[iliffsd]

When we try to cook, the timer runs but there is no noise, no heat, nothing. The clock works and the display lights, so it's getting power. Is this simply a burned out fuse (I hope) or is the dang thing just worn out (it's 25 years old). If it's something simple, that's great. If not, I know we're way beyond time to replace her.

[magician59]

Probably not...most MW fuses are inline with the power cord. If fuse opens, you don't even get a display. You're probably not getting power past your power transformer. You need to check to see if you're getting 120VAC to the transformer. If you are, the transformer may be the problem. If you're not, the problem is the control board.

[iliffsd]

A follow-up question - how do I check that we're getting 120VAC to the transformer and is that something easy to do?
Also - if the transformer is the problem, is that as espensive repair as I think it is? If so, buying a new MW is probably best.

Originally Posted by magician59

Probably not...most MW fuses are inline with the power cord. If fuse opens, you don't even get a display. You're probably not getting power past your power transformer. You need to check to see if you're getting 120VAC to the transformer. If you are, the transformer may be the problem. If you're not, the problem is the control board.

[magician59]

Here's a breakdown of the parts. The transformer is #1 in the drawing. If you don't have any experience testing live circuits, it's best to take it to a pro. Part number: AP3118114

. To test it, just unplug the MW and pull the cover off. For safety, discharge the capacitor by shorting across its terminals. Remove the wires that go from the transformer to the magnetron side of the circuit. Protect them from wire-to-metal or wire-to-wire contace. Plug the oven back in and select a cook mode. while it's "cooking", check the primary wires at the transformer terminals for 120VAC. If there's not enough, or none at all, the problem is a bad control board. If you get the required voltage, the problem lies with one (or more) of the high voltage components.