Electronics > Metrology

Advantest R6581 8.5 digit DMM mini teardown/repair

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serg-el:

--- Quote from: leighcorrigall on April 03, 2021, 11:50:24 pm ---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.


--- End quote ---

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.

leighcorrigall:
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. EDIT: Item is no longer available.

Thanks.

dietert1:
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

leighcorrigall:

--- Quote from: dietert1 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

--- End quote ---

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.

dietert1:
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

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