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Hi,
My out of warranty JWLM 1200 has just expired. Looks like the problem is a blowup in the little SMPSU providing the low volts dc supply to the PCB. Does anyone know what voltage this delivers? I want to try feeding in a separate supply to see whether this will restore function before I just scrap the machine and get a new one.
The PCB is an Electrolux part, various numbers are :
0091_0007G, Artwork or bare PCB? Number in copper etch pattern.
Procond Elettronica 3560130029, number in silkscreen artwork.
Electrolux 132544606
451530305 221010
Boot Ver. B0420009_B 15 55
ENV533054448850, on label with 2d barcodeThere’s a UL file number E74060
Can anyone help?Cheers
Chris
Re: JWLM1200 main control board problem
we don’t get any tech on the boards themselves but id it is the switch mode chips they are cheap and easy to change. you will prob also find the fusible resistor has blown as well
most of them are 12v
look at the relays see what voltage they operate on
Dave
Re: JWLM1200 main control board problem
Thanks for that. They’re 12V relays so I’ll try that.
Fault is odd- plenty of soot in area between SMPS HF TX and main rotary switchmodule but no obviously dead components. Inside switch is all clean. SM IC is on other side of PCB and clean (though probably toast). Made me wonder if a real live bug had got fried and flashed over. Diodes and Rs checked out OK, but no way to check TX for isolation so don’t trust it and no way to replace it.
Chris
Re: JWLM1200 main control board problem
if the board is toast but power supply is ok then measure voltage on the low voltage caps. normally rated 16v or so. Beware the high voltage cap as they hold 350v DC
these power supplies have what is called fold back. if a high current starts to flow the ic shuts down and restarts. if you measure the voltage and it starts to rise then goes lower and repeats this cycle then one of the boards main chips is shorted
beware of another thing. If you put an external power supply on which wont sense a short circuit then you have a chance of overheating something
Dave
Re: JWLM1200 main control board problem
Hmmmm, not so simple. The SMPSU doesn’t generate a single rail. Its HF transformer has a centre tapped secondary feeding a couple of half wave rectifier circuits with a common +ve at the centre tap. Interesting…….
Re: JWLM1200 main control board problem
cetre tapped tx with 2 diodes is a standard single rail power supply. After that they will use a 5 volt reg chip to lower the voltage again
like
https://uk.rs-online.com/web/p/products … lsrc=aw.dsDave
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