Our dishwasher (A Siemens SD6P1S) didn’t react when pushing the switch on button. No beep, no light on the control panel, nothing… The pleasure of manual dishwashing announced itself silently…
Before doing anything to it, I made sure to check if the circuit breaker hadn’t tripped and that there was power available on the power socket. This being the case and the machine appearing to be powerless, the first potential causes of failure which came to mind were maybe a bad contact in the power switch or maybe some internal protection which had tripped ( I knew from a previous repair that the machine has a float at the bottom to detect leaks.) or maybe some door contact malfunction.
Troubleshooting
When opening the machine I first tried bypassing the power switch but the machine still didn’t react. I also assessed that the door contact didn’t really function like a general ‘shutoff’ and it seemed to be working fine so this probably wouldn’t be the problem. I also didn’t see any water at the bottom of the machine, so no leaks. I tried the float switch but the machine didn’t react. Having checked the most obvious potential causes I was starting to suspect that there might be a problem in the internal power supply of the machine…
I could find only one box at the bottom of the machine from which all the wire harnesses started. Also the power cord was connected to this box. This box seemed to contain the power supply and the control unit.
Demounting the box and opening it was difficult but I managed in the end. I pulled out all the plugs of the wire harnesses (Making pictures before to make sure I would be able to install them back in the correct position!) and removed the PCB from the box.
When I removed the PCB, I noticed that a small black rocky speck remained in the box. This seemed strange…
When studying the print it became clear where the black speck originated from: One of the IC’s was missing a chunk. Was I lucky and was the trouble shooting going to be this quick?
When putting the black speck back in its place I could determine that the part in question is a TNY264GN. It is a switcher IC which protects the machine against, among others, under and over voltages and short circuits. When searching the web, it became clear that this part often gets damaged on various appliances across various brands. I even came across a dedicated website which explains in detail how to replace this component: https://www.maakmijnwitgoed.nl/content/7-stappenplan-zelf-lnk304-weerstand-vervangen
Repair
I ordered 2 new IC’s (to have a spare). While waiting for their delivery I checked the maintenance and repair history of the machine and noticed that the last time I had cleaned the labyrinth was about 41 months ago. My statistics showed that the chances of a blocked labyrinth in the nearby future were very high. Having the machine open and not functioning anyhow, I decided to clean the labyrinth pre-emptively. Please check my other post on how to clean the machine’s labyrinth.
When I received the new IC, I stared with its replacement.
When desoldering the IC I unfortunately damaged/removed one of the soldering pads of the pcb. So when I soldered the new IC in place I soldered a small wire on the 3rd pin to connect it to the ground of the pcb.
Afterwards I installed the print back in the box and connected everything and let the machine complete a full program to properly test it. Once the machine completed the program I assembled it completely and put it back in its place. Problem fixed 🙂
