I am trying to repair a tumble dryer board that is producing no DC voltage to the micro. The mains voltage is about 240AC (UK). I have found two resistors at the power input stage that are clearly sick (one burned and open circuit, the other measuring about 2 ohms). They are R1 & R2 in the attached schematic. The schematic is just the input stage that I’ve been able to work out so far, with lots of tracks hidden under components. I’m pretty sure R1 is 62 ohms although it’s burned and the colours are not 100% clear. R2 is brown, black, violet (I think), silver, so 100M. Before I change both and fire it up, and as I’m out of my depth with this design of power stage, I have a couple of questions:
1. Are the values 62R and 100M plausible for R1 & R2?
2. Is it likely that one or other of these resistors is the root cause of the problem? There are no other signs of stress on other components and the diodes all measure OK.
3. Are there any other specific things I should measure?
Thanks!