Blomberg DV17600W laundry dryer MCU firmware needed. Please help!

[Sam Scarbo]

Hello,
I'm helping my brother to fix his Blomberg laundry dryer. He called a repair guy to have a look and the repair guy said the control board is faulty. They said the replacement board costs $400. Too expensive! 😨 My brother asks me to take a look. He has checked the door switch and thermal fuse, etc., and those seems fine.
After plugged to mains, there is no display. There is just a clicking sound from the buzzer, like one click per second. No other response.
I suspect the firmware inside the MCU (ATMEGA64A) got corrupted. Can someone in this forum by any chance provide the firmware (hex files for flash and eeprom) for this dryer? Much appreciated!
I have uploaded a few photos showing the control board and the MCU (an Atmel ATMEGA64A chip).

[petehall347]

is the power supply working properly ?

[redwire]

Bad FLASH memory usually doesn't repeatedly toggle a pin (buzzer) because it's an output pin and the MCU needs to boot to set that as an output. I would say very slim chance anyone here has the files, and if security bit not set.

The clicking sound could be the power supply in hiccup mode. Check the 5V rail and two 12V rails (relay power and isolated for LED?) if they are stable. Careful- the 5V, 12V rails are hazardous-live. Check D20, the electrolytic capacitors etc.

I always start by looking for fractured solder joints, use a magnifier and good light. Vibration from a clothes dryer is hard on control boards, it breaks joints and the soldering on this board for large through-hole parts looks poor. Many rings at the SMPS transformer and relay pins and the cornball jumpers.
Visual inspection I see deposits as if residual flux from a poor quality board wash at the factory. I would clean that with IPA and Q-tips. It's bad by the pushbutton SW4 and MCU pin 33 area.
2975772600 Blomberg Whirlpool Control Board

Arcelik, Arçelik now Beko. "Beko has 22 brands owned or used with a limited license (Arçelik, Beko, Whirlpool*, Grundig, Hotpoint, Arctic, Ariston*, Leisure, Indesit, Blomberg, Defy, Dawlance, Hitachi*, Voltas Beko, Singer*, ElektraBregenz, Flavel, Bauknecht, Privileg, Altus, Ignis, Polar)." *Limited to licensee in the certain jurisdiction.

[Sam Scarbo]

Hello,

petehall347, power supply is good and provides a stable 5V.

redwire, i have read out the fuse settings of the MCU. There is a "Watchdog Timer" setting that has been enabled. That repeating clicking sound is because of this.
I have cleaned the soldering flux on those areas you mentioned and some other areas that i see flux. There is no change. Still only the repeating clicking sound from the buzzer.

I have spent a good amount of time checking the surrounding components and tracing the connections to and from the MCU. I did not found any faults.

I saw a few people posted in Kijiji to sell their faulty DV17600W (this laundry dryer). They also report that the control board is not working with no display. Looks like this control board failure is a common issue with this model.

Thanks!

[stj]

if you read out the atmel, what are the fusebit settings for the protection?
i suspect you need to write your own firmware.
it could be an interesting project to replace the mcu with an arduino to get more memory and a usb interface.
then start with getting the display going - or just replace it with an lcd
then your just switching motors and heaters.

[sam_sam_sam]

if you read out the atmel, what are the fusebit settings for the protection?
i suspect you need to write your own firmware.
it could be an interesting project to replace the mcu with an arduino to get more memory and a usb interface.
then start with getting the display going - or just replace it with an lcd
then your just switching motors and heaters.

The hardest part of writing your own firmware is to get the algorithm working correctly for how long to leave the heat on and control the temperature and be consistent with out overshooting it or undershooting it the more consistent you are with it the better the performance will be and less wear and tear on heating element is going to be and the faster you will dry your clothes with this setup and weather or not to use a humidity sensor to automatically end the drying cycle if you choose to use this as feature or not

[redwire]

Some MCU's have a flash corruption or wearout problem. Microchip has deteriorated, they are basically terrible and mangled Atmel's designs. I could not find a silicon errata to see if there is a weakness there. ATMEGA64A seems to be a die-shrink of the ATMEGA64.
I would read out what you can inside the IC, look for a functioning board to read the code if the sec bit is not set.
It could have worn out its FLASH or the EEPROM or config is scrambled.
I can see "I₂S SDA SCL" and "TOUCH" on the corner of the board, it could be a (hot-live) debug port there for service techs... if the thing would boot.
Same board is used in many other makes and models so I would think they are lemons as well and Blomberg or BEKO/Arcelik needs a Class Action lawsuit over this crap.

Did the board get a new part number? For DV17600
#2975772600 in OP
#2975774704 Blomberg Dryer Electronic Board

European appliances are uncommon in Canada and Blomberg, Miele etc. does not support any "right to repair". I would never buy them again. Parts are also hard to find and expensive.

[sam_sam_sam]

European appliances are uncommon in Canada and Blomberg, Miele etc. does not support any "right to repair". I would never buy them again. Parts are also hard to find and expensive.

This “right to repair” issue is something of a sore subject for me and I think this nonsense that you have no rights for devices that you supposedly own is a bit of a joke and should not be allowed to exist in any way whatsoever

[stj]

if the flash can be read, i would test it in an emulator to see if it runs.
it could be the chip or even a brownout or zero-crossing circuit causing the resets

[petehall347]

this board looks very similar https://www.buyspares.co.uk/main-pcb...pl?pid=5289294

[Sam Scarbo]

if the flash can be read, i would test it in an emulator to see if it runs.
it could be the chip or even a brownout or zero-crossing circuit causing the resets

I don't have enough knowledge on emulator. The lock byte I got from the MCU is ":010000003FC0" and looks like the lock bit has been set, so I guess the flash/eeprom dumped out from the MCU is garbage.

[CapLeaker]

Atmega's do get corrupt after some time. I've got a stack of Atmega chipped controllers. They can run for fine for 10 years, or only last 6 months before going corrupt due to power glitches or whatever reason. Usually I end up reflashing settings and sometimes firmware and settings. I always try to read out the settings on the chip if there is a problem with the controller and either it's totally screwed up and can't even see it (the program refuses to load the read out) or I can see it but things are screwed up. Some things can really screw up in such a way you can't program it to do even if you wanted to. Resetting won't help. So far to 99% an Atmega chip can be fixed by erasing and reflashing and the controllers get hit hard, I had one instance where lightning hit the controller so hard, it fried the Atmega. They seem to be quite robust in one way, but do get scrambled brains once in a while.

The Atmega can't boot and reboot that fast in order to make that ticking sound once per second on that little buzzer. However I remember one Atmega being stuck in a boot loop. Again it was easily fixed by erasing and programming, but it was hard to do because the timing to erase and flash it had to be perfect.

[redwire]

Yeah there is evidence the AVR do erase a page or two of their flash.
Atmel old SAM7 were a lemon, unpredictable flash corruption on power-up. Most of us banned their MCU products because this cratered commercial products and was a huge fiasco- at our expense.

Worse is the Luminary Micro Stellaris LM3S ARM processors, TI bought them and they are used in expensive test equipment like Keysight 34461a, 34465a, 34470a. It's bad flash technology, it dies after even 6 months powered off. No replacement parts so Keysight had to change to a different MCU, new PCB and keep it all quiet about warranty or how they're handling it with customers that have the lemon board. TI even paid out a few % to Keysight lol. Totally screws the customers.

For AVR, Brown-out Detector (BOD) is mandatory I wonder if that bit got missed in this dryer control board firmware, or the ATMega64A is a lemon?