Products > Test Equipment

TC1 lcr-meter transistor-tester fix

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eliocor:
Quote from: flodo on Today at 21:44:26

does someone have already dumped the original fw?

it seems to me that you have dumped a protected device, hence read data is not valid...

--- End quote ---

indman:
The Chinese original firmware ATMega324 for clones of LCR-TC1,TC6,TC7 are protected from reading of Lock by bits! Don't suffer, it won't turn out to remove them. If only who has available an electronic scalpel and the corresponding equipment for reading of the opened crystal. :)

zappenduster:
@flodo I put a multimeter (Aneng AN8008) in line. I bridged the multimeter while tc1 is in on-state. When tc1 shot down i removed the short and measured about 15uA sleep current.
Your 0.11mA Standby seem to be the 0.2mA i measured (range about 0.13 - 0.19 mA). By adding a 33k resistor to the 7805-output i got it to 15uA sleep, see my first post. But i don't know how reliable this is...


Here are some notes (which were new to me) for tc1-repairer , gathered by others:
DZ2 = TVS Diode Array  = SRV05-4 (on some pcb its silk-screened ZD2)
U5   = DC-DC controller = SD6271 Step-Up Current Mode PWM Converter. Marking ALxxx (xxx = three digit lot-number)

tc1 schematic from azure:    https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/?action=dlattach;attach=521336
tc1 schematic from indman:  https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/?action=dlattach;attach=521411

That makes it a lot easier to get a broken tc1 back on track.

Mechatrommer:
i bought this TC1 unit with expectation it is the same as M328 variant that i bought and worked charmingly earlier, but now my brother is using it now so i have to buy for myself. it turn out this is different atMega324 with STC15W104 chip, this turn out to be nightmare. and then i found this thread. after back and forth reading this thread i managed to get something from STC-ISP...

--- Quote ---Checking target MCU ...
  MCU type: STC15W104
  F/W version: 7.2.5T

Current H/W Option:
  . Current system clock source is internal IRC oscillator
  . IRC frequency: 32.975MHz
  . Wakeup Timer frequency: 36.825KHz
  . Do not detect the level of P3.2 and P3.3 next download
  . Power-on reset, use the extra power-on delay
  . RESET pin behaves as I/O pin
  . Reset while detect a Low-Voltage
  . Thresh voltage level of the built-in LVD : 2.66 V
  . Inhibit EEPROM operation under Low-Voltage
  . CPU-Core supply level : 3.74 V
  . Hardware do not enable Watch-Dog-Timer
  . Watch-Dog-Timer pre-scalar : 256
  . Watch-Dog-Timer stop count in idle mode
  . Program can modify the Watch-Dog-Timer scalar
  . Do not erase user EEPROM area at next download
  . Do not control 485 at next download
  . Do not check user password next download
  . TXD is independent IO
  . TXD pin as quasi-bidirectional mode after reset
  . P3.3 output HIGH level after reset
  . Testing time: 2017-9-22

  . MCU type: STC15W104
  F/W version: 7.2.5T


  Complete !(2018-10-08 01:17:05)

--- End quote ---
if i choose STC15L104W as demonstrated by earlier experimenters, i wont get any report from the chip.

the problem when i got this unit is the shorted C11, so i changed with 100nF, no more short, but when battery is applied, lcd turn on white for half a second or so and then random garbage before turned off immediately. pressing start button do nothing. sometime the tester did turned on and firmware on mega324 did start, but its just luck. after reprogramming STC15W104 with frodo's tc1_u4_v0.3.1.hex, now its totally blank. removing and applying battery, there is no more white screen, no start button respond nothing. ah F the STC chip what was that? support us people of China guaranteed powerful home grown business FU so much so for anti disturbance super strong chip.

earlier i removed the STC chip and connect Vbat pin to the next pin controlling the boost dcdc chip (AL673 marking), the atmega did start but halted at welcome screen its like waiting for signal on either P3.3/PD2 or P3.2/PD1 i suspect to start measurement. i have to experiment later. i think i will remove the STC chip and glue it to blank space on the pcb so it can wave dick all day long all its like. i need to find a way to start the atmega chip the hard way. or anybody else can help me make program for the STC15W104 chip? i will be gratefull, for now i dont have time to play/install with Keil or whatever. i just want it to work and then move on.

btw,
1st picture: thermal imaging superimposed when shorted C11 is installed. the SD6271 got hot 73degC as registered by my camera.
2nd picture: how i connect the STC15W104 to USB-UART converter. need few experiment though since warning from people to use 3.3V rail, 5V may damage the fucked up super strong STC. it turned out i just use 5V UART and it just worked fine.
3rd picture: the fucked up super strong anti disturbance STC15W104 chip made home grown in China, please support it people of China. i really pissed off can you imagine by now?

thanks to people directly or indirectly contributed to this thread esp OP zappenduster, frodo and others, but your FW doesnt work with mine :'( and schematics providers indman and azure.
edit: added 4th picture with its IO state to PD1/PD2 from my crude test.. and the mega fw wont start by simply toggling PD1 pin, so there must be the right sequence to turn it on |O

prakash_kadri:
  @zappenduster, I had same issue with my T7. Replaced  C11 and C12 with 100nF 100V and 4.7uF 100V. Now it is working. Thank you very much for sharing the fix.  :)

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