Would it be possible to mod my multimeter?

[GBember]

Hi! I have a Minipa ET-1507B (Brazilian brand) and it seems to be just a rebrand of a Mustool MT108T, except it's missing the thermocouple temperature reading function.
I wanted to ask if it would be possible to enable that on my meter?
The chip is a black blob, so if it's a firmware change there's no way of doing anything I guess
Board pictures of the Minipa






pictures of the Mustool can be found here https://budgetlightforum.com/t/test-review-of-dmm-mustool-mt108t/55157

Thanks in advance!

Edit: I forgot to mention, when I turn on the meter, all segments of the LCD light up briefly and I can see symbols related to temperature reading

[moffy]

It is most likely the chip that varies, as when the selector switch is in the correct position, it would need to have the 'TEMP' function programmed into it to be selected. After a brief look at both PCBs I couldn't see any differences apart from some writing and maybe LED33V.

[GBember]

I think there's a resistor missing on the Mustool on the right side of the main chip, but it's not a 0 ohm so I doubt it's some configuration resistor and an extra LED labeled led3v or something like that, but it's probably nothing. Sadly you're most likely correct.
Thanks for the help!

[Gyro]

Possibly not something that exactly matches your wishes, but I would suggest that you look for a TM-902C thermocouple thermometer. They are very low cost and I would be surprised if they are not available anywhere in the world. A couple of potential advantages: firstly you will probably get better initial accuracy (even if possible to modify your multimeter, you would probably need select-on-test resistor(s) for adjustment, involving multiple disassembly). Secondly, you get to use your multimeter for measurements and monitor temperature at the same time.

You will probably find the TM-902C not that much more expensive than buying just a thermocouple probe.


P.S. If you go in this direction, get one with a simple slide on/off switch rather than a push-on button. Battery life will be considerably better.

[GBember]

Thanks for the advice! I already got one of those on my way from china, I wanted to do this on my meter just for fun. I wish I knew about that thing with the slide switch and the battery life before ordering mine...

[mwb1100]

Too late since you have already ordered, but another alternative would be to get something like an Aneng AN8002/Zoyi ZT102 for about $15 or AN8009/ZT111 for a couple bucks more.  Then you have a second meter as a spare.  Also would let you monitor current with one meter while having another for voltage (or whatever) measurement.

[mikerj]

I think there's a resistor missing on the Mustool on the right side of the main chip, but it's not a 0 ohm so I doubt it's some configuration resistor and an extra LED labeled led3v or something like that, but it's probably nothing. Sadly you're most likely correct.
Thanks for the help!

The Aneng M20 is another clone of this DMM and has the resistor in place and does NOT have the temperature function, just like the OPs.  Could be worth removing it just to see what happens.

[GBember]

I don't have a hot air station yet, which would make things a whole lot easier for this kind of job. I'm looking to get one, so I might try this in the future.
Thanks for finding this other model and board pictures!