Products > Test Equipment

Hacking the Victor VC-921

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tronde:
Thanks, indman. This makes a lot more sense than google's understanding of the Russian language... ;D

I have tried it, and it works fine on the normal ACV function as well as the the extra ACmV function.

I am a little puzzled by this image. It's from the same zip as yours. It seems like they cut one trace? What is the reason for doing so? The translation does not make any sense to me. I have marked it with yellow.

indman:
Ok!I will try to explain. Ast78512 assigned the Hz/Duty (31-24) function only to the blue button. And it assigned the "Rel/RS232"(19-24) function to one of 4 gray additional buttons. For this purpose it is necessary to cut off the track from contact 19 which goes on the blue button, otherwise it will hinder the correct operation of all functions. :)

After updating of a firmware, technical characteristics of a multimeter look as on a photo   :D

tronde:
Thanks again, indman! This makes good sense. It is kind of challenging to grab all the finer details when I have to rely on google translate, especially when the discussion covers several different instruments as in the Russian forum.

I think I have all functions working now, except backlight which I have not tried yet. I will also try to change the RS232 protocol to Volfcraft VC840 as shown. "alvadep" also mention "PC-LINK" as an option for RS232. Is that the software for HP-890CN?

indman:
No. PC-Link-is a software for a multimeter of HoldPeak HP-90EPC. The most interesting is the fact that else none of owners of HP-890CN managed to include the RS232 mode?! Possibly, this mode is disabled in the DTM0660 processor which is set in this model. And in VC921 the RS232 mode works perfectly. :)

tronde:
If you read the documentation for HY12P66 you will see that the chip is one-time programmable to suit your needs. It is also an RS232 receive function available for programming in addition to the transmit we use. I guess it is meant for a remote controlled instrument.

It seems like Victor saved some money and re-used a chip design from a more advanced instrument.
The EEPROM for VC921 contains current modes, hFE, mV  and temperature as functions on the rotary switch as well.

Compare the hex dump shown earlier with this image from the Chinese data sheet for DTM0660.

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