Author Topic: Advantest R6581 8.5 digit DMM mini teardown/repair  (Read 66210 times)

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Offline Kleinstein

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #25 on: September 05, 2017, 11:39:35 am »
Also R6581 got a lot of improvements during its production. Some of my early research is here:

It looks like much of the "improvements" are towards lower production costs, not so much better performance.
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #26 on: September 05, 2017, 11:49:40 am »
Yes, it seems so. But the most widespread model is a R6581T, and it is not intended for general metrology. R6581T was presented to market as affiliated equipment for IC Test System by ADVANTEST.
 

Offline Kleinstein

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #27 on: September 05, 2017, 12:01:27 pm »
In some places, like at the input amplifier and the ADC even the new version BMF resistors instead of even better hermetic ones before are very good - I would not expect precision resistors like this at these places. Other meters use more like PTF56 or similar for that purpose. So the changes are saving some money, but would have no significant effect.
 

Offline z01z

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #28 on: September 07, 2017, 07:55:29 am »
Also R6581 got a lot of improvements during its production. Some of my early research is here:
Interesting project. If it helps, I can take pictures of a meter made in ~98 (at least the ref board has 3 hermetic resistors and plastic OPA).

 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #29 on: September 07, 2017, 12:17:46 pm »
Interesting project. If it helps, I can take pictures of a meter made in ~98 (at least the ref board has 3 hermetic resistors and plastic OPA).
Thank you for the suggestion. The most interesting thing is a AC subboard and its interconnection.
Up to this day was reversed an ADC schematic, algorithm of A-D conversion, algorithm of A-D current sources selftesting, fast/normal mode ADC switcing, master voltage reference and all seven auxiliary vrefs too, input MUX hybrid, VDC and Ohms input protection, VDC guard/bootstrap amplifier (partially), VDC artifact switching circuits, main input amplifier (FETs, guard, range switching only), level triggering DAC.
 
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Offline dice

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #30 on: September 30, 2017, 07:30:03 am »
I came by a R6581T on the cheep but all it does is beep at me with no display. From everything I'm reading, and you guys have been the most informative, I should start by looking at the battery. Any further ideas for the beeping?
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #31 on: November 20, 2017, 08:31:18 am »
R6581 have a full description of selftest errors in a plain text mode. But I don't have a programmer for PLCC44 EPROM :'(
 

Offline z01z

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #32 on: November 21, 2017, 05:57:22 pm »
A reader would suffice ;).
The error messages are listed in appendix A.1 in the manual.
 
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Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #33 on: November 22, 2017, 05:12:34 pm »
As expected, it's a VRTX32/68k real-time OS based firmware. But there is no secret menu, hidden codes e.t.c  :(
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #34 on: November 27, 2017, 08:57:55 pm »
The last unexplored places  ;D

P.S. The problem is solved. Thanks to Advantest Research Club.
« Last Edit: December 01, 2017, 11:58:34 am by Mickle T. »
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #35 on: January 08, 2018, 03:10:05 am »
Hi, deadlylover, I met a 6581 who have a selftest error "+224 a/d check5 error" and want to find the manual to see the detail. I noted that you have uplaod one copy in the link ,but I can't download it. Could you help me to send the manual to my email: 13603052469@139.com  ,  and could you give me some advice on how to repair it ?   
Many thanks and Happy new year 2018!
Best Regards,
Szjdb
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #36 on: January 08, 2018, 05:23:06 am »
AD_5 CHECK is a rundown current sources ratio test. Charging surrent switch - Q209, discharging - Q210.
This is the last AD checkpoint, so it is possible, that Q210 is in failed condition.
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #37 on: January 08, 2018, 07:24:27 am »
Thanks a lot! 
Yes the meter has the problem in current measurement and repaired by somebody, who said replace the relay . The test date deviated from the reference r6144 output about 0.8% to 0.06% from 0.1mv to 10v range. My question is can I fix the A/D check5 issue just by inner self calibration or external calibration?

