GMC305PDS07 - Whirlpool Microwave Not Heating

[spidercharm]

Hi All, 

Whirlpool microwave / oven combo - cabinet mounted.

Few weeks ago, microwave stopped heating. Display, timer, lights, turntable etc. works fine. 

I have seen several videos, studied the circuit diagram carefully and did troubleshooting for all the parts - switches, diode, capacitor, magnetron, fuse etc. and they all seem to be okay.

1) HV Transformer (when removed) is testing fine on it own. Less than 1 ohm across the terminals and no shorting with the body. No visual signs of problems or smell. 

2) HV Transformer (terminals removed from transformer), I can see 120v coming in primary input terminals. I think this means circuit board and switches are fine. 

3) When HV transformer is connected, I don't see 120 v input coming in to terminals. This might mean transformer is shorted (based on 2 above). However, I am not sure if this can be caused by something else (because transformer is testing fine on its own as I mentioned above). 

I have spent 2-3 weeks on it and would greatly appreciate your help. 

HV Transformer is about 200$, so wanted to make sure I am not missing anything before ordering replacement. 

Thanks in advance.

[LearningTech]

Yes power to HVT  means controls are good. Unless its  changes under load.

if the HVT is shorted on primary winding it would blow fuse.

WHAT is the AMP draw of the HVT when all installed?

0 and it passed continuity test then. You have control side issue

On 10/2/2018 at 6:44 AM, spidercharm said:

, I don't see 120 v input coming in to terminals.

His is control side issue. Power should get there whether or not the transformer is connected

 check door switches filter board fuses, and TCOs, if all good id suspect the main control. 

On microwaves always separate into 2 areas control and HV. 

If there is no power to HVT (when connected) then no need to think of HVT mag cap or diode, (unless its blowing fuse) at least not until you get power to the HVT