EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: VeryFastSnail on December 15, 2019, 01:15:03 pm
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Hello everyone. First of all let me apologize for this question, but I figured out that EE community might help... :)
Long story short: I had this accident with my quick 861dw hot air soldering station, I was powering it down while it was ramping up the air pump , and after next power up it started, but it took 6-7 seconds more, buttons are responsive but I have to hold them longer and the whole air station works slower (maybe half as slow as normally), I mean every function, including powering up, to controlling heat and air speed, buttons matrix and other functions. even beeper that beeps when it boots, beeps for longer. How could I fix this problem? P.S station works as intended, but everything is so slow, its like delay(250) function was placed in loop()... PCB look perfect, no damage or nothing, MCU itself look fine. No caps are shorted around it.
MCU atmega16A
Have direct access to SPI via connector, but I can't connect to it either 0x0000000 err is dropped or 0xfffffff
What I have already thought of:
- Replace MCU (where to get firmware, maybe extract it from current one while it still alive)
Maybe there is issue with chip clock? Atmega runs on 16 mhz right? Maybe there is any way that it got slower? maybe 8mhz? that would explain slower performance..
- Extract firmware somehow from it... There is connection of 7 pins on the board that is connected to MOSI MISO SCK AND RESET, then two pins for +5v and gnd, but I wonder if that chip is locked... if not replace mcu and flash old firmware.
- I saw zener diode that has very low resistance across it 2ohms, but it's connected to temperature sensor or something so maybe its normal? :?
there are external oscillator place, but internal fuses needs to be programmed...
Maybe there is external pin of clock that I could sample with my oscilloscope
What do you think?