Thanks again!
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #38 on: January 08, 2018, 07:34:31 am »
AFAIK selfcalibration can't fix the AD Check errors. It's hardware problem. Look at the 7461 DMM errors list:
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #39 on: January 08, 2018, 08:41:51 am »
Thank you Mr. Mickle.T !
1. The check5 error occurs some time , not 100% in every power on cycle. If not occuring, does it means the test result is reliable?
2. Is there posibility the eeror is causing by the resistor network THD140? This parts is difficult to find replacement.
I was wondering  if to buy the  meter and can fix it by myself.

Thanks for your help!
Best Regards,
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #40 on: January 08, 2018, 09:00:58 am »
There are many tests (and AD check also) can be launched via DIAG mode menu.
THD140 is a 12:1 hybrid FET MUX and do not have any relationship with ADC and a/d check5 error.
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #41 on: January 08, 2018, 09:44:56 am »
Thanks a lot!
I will try it!
Best Regards,
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #42 on: January 10, 2018, 02:49:23 am »
Hi, Mr. Mickle.T ,
The seller give some more infomation about the 6581.
1. The A/D check5 error is few to occur, 1 in 20 time when power on. That is to say it can be ignored?
2.  The test data are as below:
   source   meas            delta   %         meter range
   100   ma   100.0764   -0.0764   -0.000764      100MA
   10   ma   9.9935   0.0065   0.00065      10MA
   1   ma   0.97925   0.02075   0.02075      10MA
   0.1   ma   0.07177   0.02823   0.2823      10MA
                     
                     
   10000mv   10018.8843 -18.8843   -0.00188843   10V
   1000   mv   1002.125   -2.125   -0.002125      10V
   100   mv   100.4422   -0.4422   -0.004422      10V
   10   mv   10.20681   -0.20681   -0.020681      100MV
   1   mv   1.19438   -0.19438   -0.19438      100MV
    Does it means the issue is not so serious and can be fix by  the self of external calibration?

Thanks !
Best Regards,
szszjdb
 

Offline Terry01

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #43 on: January 10, 2018, 05:33:55 am »
I just had a wee look in on the Yahoo auction site you mentioned. Why are the bench meters going so cheap? Some nice stuff for crazy prices! How does that work out so cheap?
Does it cost a fortune to get them shipped from Japan to like the UK or USA or whatever?
I would never need anything so much as one of these units, I am just learning hobby stuff so a decent handheld meter is more than I will ever need.
Just seems funny bench meters like that going so cheap. What's the catch? I would expect them to go for lots of Wonga!
Sparks and Smoke means i'm nearly there!
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #44 on: January 10, 2018, 06:08:56 am »
Does it means the issue is not so serious and can be fix by  the self of external calibration?

How does that work out so cheap?
The answer is very simple  ;D
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #45 on: January 10, 2018, 06:40:13 am »
Hi, Mr. Mickle.T ,
That's not my case. I really saw the picture in measuring. I just wonder how difficult to fix it . By self calculation or relace Q210 ?

Thank a lot!

Best Regards,
szszjdb
 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #46 on: January 10, 2018, 06:51:20 am »
Integrator switches Q206-210, Q217-221 leakage or fail, PCB leakage/dirt, power supply noise, R213 resistor network fail.
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #47 on: January 10, 2018, 08:47:25 am »
Thank you  Mr. Mickle.T ,
You means to fully fix the A/D check5 error issue, must check the componenent you mentioned above.
But in the case that the meter can pass the self check and get into the normal use ,can the inaccuracy reading issue been fixed by self or external calibration?

Thanks a lot and Best Regards,
szszjdb

 

Offline Mickle T.

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #48 on: January 10, 2018, 08:58:48 am »
Selftest procedure have a very wide tolerance limits. If ADC have a large noise or nonlinearity, selftest will not show an error, but artifact calibration will give an unpredictable results.
 

Offline szszjdb

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #49 on: January 10, 2018, 09:23:43 am »
Fully understand.
Thank you very much!

Best Regards,
szszjdb
 


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