Question about Sharp R-1460 Microwave Oven
Changed bulbs, niether will work. one of the lights acted funny (on off erratic) just before failure. I thought the filament was loose, but issems as a control board problem. 115 VAC is at both sockets. Any help? THx
Check you are getting 115 V with the bulb in circuit (safest way to test this is to solder a couple of bits of wire to one of the bulbs so you can access the terminals with the bulb inline (be careful), and then measure voltage across it.) The load imposed by the bulb may be causing the power supply to go into a protection mode - usually only if bulb is shorting, but may be a problem with the power relay. If there is a problem with the power supply, through the control board relay or otherwise, this will tell you for sure. Otherwise, if there is definitely the right voltage to a good bulb, then it will light. Check that the bulb is definitely making contact well, and make absolutely sure you have the correct bulbs for 115v, not the 220/240v ones. If this gives you no luck then please ask again with details of what you found. Hope this helps :)
Posted on Aug 16, 2007
Only things I can think of are the bulb sockets themselves or the bulb circuit relays. Possibly the sockets are grounding to the chassis?
As mentioned, if a good, correct lightbulb is getting the correct voltage, it will light unless the load it imposes on the supply circuit causes that voltage to shut off or change.
Just possible the relays are both damaged (possibly a power surge) but they could conceivably work for a while when cold. If you can get a part number off the relays if you can identify them, i can try and track down details.
are either or both of the bulbs wired to switch on with the door opening? if so check the door switch - they can often fail - usually corrosion due to over-zealous cleaning or merely overwork.
:)
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OK, I took out the sockets. There is ALWAYS 115 VAC present, the instant the unit is plugged in. When I operate the fan, I hear the panel beeps, and also the relay clicks. When I operate either light control, I hear thr panel beeps, but no relay switching noise
still lightless :(
UPDATE-
put the two light sockets back in, and plugged the unit back in There was only one bulb in the 2 sockets, but light came on, very dim. It would not respond to either switch, and eventually dimmed out. The light bulb works, and the wiring is good. What gives ?
thanx for any help
ken
Just to restate the original problem. The work and night light do not come on. There is ALWAYS 115 volts on the socket. How do the lights get switched on and off? Do the relays supply the ground path? As I stated earlier, after removing and checking both light sockets, one of the lights came on briefly. It was very dim, not controllable with the touch pad switch, and went out shortly. This would indicate that the wiring path is correct, and the bulbs work. The bulbs are a standard replacement from Walmart, I will check and see if some how the rating is wrong.
I have changed the bulbs after failure without unplugging the microwave, could this have been a cause?
I removed the control board, the relays are facing each other. What lettering I can see on one of the relays is this
DUIPU T70
24 VDC (16)5A
250V~
Thanks for any help, hard to troubleshoot by email
I would black box the control board, but it is ~ $160
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