, 2015, 08:12:13 pm »

Interesting, do you have a link to thread?

I don't think it's precision resistor are issue in this chip. I had measure them (at least ones which connected to pins) and they read OK values. I also heated up chip by touching it with soldering iron to see if it stable with temperature, and got just a little change, so I assumed temperature stability was OK too.

I'd suspect those current balancing die instead.

chinapp · « **Reply #392 on:** November 20, 2015, 09:05:26 pm »

http://bbs.38hot.net/forum.php?mod=viewthread&tid=101360&highlight=%B4%F3%D0%BE%C6%AC

a China bbs, 38hot,in Chinese character

the thread is also discuss on how to repair this IC, the black zone is the precise resistor

chinapp · « **Reply #393 on:** November 20, 2015, 09:09:48 pm »

Quote from: TiN on November 20, 2015, 08:12:13 pm

Interesting, do you have a link to thread?

I don't think it's precision resistor are issue in this chip. I had measure them (at least ones which connected to pins) and they read OK values. I also heated up chip by touching it with soldering iron to see if it stable with temperature, and got just a little change, so I assumed temperature stability was OK too.

I'd suspect those current balancing die instead.

there are several resistors inside that need match in good value, do you use a precise multimeter to check all the resistors ? especially the run down and run up resistor

Theboel · « **Reply #394 on:** November 21, 2015, 12:25:10 am »

Ok I understand We can use the "active" parts of the "Hybrid IC" and arrange the resistor array outside but I do not understand how to find a suitable resistor value ?

TiN · « **Reply #395 on:** November 21, 2015, 04:29:04 am »

Hmm...

I'll cleanup A3 board a bit, remove sticking out extra caps from it, assemble box and we let it sample for a day or two..

TiN · « **Reply #396 on:** November 21, 2015, 06:22:00 am »

Self-test failed, Failure 209, Timeout read A/D : 197 (flatness DAC 1V)...

Trying to get make my old A3 board functional..

ManateeMafia · « **Reply #397 on:** November 21, 2015, 06:54:40 am »

Oh no. Is this possibly related to more Elantec failures or just issues with U180?

TiN · « **Reply #398 on:** November 21, 2015, 07:34:17 am »

Perhaps something else on board. I had lot of chips on it changed before.
U180 was ok on another A3 PCB, and this error is on ACV path.
Replaced U112 (I had replaced 848 to AD829 on old board, as did not have 848), Q403, R186 , CR120 from replacement A3, now testing if it will drift on DCV, to clear this parts.

TiN · « **Reply #399 on:** November 21, 2015, 10:15:49 am »

Meh, I give up for now.
Tried U181, checked R181 (resistor which connects AC_AD to U180 ASIC), cleaned both A2 and A3 boards again, nada.
Had cold showers few time, when it started pop few Error 114's multislope rundown convergence errors.

Put all covers back in, will test DCV next week to see how it works. I don't need ACV now. Self-test fails same points, right in the end, where it shows TEST ACDCV 10mV and TEST ACDCV 100mV (sometimes 10mV pass) with same error FAILURE 209 : TIMEOUT READ A/D : Value 195 or Value 196.

CAL DCV, ACAL DCV,OHMs is fine. Tried swapping CAL NVRAMs too (was thinking if constants got corrupt), no change..
Hope one day another A3 pop up on ebay, so I can get back to it.


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Author Topic: Repair worklog : Old rusty HP 3458A (Read 252926 times)

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