[Nick_S]

OK thanks – anyone else know please?

[Nick_S]

thanks – cant get to doing what you suggested until the weekend so will update next week

Still keen to understand how to get the machine into Debug Mode – does anyone have any ideas? – cant find this on the web so I am hoping someone knows this

[Nick_S]

I replaced all 4 relays in the bank with new ones on the power board
there is another one by itself – any idea which one it would be ?

[Nick_S]

thanks Merv – fuses triple checked and both are OK

door switches checked and jumpered but will triple check these again (on my to-do list)

Keen to understand how to get the machine into Debug Mode – any ideas?

[Nick_S]

Hi Merv – I assume they are working units as they were new and they were the correct part numbers – the power board does not seem to be supplying 240V to the Inverter so I am not sure that the inverter or the magnetron are the issue as they are downstream of the lack of 240V

[Nick_S]

Hi Merv and Dave

Thanks for your replies

I have checked the fuses and replaced them where they were blown and also the capacitor that was bulging

BUT I don’t have any voltage on the inverter supply cables

Thanks for the logic flow charts – they should be very helpful

Any ideas how I put the machine into the debug mode?

Also is there a voltage trace diagram across the power board that I could use to determine what has stopped working ?

[Nick_S]

thanks Dave – very helpful and speedy – will check tomorrow

[Nick_S]

Hi @electofix

I have just seen this same post thread from a few years ago

(https://www.ukwhitegoods.co.uk/forums/forum/public-support-forums/help-and-support/cooker-and-oven-forum/852483-bosch-hbc84e653b-combi-microwave-section-runs-for-2-seconds-before-shutting-off)

I have a similar problem with the same model, an inbuilt Bosch HBC84E653B/04 combination microwave, grill and fan oven (about 12 years old)

All functions (both the grill and fan oven) work apart from the microwave

The symptom is when you hit the start button on the microwave, it starts to count down and then stops after 3 seconds with nothing heated up.

I have checked the door safety switches and they are all OK

I have replaced the Inverter and the Magnetron with working units

I have checked the circuit board and replaced both fuses and the then the bank of relays

But the problem persists

I even found another unit on eBay and did some checks on that (also blown fuses which I replaced) and then did some major component swapping

and the problem still persists

I cannot find any information on the Initiation checks but see that failing after 3 seconds seems to be a common fault

I am in a similar situation to Paul_A in that a replacement microwave costs about £700, and a combi would be more

However that is only 1/4 of the problem as my wife wanted 4 units when they were installed 12 years ago (2 ovens, 1 combi microwave and a steamer)

Now that the combi microwave does not work and the replacement units have a different appearance – so I would have to change all 4!!! at a stupid costs if they were to look the same and all work

Do you know what else is checked in the initialisation? heat sensors etc that could be causing the microwave to fail?

thanks Nick

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