T7 Tester

[slybunda]

Ordered this T7 tester from aliexpress and it arrived today. Working great so cant argue for the price of £10 inc post.
Iv took some pics of the insides incase people are interested in how it runs. The main chip is unmarked. 300mah battery which uses jst xh connector and silicone wires which i think are either 22awg or 24awg.
Firmware version it runs is 3.12k
Good addition to my toolkit, surprised i went without this for so long.
Anything i should be careful of or to lookout for when using this? Making sure caps are discharged prior to testing is all i know really.

[bffargo]

See the primary 360 page thread regarding these testers: https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/9000/

[madires]

The MCU is most likely an LGT8F328. It's possible that your tester lacks the self-adjument feature. And some measurements are sub-par because of the different MCU and a poorly adapted firmware.

[evmillan]

Please could you provide a link to a product that is well implemented and built with the recommended components?

It is difficult to find the proper one when searches turn up over 50 products with similar features in AliExpress

[madires]

Unfortunately I can't. It's a lottery at the moment. The best bet is to look for a tester with DIP ATmega328 or to build a Transistortester yourself.

[slybunda]

The MCU is most likely an LGT8F328. It's possible that your tester lacks the self-adjument feature. And some measurements are sub-par because of the different MCU and a poorly adapted firmware.

Not sure how to test its accuracy other than with some known resistors and caps i have that did test good and in spec.
If i jump pins 1, 2 and 3 the tester goes into calibration mode and then at the end displays firmware version which is 3.12k.
Is that the mode you are referring to?
Pic attached

[slybunda]

Please could you provide a link to a product that is well implemented and built with the recommended components?

It is difficult to find the proper one when searches turn up over 50 products with similar features in AliExpress

At this point in time i assumed all testers use fake or clone chips so i just went with the cheapest one.

[madires]

Not sure how to test its accuracy other than with some known resistors and caps i have that did test good and in spec.
If i jump pins 1, 2 and 3 the tester goes into calibration mode and then at the end displays firmware version which is 3.12k.
Is that the mode you are referring to?

One of the effected measurements is ESR. And yes, that's the self-adjustment feature.

[slybunda]

Not sure how to test its accuracy other than with some known resistors and caps i have that did test good and in spec.
If i jump pins 1, 2 and 3 the tester goes into calibration mode and then at the end displays firmware version which is 3.12k.
Is that the mode you are referring to?

One of the effected measurements is ESR. And yes, that's the self-adjustment feature.

Think i missed the pic in the other post is this the self test you mean, pic attached

[slybunda]

Anyone know if this has a charge controller chip in it? I was expecting a tp4056 but dont see one. Does it just give 5v charging voltage to the battery and rely on the batterys protection board to prevent overcharging?

[madires]

Yes, it has a charge controller.

[slybunda]

Whats the name of the controller this uses?

[madires]

TP4057

[slybunda]

Where abouts is it on the board? Im gonna have to get a microscope my eyes are too old now  :'(

[Serg65536]

As far as I know, it's possible to swap the chip to atmega328 with minor changes and enjoy the fool glory of the original open source tester.
But that's not a trivial task.

[madires]

Where abouts is it on the board? Im gonna have to get a microscope my eyes are too old now  :'(

Should be U12, near the duo LED.

[slybunda]

Thanks for that will try and get better photo of u12.
Not sure why id want to change the chip to an atmega328 just yet since its working fine and seems to be doing its job. Tested more new resistors today and all resdings are very accurate.
Very handy having this I should have bought it years ago

[slybunda]

Got some details on U12. Its marked 17R which is possibly a 9017R, sot-23-6 , 6 pin constant current constant voltage charger.

[madires]

So they changed the charger chip. There are so many different variants of the TC1 and family it's hard to track them all. BTW, normal resistance measurements shouldn't be impacted by the alternative MCUs as it's just a simple voltage divider setup.

[coromonadalix]

since the firmwares codes are out

many take this and sell out many variants, some follow the "design"  and other not, cutting functionality over pricing etc ... and have other mcu variants

[slybunda]

Yep this looks like a simple device on the inside, could probably build one on a breadboard for little cost.

What sort of tests should i do on my one to see if its lacking any functionality?

[madires]

The functionality of the tester clones with a modified firmware is limited anyway (compared to the original OSHW firmwares). For the fancy display output they have to drop features because of the small flash size.

[slybunda]

As far as I know, it's possible to swap the chip to atmega328 with minor changes and enjoy the fool glory of the original open source tester.
But that's not a trivial task.

you know, now thinking about this that atmega328 chip im sure i have that on an arduino uno r3 i have lying around somewhere. maybe that can be adapted to do the job?

[NF6X]

I just got an "AITRIP" brand T7 tester from Amazon. Mine has an APT32F172K8T6 microcontroller. You know you're getting the good stuff when they use a genuine TFXTDOL brand ZIF socket. 

[NF6X]

When I short 1-2-3 to enter the self-test mode, it identifies itself as "FNIRSI-TC1". It does not display a version number at the end of the test.