A question for the electronics wizzs

[melott]

I have a question about the circuit board in
my wife's microwave oven.
( hay .. at least its not about Windows ) :-D

The microwave oven works fine,  its just the
beeper thats the problem.
I've opened it up and theres a small circuit
board inside for programing cooking time ect.
When you push on any of the buttons its
supposed to make a beep sound, it still does
except you can hardly hear it, and there is no
volume control. The cost of a new circuit board
is out of the question, might as well buy a new
microwave ( this is/was a fairly expencive one
to start with ).
So .. the question is ( educated guess excepted )
is it the speaker or the speaker circuit thats bad??
The speaker is small , about a half inch in dia.
and easy enough to replace but if its the circuit
I wouldn't even know where to start looking.
If I can't fix it, she will live with it the way it is.
But its usually best to try and make the wife happy.

[Lo]

 Not a Wizard, nor do I service Microwaves, but if it is a fairly old unit, it could be that the speaker has grease from vapors in it, but I really don't know..sorry. :-?

[Homer]

Melott,
Probably the sounder itself. Could try a replacement but be very careful of high voltages and radiation inside a microwave oven.
Safe alternative = Buy her a battery powered handheld timer, then she doesn't need to be tied to the kitchen sink ;-)
Good luck  :-D

[Wol]

@ Mellot,


What kind of speaker is it ?

If it is a paper cone with a coil then it could be faulty,
or if it is a solid looking disc (piezo eletric crystal type)
then the fault will prob be with the output transistors and or
driver chip on the circuit board.

That's the best I can do with a keyboard ;-)

Regs: Wol

[shIva]

no solution to your actual problem, but an advise :

NEVER open a microwave oven. the radiation at the so called "chicken frequency" is VERY dangerous for your health. better buy a new one, if you opened the case. its no fun, if you think of what can happen to you and your family if something fails, or just works in an odd way.

[melott]

@ WOL

Yes .. I think it's a solid disk  speaker in a little
plastic case. About one half inch or 1.5 centimeters
diamiter.
I've only taken off the outside cover to see what
is in there, I know the dangers of high voltage ect.
I haven't been poking around, just looking.
The circuit board would be easy enough to remove
but I don't have any test equipment and wouldn't
know what I am looking at anyway.
I just thought if it was the speaker, that would be
just a remove and replace.
But it sounds like more than I can handle so
I guess she will have to live with it like that.

[Stedy]

Does the microwave have a Pegasos inside it?  :-)

Sorry could not resist.

[Jeff]

I could be WAY off base here, but in my boxes of old stuff I should really throw out are some old PC modem cards.  They all have those little speakers on them about the same size as you describe.

Good Luck,
Jeff

[melott]

@Jeff

Thanks for the offer but as WOL said,
its probably not the speaker thats the
problem.
Again .. thanks for the offer

[voytech]

is this small board full of chips?? If not, try to find any transistor (black half-cylinder, with writing on the flat side, with 3 "legs"), this should be what you're lookin for, an amplifier for this small thingy-speaker.. You need to change it to a new one..

The other problem might SMD mounted components, or an amplifier "hidden" in some chip..


-I won't give my hand that this is the problem,
-don't know anything bout microwaves ovens - except how to cook pizza in it..
-soldering ability required!


You should really consider visiting some service - they'll know what to do..