1 Wire Communications not sure on a couple of these components

[marty]

Sorry having ISP issues trying to upload a photo.

To replace this board/UI is $270.00 and that's insane but anyways.

This is from a Kenmore Series 600 Washing machine User Interface. No idea why it just stopped working the UI panel appeared dead (3 year old machine).I tested the fuse and it was good.

Replaced the Control board (170.00 + 30 shipping). as it was completely covered in something and no access to anything other than the fuse sticking out.The new board did the same thing. I finally figured out how to access the diagnostics after a painstakingly long internet search.The UI panel completely lights up, buttons and speaker works.

Diagnostics says F6 E2 (Control board to UI panel communications error).. Troubleshooting says wire harness, it's 0.2 Ohm each wire. Could not find any trace problems either. I can only assume 1 to 3 components are dead. Tech support lol, I told them I replaced the control board and he said, well then it's not the control board and provided nothing else of value like diagnostics, led flashing on control board rapidly then 1 per second.

Right from the start this UI board has Lelon capacitors. VHZ Series.. Nice premium priced washing machine for subpar parts.

Trying to understand how the communications work here and a little puzzled by YV6AG (U13)

I believe KL1 D1 is BAT54 single schottky diode, this tested good.

ZV5wA unable to find specific chip information.

MCU is STM32 F071CBT6

Pin 21 PB10 SPI2_SCK,I2C2_SCL,USART3_TX, CECTSC_SYNC, TIM2_CH3
Pin 22 PB11 USART3_RX,TIM2_CH4, EVENTOUT, TSC_G6_I01,I2c2_SDA

So this does Single-Wire Half-Duplex communication on USART3 with tx on pin21 and rx on pin22. I assume U13 turns off or on depending on tx/rx communication?

I have yet to attach the scope as I would like to know what or how this thing works before doing so.

I drew the line for the traces on the picture along with chip codes.

Thank you.

[marty]

I have the washer working.

Desoldered the diode and soldered it back on.

Ran diagnostics left it in diagnostics mode flashing F6 E2 while I talked (5 mins or so), pressed power and it came on.

I think this issue might come back as 1-wire communications is difficult as it is on a single PCB (at least from my reading), not to mention trying to pass it over a 6 inch wire through a ferrite to a separate board.

I wondered

Did the crystals drift. (time,vibration,temp., settling)
The power was clean enough. was pretty steady 5.054 volts If I recall there was +- 300 or so microvolts change
Noise on 1-wire line.

I think it may have been a better idea to use 2-wire instead with more margin for errors.  Yes a little higher production cost a 6 inch wire and 4 pin connectors and 1 more trace all of which there was enough room for.


anyways that's my opinion, so time will tell now.