Products > Test Equipment
Uni-T UT139c LCD biasing and other mods
kkontak:
My UT139C meter from work (bought in 2019) is also the new board revision with the eeprom at the back of the PCB, along with the main IC (wafer under blob).
I was able to read the 24C02 eeprom with my miniPRO, but it would not write.
The pins were:
8 V+
7 WP
6 SCL
5 SDA
4 VSS(gnd)
I resorted to desolder the eeprom and program the new BIN file directly with a SOIC8 adapter.
The changes I made were:
ADDRESS OLD -> NEW
8D 07 -> 09 (Mode1 Resistance -> Continuity)
9D 09 -> 0D (Mode2 Continuity -> Resistance)
FC 0F -> B4 (backlight 15s -> 180s)
FB 0F -> 1E (Auto Power OFF 15m -> 30m)
By default, the UT139C starts with DC on V/A modes, so I didn't need to change that, as opposed to the UT210E.
For some reason, the first 9 bytes were all FF, as per DTM0660 DataSheet. I haven't seen that at other's BINs. Even my UT210E had the first 5 bytes all FF.
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