T7 Tester - Page 1
Forum section: electronics / testgear

author: slybunda
author_rank: Regular Contributor
timestamp: January 12, 2024, 06:04:00 pm
content: 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 3.12kGood 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.

author: bffargo
author_rank: Regular Contributor
timestamp: January 12, 2024, 06:07:46 pm
content: See the primary 360 page thread regarding these testers:https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/9000/

author: madires
author_rank: Super Contributor
timestamp: January 12, 2024, 06:14:51 pm
content: 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.

author: evmillan
author_rank: Newbie
timestamp: January 12, 2024, 06:57:01 pm
content: 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

author: madires
author_rank: Super Contributor
timestamp: January 12, 2024, 07:10:21 pm
content: 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.

author: slybunda
author_rank: Regular Contributor
timestamp: January 12, 2024, 08:18:43 pm
content: Quote from: madires on January 12, 2024, 06:14:51 pmNot 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

author: slybunda
author_rank: Regular Contributor
timestamp: January 12, 2024, 08:20:07 pm
content: Quote from: evmillan on January 12, 2024, 06:57:01 pmAt this point in time i assumed all testers use fake or clone chips so i just went with the cheapest one.

author: madires
author_rank: Super Contributor
timestamp: January 12, 2024, 08:32:15 pm
content: Quote from: slybunda on January 12, 2024, 08:18:43 pmOne of the effected measurements is ESR. And yes, that's the self-adjustment feature.

author: slybunda
author_rank: Regular Contributor
timestamp: January 12, 2024, 08:35:55 pm
content: Quote from: madires on January 12, 2024, 08:32:15 pmThink i missed the pic in the other post is this the self test you mean, pic attached

author: slybunda
author_rank: Regular Contributor
timestamp: January 12, 2024, 11:57:06 pm
content: 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?

author: madires
author_rank: Super Contributor
timestamp: January 13, 2024, 09:59:49 am
content: Yes, it has a charge controller.

author: slybunda
author_rank: Regular Contributor
timestamp: January 13, 2024, 12:35:11 pm
content: Whats the name of the controller this uses?

author: madires
author_rank: Super Contributor
timestamp: January 13, 2024, 01:17:19 pm
content: TP4057

author: slybunda
author_rank: Regular Contributor
timestamp: January 13, 2024, 01:32:36 pm
content: Where abouts is it on the board? Im gonna have to get a microscope my eyes are too old now :'(

author: Serg65536
author_rank: Regular Contributor
timestamp: January 13, 2024, 01:40:55 pm
content: 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.

author: madires
author_rank: Super Contributor
timestamp: January 13, 2024, 02:51:14 pm
content: Quote from: slybunda on January 13, 2024, 01:32:36 pmShould be U12, near the duo LED.

author: slybunda
author_rank: Regular Contributor
timestamp: January 13, 2024, 03:22:49 pm
content: 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

author: slybunda
author_rank: Regular Contributor
timestamp: January 13, 2024, 03:28:23 pm
content: Got some details on U12. Its marked 17R which is possibly a 9017R, sot-23-6 , 6 pin constant current constant voltage charger.

author: madires
author_rank: Super Contributor
timestamp: January 13, 2024, 03:45:34 pm
content: 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.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 13, 2024, 03:52:33 pm
content: since the firmwares codes are outmany take this and sell out many variants, some follow the "design" and other not, cutting functionality over pricing etc ... and have other mcu variants

author: slybunda
author_rank: Regular Contributor
timestamp: January 13, 2024, 04:17:49 pm
content: 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?

author: madires
author_rank: Super Contributor
timestamp: January 13, 2024, 06:29:14 pm
content: 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.

author: slybunda
author_rank: Regular Contributor
timestamp: January 13, 2024, 07:52:11 pm
content: Quote from: Serg65536 on January 13, 2024, 01:40:55 pmyou 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?

author: NF6X
author_rank: Unknown
timestamp: January 21, 2024, 08:44:58 pm
content: 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.

author: NF6X
author_rank: Unknown
timestamp: January 21, 2024, 09:18:07 pm
content: 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.

author: slybunda
author_rank: Regular Contributor
timestamp: January 22, 2024, 02:48:20 pm
content: Quote from: NF6X on January 21, 2024, 08:44:58 pmwhy does your T7 not have the crystal oscillator that my one does? this is odd.

