I’ve spent nearly 30 hours taking this unit apart, measuring key H.V. components (diode, magnetron, capacitor), door switches, thermostats, and flame sensors.
Checked for loose wiring/connectors, bad fuses, and broken wires inside their PVC or cloth insulation jackets.
Performed Key Panel, Smart Board, and Sensor tests; but I still cannot locate the reason(s) why it’s not heating. Both the H.V. cap and diode have been replaced even though the originals tested out ok.
Utility supply was measured at 119.3VAC
The H.V. tranny tested out with the following results:
Primary winding: .4Ω
Secondary winding: 68.5Ω (schematic shows nominal as 79Ω) This was measured from the white wire on the tranny to ground.
Filament winding: 0Ω
Primary winding to ground: Infinite
Filament winding to ground: Infinite
The Magnetron tested out with the following results:
Resistance between the two filament terminals: .1Ω
Resistance from filament to Magnetron chassis: Infinite
Now, I don’t have a meter that will accurately measure resistance (milli-ohms) in the windings; but the schematic lists them as 430mΩ on the primary and 100mΩ on one of the secondary legs.
Anyone have some ideas??? I’m completely stumped on this one.
You can check those 4000 series diodes with
just about anything. You need a meter that’s running
at least a 9 volt battery to get anything out those HV diodes.
It’s probably a Simpson 260, just hope that one didn’t walk
[SIZE=3]away from you. A new one is about 250 -300 bucks. [/SIZE]
[SIZE=3]You would be able to check the HV diodes with that one.[/SIZE]
[SIZE=3]you would just need to set it on R times 10,000.[/SIZE]
If you locate it -hang on to it. I still have mine
and I still use it quite a bit.
Ok… provided everything is wired correctly and you are
getting 120VAC at the primary of the transformer, about
the only two things left would be 1. the transformer
is not putting out HV (bad secondary) or 2. the mag is bad.
Based on youre earlier post I suspect the latter of the two.
— End quote
Yup. That’s why I’ve been trying to find it (Simpson).
If not, I could whip up a 15v HV diode analyzer early next week with my variac and a couple of other component parts.
But, seeing as how I’ve already got the mag, I may as well just install it (and reuse the t-stat on the original). The worst that could happen is that it still won’t heat.
It may actually be the HV tranny since there’s not really a loud noise coming from it. It has that ‘bad transformer hum’ sound during operation. But, the mag is the most likely candidate.
Mother’s day tomorrow, so I won’t get around to it until Monday at this point. I’ll let you know after I change out the mag.
Electronics that use KV are more of an intimidation factor than anything else.
You just need to be smart about things, make a checklist, double check your discharged caps, stay systematic. . . .and curse a little bit now and then.
The rewards of the accomplishment itself, and saving hundreds of dollars in the process, are well worth the time and effort when a resolution has finally been achieved.
