HCA394 Microcontroller problems

Hi Guys.
I need to start with a story. I was given a HCA394 fridge freezer that was won as a prize. Nothing wrong with that but it happens to be faulty from new. We have to forget warranty and get to the problem.

The appliance is a two door autodefrost fridge freezer: Hoover HCA 394 FKPW #340061 0329 0267. Type PF37 (info from the ENR plate).

On switch on
1. The display counts down the test sequence correctly form 9 – 0 (no err message displayed).
2. The menu selections all work OK.
3. The compressor switches off.
4. The compressor switches on after the 6 minute delay.

Problem: When the compressor cuts in it kills the display i.e it blanks out and the compressor runs forever. Basically all control is lost from the microcontroller and the compressor cannot responds.

I have replaced the microcontroller (Hoover prt # 49003068 as this contains the power supplies, triac switches etc) but the fault is exactly the same (waste of money there but I have gained a lot.) I have circuit traced the module and now have the pinning detail of the board. I discovered that the cause of the problem is an external short that is causing the -ve rail to ground out.

Can you please help me by finding out what is connected to the following PCB connectors: Con1, Con3, Con6, Con7, Push on connectors F1, F2.

Thanks guys. Edward.