Author Topic: Advantest R6581 8.5 digit DMM mini teardown/repair  (Read 101657 times)

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Offline leighcorrigall

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #775 on: May 06, 2021, 01:02:39 pm »
I took a quick glance at the translation of Chapter 13 and found that it is different from the manual I downloaded from xDevs and KO44B. There is no Figure 1 in my version.

Correct. I added the illustration from the Advantest website so that the readers would know what the A01035 cable model number was referring to in the instructions.
« Last Edit: May 06, 2021, 01:04:49 pm by leighcorrigall »
 

Offline quarks

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #776 on: May 07, 2021, 12:34:24 pm »
just in case anyone is looking for an original AC Option board
I still have one
https://www.eevblog.com/forum/buysellwanted/fs-advantest-r6581-parts-(location-germany)/msg3358518/#msg3358518
just send me a PM
 

Offline leighcorrigall

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #777 on: May 07, 2021, 01:26:15 pm »
just in case anyone is looking for an original AC Option board
I still have one
https://www.eevblog.com/forum/buysellwanted/fs-advantest-r6581-parts-(location-germany)/msg3358518/#msg3358518
just send me a PM

Therefore, reverse engineering of the RMS board is on my to-do list (if, of course, one day I have it).
 

Offline serg-el

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #778 on: May 07, 2021, 03:13:11 pm »
To understand the complexity of reverse engineering - I will give photos of the RMS board.


 
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Offline quarks

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #779 on: May 10, 2021, 09:12:44 am »
the AC board needs its own shielding case and connector cable to the main board (see att. pic)

« Last Edit: May 10, 2021, 09:18:25 am by quarks »
 
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Offline serg-el

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #780 on: June 16, 2021, 11:17:00 am »
Interestingly enough, I discovered that the instrument has three internal temperature probes for the DCV, OHM, and AC regions (see 13.6.1 SCPI Commands). It is a nice feature of the remote commands.


One temperature sensor.
The temperature read from the multimeter is the one that was at the time of the last given internal calibration.
Since DCV, ACV and Ohm are calibrated at different times, the temperature will be different.
In the end, you can call the calibration, say DCV, separately. And when reading the temperature of the internal calibration of the DCV, this temperature will be displayed.
 
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Offline leighcorrigall

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #781 on: July 16, 2021, 01:15:20 pm »
Hello,

Is anyone who owns an Advantest/ADCMT R6581(T) interested in an original used VFD? The pins are a bit ratty and need to be realigned, but as far as I know, the display works. I replaced the display recently because it was slightly dim and it has been collecting dust on a shelf for a few months ever since.

EDIT: My VFD installation guide is available in previous posts: https://www.eevblog.com/forum/metrology/advantest-r6581-8-5-digit-dmm-mini-teardownrepair/msg3550243/#msg3550243 (display replacement is challenging to perform and you should test the display before installation)

The item is free with the exception of shipping. I accept PayPal if that works.

A picture of the display has been attached. There are also two photos that demonstrate the screen abilities compared to a Fluke 5440B in various lighting conditions.

Please PM me with a short proposal/inquiry and address. I will try and get back to you.

Thanks.
« Last Edit: July 16, 2021, 01:29:24 pm by leighcorrigall »
 

Offline dietert1

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #782 on: July 31, 2021, 05:40:42 am »
There is a minor problem with the binding post mod branadic proposed. The carrier designed for the Lowthermal 2758 binding posts requires using much longer M3 screws to mount than the original sockets. Those screws are connected to guard with their heads are close to the metal front panel connected to PE. Remaining isolation distance may be less then 1 mm. Better drill the 6 mm holes a little deeper and use shorter screws again.

Regards, Dieter
 

Offline leighcorrigall

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #783 on: August 01, 2021, 01:15:20 pm »
There is a minor problem with the binding post mod branadic proposed. The carrier designed for the Lowthermal 2758 binding posts requires using much longer M3 screws to mount than the original sockets. Those screws are connected to guard with their heads are close to the metal front panel connected to PE. Remaining isolation distance may be less then 1 mm. Better drill the 6 mm holes a little deeper and use shorter screws again.

Regards, Dieter

Thank you for pointing this out, Dieter. I measure the screw head depth to be 0.94 ± 0.05 mm (n = 12). Would this gap be a problem when working at high voltage? When I have time, I think I will put some electrical tape or a thin insulative layer between the LowThermal binding post adapter and the front panel to prevent accidental contact to ease my mind.
 

Offline dietert1

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #784 on: August 01, 2021, 03:08:16 pm »
No real problem as long as there is no short. As far as i remember 1 mm of dry is air is good for about 10 KV but electrical safety rules are more stringent. With the original sockets and their short screws the distance is about 5 mm. Apropos using the meter with higher voltages: The front end of the R6581T has a relay for that which needs exercise every now and then, just like the front/rear relay. I mean if you want to use the meter at ppm or sub-ppm levels. No different from other high resolution meters.

Regards, Dieter
« Last Edit: August 01, 2021, 06:53:55 pm by dietert1 »
 

Offline guenthert

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #785 on: August 01, 2021, 04:57:32 pm »
>  1 mm of dry is air is good for about 10 KV
I remembered 2kV, but [1] says 3kV.  I wouldn't cut it that close though and rather err on the safe side.

[1]https://hypertextbook.com/facts/2000/AliceHong.shtml
 

Offline dietert1

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #786 on: August 01, 2021, 08:53:00 pm »
Yes, about 3 KV/mm is a better number. Anyway, depending on how clean the air gap remains, electrical safety rules say 1 mm is good for 250 V (some dirt) to 400 V (clean). For 230 VAC 3 to 5 mm are recommended. These numbers no longer require rounded corners and are independent of air pressure (height).
Anyway binding posts are not completely safe, especially when used with copper lugs.
By the way the original sockets of the R6581A have a copper tube inside with a plug around it made from white metal and with the copper wiring crimped to the plugs. There is a large contact area between plug and tube, in order to reduce temperature difference and thus thermal EMF.

Regards, Dieter
 


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