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LCR T7 tester problem

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    Re: LCR T7 tester problem

    replace the stc with the circuit i posted and re-flash the atmel with the software from madires at that link
    if you cant build the atmel software then i can create it for you.
    do you have tools to program AVR chips?

    btw, some people say to re-flash the stc chip,
    i tried that for a friend but the stc chips are shit and dont always go into standby - result is it drains the battery overnight!

    these testers (T1 / T7) have a couple of known problems.
    one is the stc chip fucking up, another is a couple of ceramic caps shorting in the boost circuit for the zener testing.


      Re: LCR T7 tester problem

      1. Getting ready to flash the U4 power controller. We solder the USB-UART converter with a stabilizer to the board.
      (3.3V to 3.3V, Gnd to Gnd, Tx to P1, Rx to P2).
      2. We connect the converter, wait for it to be detected by the system, launch the software, select the com-port, select the firmware from the archive (p. 1), set the frequency to 12 MHz, apply power, the processor starts, does not go into boot mode, is not detected by the programmer .
      3. Experimenting with the sequence of power supply to the processor and pressing the "Check MCU" & "Download/Program" buttons.
      4. We study the datasheet on U4, we find that the Test button of the tester is connected to the Reset output. Click "Check MCU", click the Test button, the microcontroller resets and is detected. In the same way, we launch the firmware, and finally, we flash U4.
      Attached Files


        Re: LCR T7 tester problem

        yes, but we are flashing firmware for the new atmel code,
        i dont think it works with the original chinese code - not on T1 anyway.


          Re: LCR T7 tester problem

          Originally posted by stj View Post
          do you have tools to program AVR chips?
          Can that be done with an Arduino Uno?


            Re: LCR T7 tester problem

            yes, atleast i'v seen people doing it.

            personally i just use a USBasp programmer - why not when they cost about $2!!
            saves a lot of messing around with patch wires and INO files.


              Re: LCR T7 tester problem

              Don't have one but I'll see if I can find one in town


                Re: LCR T7 tester problem

                Hi all.

                Feel I should update the situation...

                Stj's original suggestion regarding upgrading the crystal whilst installing two resistors and reflashing the Atmel was surely advice which I should have followed, however...

                Considering that the flashing kit was almost the same price as the 'latest' TC2 ESR tester, I took the lazy route and just before Xmas received the TC2.
                There are already three dead variations of the MK328 component tester in my 'to fix' bin, so I was ├╝ber careful measuring caps with this one.

                After less than three weeks, whilst testing germanium diodes and transistors in an old radio, the TC2 just switched off. I didn't think much of it, as it had been doing that since it had arrived.

                But that is the state it is still in to this day!

                I have had a quick peek and found two dead zeners, and shall open up a new thread about this tester in the near future, with more detailed photos and explanation.
                To be honest, it is a pretty crap tester, but that's another story too.

                Thought it was a bit rude to not have given an ending to this thread..

                Attached Files


                  Re: LCR T7 tester problem

                  saves a lot of messing around with patch wires...

                  Just interesting... stj

                  I have also a simmilar LCR-T5 the red one with two button, and... acidently testing a charged cap... offcorse
                  The tester at this point shows wiered things, mostly like mosfets or so... it boots up normaly... so, I thinking, maybe is burned some input thingy inside uC but maybe lucky enough to extract firmware from it? I realy like it original chinese firmware.

                  Question is, can I read and write atmega328 with ch341a programmer throu spi header, and what prearrangement have to be done before that?
                  I do not any experiance about that, so please explain step by step
                  Can be done in circuit somehow?
                  Attached Files
                  Last edited by harp; 03-04-2023, 07:59 PM.


                    Re: LCR T7 tester problem

                    that looks like the old "fish" tester i think - very early design style.
                    firstly, if it's not dead check if it has the input protection diode-pack.
                    if it does then remove it and try again.
                    Attached Files


                      Re: LCR T7 tester problem

                      I dont see any protection diode pack...
                      Attached Files


                        Re: LCR T7 tester problem

                        under the board?


                          Re: LCR T7 tester problem

                          No, on back side there is no any component.
                          This 6-leg smd package nor multiple diodes is not on the pcb.
                          I look even under zif socket.
                          Last edited by harp; 03-05-2023, 04:01 PM.


                            Re: LCR T7 tester problem

                            then check the 6 resistors on the sensing likes, if they are good your atmel is damaged.
                            on the bright side - it has a programming header.


                              Re: LCR T7 tester problem

                              Check R1 till R6 in circuit, all is still ok... 680R and 470K
                              Check for shorts and nothing find.
                              Input pins 1, 2 and 3 from zif socket are also directly connected to atmega328 pin #23, #24 and #25.

                              So, can I try to read this chip with CH341A, is connection direct or crossover some pin... what power... what is next step?


                                Re: LCR T7 tester problem

                                i have never used a ch341 to read the spi bus, so i dont know.
                                99% chance they set the lock bits though, or the firmware would be online somewhere.
                                unless it's here: