Amana HDC18 Microwave

[royc]

And btw, do something about your long location line, I hate scrolling across to read posts..lol

My old eyes are not what they used to be,,I still use 800X600..lol

Roy

[wolfman32]

I have unpluged the HV transformer and turned it and it will not blow a fuse. The HV trans. hums very loud. but nothing seems to be grounded. I have new spare parts and I have switched everything out but the mags. I guess I will try them but they check to be good. I have a book on this unit and I have tested everthing like the book says and everthing tests good.

[markwolf]

My vote is for an internally fused(melted/shorted)power diode at the capacitor.
Most standard meters will not have enough power to activate the diode to test it.
If you are going to be working on microwaves you will want a meter to test large power diodes.It is a common problem.

[leonmiller]

Remove the secondary leads from the transformer and try it again. If you have a megger, Amana recommends megging transformer first - if not, fire it up with secondary isolated. If it blows fuse, replace transformer. If you need parts help, post or email me. We are an Amama Commercial Service Depot. HDC-18's pretty bullet proof, don't see many any more - don't have manuals here at home, but can provide more assistance tomorrow when at office.

[leonmiller]

Got to my book, remove wires 4 thru 8 on transformer to open secondary and both filament circuits. Wire 4 is the HV wire, stay away when powered up!
If it still blows fuse replace transformer, give me your mfg. number off the serial plate and I'll give you a part number. - Good luck

[ndfrozen]

I have one that is blowing fuses only when you try to cook. When you push a button to cook it will blow the fuse I have checked all I know. I am new to microwaves so any help would be GREAT!!

You can isolate this unit in half, take off the triac
gate wire, its the single wire across from the pair of double wires on the triac. if it doesn't blow when you put in load, close door, and press number1, then problem is in mag. side of unit. if it blows problem in control side of unit.

If mag side -then check big transformer visually for burned up hv coil ( what i see the most, since drawing hi amps this is the main suspect, nothing else in this unit can handle that many amps more that a second or so), next is to visually check the mags at there hv connections, usually the white terminal shroud is burnt up or has a brown-blister on it. A dead give away that it is shot. next comes the caps - usually find grease or debris shorting out the terminals, then diodes for shorts to ground.
these are all visual checks, you can also use your meter to check them out, go to amana TS manual it will tell you how to, also get with amana's tech support pretty good folks.
to isolate mags you have to remove hv wire jumper from caps, leaving the hv wire on one cap. Run unit with small glass of COLD water if it heats up that mag circuit is good. next, move hv wire to other cap and do test.
NOTE: if hv transformer is bad usually at least one mag circuit will be bad also.

the control circuit consists of the op-panel, pcb, interlock switch, and wiring.these items are very close to other things we run into so I didn't cover them , but ask if you have any ?, .


NOW YOU MUST USE CAUTION WHEN WORKING ON THIS UNIT IT CAN PUT --you--- IN THE HOSPITAL OR WORST, IF YOU DON'T GIVE IT RESPECT. 4400 VOLTS WILL KILL YOU !!!!!!!!!!!!!!!!!!!!!!!!!

[Just In Time]

the door interlock switches make the fuse in the back blow

[dadtwotimes]

The interlock switch will blow the main fuse in the back as a saftey if you call amana, they will tell you to change the whole interlock assembley not just the mointer switch,