author: NF6X
author_rank: Unknown
timestamp: January 22, 2024, 02:53:18 pm
content: Good observation. I didn't notice that. I speculate that the microcontroller has an internal RC oscillator. I wonder how much that affects the measurement accuracy? I didn't get this expecting to make accurate measurements; I mostly wanted it to answer questions like "is this (still) a transistor". But if it's less accurate due to not using a crystal timebase, that might be a problem for folks who don't already have lots of other test equipment.

author: SAIT_Tim
author_rank: Newbie
timestamp: January 30, 2024, 04:11:23 pm
content: Quote from: NF6X on January 21, 2024, 09:18:07 pmI've recently acquired the same tester I suspect as it identifies itself the same way despite saying T7 on the front.I thought it was going pretty well until I measured a couple of new BT136-600B Triacs (Farnell sourced). It identified them as Triacs but displayed the pinout completely wrong...Can anyone else verify this, and whether other variants of the tester do the same?Cheers

author: slybunda
author_rank: Regular Contributor
timestamp: January 30, 2024, 10:42:40 pm
content: Thats interesting, iv not got any triacs at hand to check with. What version firmware has your T7 got? Do you have a pic of its insides?

author: SAIT_Tim
author_rank: Newbie
timestamp: January 31, 2024, 10:20:50 am
content: Quote from: slybunda on January 30, 2024, 10:42:40 pmI purchesed it a few weeks ago from WAVGAT store on Ali but otherwise its unbranded.It looks to be identical to yours in every way - same MCU marking, same board revision and layout, and same FNIRSI-TC1 message when you self test, without a firmware revision number when it completes.I did some further investigation:If you attach Triac with MT1 > Pin1, MT2 > Pin2, G > Pin3, it reports on screen with MT1 and Gate transposed.If you attach Triac with MT1 > Pin1, MT2 > Pin3, G > Pin2, it reports the pin out correctly.Some other connection combinations display correctly and some don't...Maybe FNIRSI will fix the firmwareOh, and these Triacs are BT136-600E, not B as previously mentioned.

author: madires
author_rank: Super Contributor
timestamp: January 31, 2024, 11:58:54 am
content: I've checked a BT136-600 (standard, not E for sensitive gate) with an original TC1. The TC1 got the gate correct but confused the main terminals. This is to be expected as the TC1's firmware is based on the k-firmware. The m-firmware has an additional cross-check to figure out the main terminals. What surprises me is that your T7 even messes up the gate. Don't wait for a new firmware from any Chinese clone manufacturer. They all take the OSHW firmwares, modify them, but never publish any code.

author: NF6X
author_rank: Unknown
timestamp: January 31, 2024, 03:10:50 pm
content: My T7 is just an appetizer. The main course will be my own hardware variant, running your delicious firmware.

author: slybunda
author_rank: Regular Contributor
timestamp: January 31, 2024, 07:47:30 pm
content: Odd why does my one show the firmware version after it self calibrates and your one doesnt if both have same hardware inside?

author: SAIT_Tim
author_rank: Newbie
timestamp: February 01, 2024, 09:03:26 am
content: Quote from: NF6X on January 21, 2024, 08:44:58 pmSorry if I confused everyone, my T7 is exactly the same as this one and doesn't show FW version.

author: slybunda
author_rank: Regular Contributor
timestamp: February 01, 2024, 11:17:06 am
content: ahh, that one is named T7 but its different from my one internally. its odd since i believed all of these devices were identical and manufactured by one specific company and then just rebadged for different resellers.turns out there is some hardware difference in them too so maybe they are made by different companies or maybe different revisions?

author: madires
author_rank: Super Contributor
timestamp: February 01, 2024, 12:56:37 pm
content: There are about 10 variants of the TC1/TC2/T7/T7H.

author: slybunda
author_rank: Regular Contributor
timestamp: February 14, 2024, 10:49:41 am
content: Modded the test leads that came with the tester, it had short ones but biggest issue was lack of flexibility. 24awg pvc wires it comes with stock, desoldered the connection at the hook clips and crimped on new dupont connectors to some silicone 22awg wires now its far easier to use thanks to wire flexibility.