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| Hacking the Victor VC-921 |
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| indman:
Hi,friends! :) On a photo buttons which I used are visible. I changed a firmware to 10000 counting, flight normal. On a photo comparing with HP-890CN when sampling about the ION of AD584-10Volt(Agilent=9.98857) and also from independent reference supply source of Uout =8.9027. On measurement of capacity - upper limit 99.99milliF. The lower limit at VC921 managed with the help of constants to be held on to 50 pF. Self-correcting of zero on capacity in a firmware at it is driven into minus if to draw out up, then nonlinearity of measurements appears. On measurement of frequency in the "Hz" mode - I decided to check an upper limit. Apparently on a photo, takes also 100 MHz, but in case of Vpp>10V from the generator without loading. |
| tronde:
Hi indman, I try to follow the Russian forum but some details are lost in translation. I can see that some of you use a separate button for Hz/Duty. What is the reason for that? Do you get access to more functions than by using a combined Hz/Duty and REL button? |
| indman:
Hi, tronde! Yes, I added 3 buttons on the front panel of a multimeter. I will explain functions of each button. "Hold/Backlight" - can add illumination of the display and holding of indications. "SELECT" - if to retain this button clicked in case of switching on of a multimeter, then the APO mode won't work, also this button has awakening function if the device entered a doze mode. "Hz/Duty" - this button allows to include measurement of frequency in the mode V ~. I think that clear I explained everything, excuse for my English! :) |
| tronde:
--- Quote from: indman on September 13, 2016, 05:17:58 pm ---"Hz/Duty" - this button allows to include measurement of frequency in the mode V ~. --- End quote --- OK, so when you use a separate Hz/Duty button you get the option of frequency in ACV. What have you changed in the EEPROM to achieve this? I have seen some images published in a zip-file by AST78512 (18.07.2016, 14:47 ) http://kazus.ru/forums/showthread.php?t=112135&page=69 so I understand that you cut some traces on the PCB, and connect the switches directly to the DTM0660 chip. I am aware of the APO disable function, but I have found that the LED for RS232 transmit will light up when the instrument is turned off by APO if RS232-function is enabled in the EEPROM. This seems to be a bug, because the LED will use almost the same current (or even more) as the instrument without the LED. Is this bug still present when you use a separate button for Hz/Duty? |
| indman:
I think that the photo of a board will explain everything. For operation of this mode it isn't necessary to do any changes in EEPROM. I connected the Hz/Duty button on contacts 31-24. The RS232 mode isn't necessary to me therefore I didn't include it. :) |
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