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Registered Member #1361
Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305
Hi, i have a microwave here that ended up with water inside, and my desicion was to buy a new one to be on the safe side. THough, what I do have now is a big useless MO. I ripped the casing off (Keeping in mind there is a cap in there) and found a HUGE MOT!
Once I have the capacitor disconnected I will feel safer, but how do you guys drain the capacitor? I dont have any HV resistors here or anything, and I am afraid of just shorting the thing. Any ideas? I could stick a screwdriver on the end of a wooken stick or something and short it that way, but I am open to suggestions on how to safely get the MOT out.
EDIT: I will most likely be rewinding it for low voltage and high output. Unless I can severely ballast it, it has too much current output for me
Another EDIT: There appears to be a bleed resistor on it. THe microwave hasnt been plugged in for about a week. Anyone know how long it usually takes the resistor to completely bleed the charge?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I think that everyone here on this electronics forum would tell you to repair the old MO (should be easy)
But it's your decision anyway. I haven't seen a single capacitor without resistor, so it should be drained already. If you want to be safe just short it with a well insulated screwdriver, if its charged it will make a loud pop.
P.S. How big is the MOT? I like to indirectly measure the power by secondary resistance, any chance you can tell me yours?
Registered Member #1361
Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305
I already have a new MO, so its OK. I got a quick pic of the MOT, it seems pretty big. mod edit: bloody strewth mate! lay off the oversized pictures and double posting
Registered Member #1361
Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305
Oh well, After alot of fuss, I grabbed a screwdriver and shorted the cap. Nothing happened at all! Anyway I have the MOT. It has 3 wires, but I have figured out which is which. Here is a pic:
EDIT: Just realised there is a filament winding with about 2 turns. What kinda voltage/current can I get outta that winding?
Eventually I was thinking i'd scrap the HV windings and make it low voltage/high current
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
That MOT realy does not look that big, is it 60 or 50Hz? If 60 you can expect a bit higher powers from the same sized transformer. Anyway I don't think it is good for anything over 500W continuous without melting (I guess the power of the original oven was ~700W?) Of course if you include a fan, it will handle bigger powers like in the MO.
Registered Member #1630
Joined: Sat Aug 09 2008, 11:36AM
Location: Seoul Korea
Posts: 115
actually that MOT looks to be one of those big dudes I used to see here before they went digital. Those xmfrs are easily 2kw each. Small 500-700W XMFRs do not have that big a core on them. Also these are secondary side ballasted with the capacitor.
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Help with dissecting a MO?
(and I do NOT call this a big MOT 