[jcyeandle]

Hello, it is with much thanks and satisfaction that the replacement shottky diode (LV side of control board) as suggested by Dave of Electrofix, has brought the control board back to life and we will now have a functioning microwave oven for Xmas

I really appreciate all of the help that this site can provide folk like me. In particular, Dave’s freely given assistance has enabled me to save a perfectly good appliance from the tip and given me enormous satisfaction (and saved me some cash).

Of course, I’ll get some kudos from the family and we’ll all get the opportunity of warm mince pies:p

Many thanks Dave and a very merry Xmas to you and yours, and to all of the helpers here,
Kind regards,
Jonathan

[jcyeandle]

Two replacement shottky diodes now ordered and fingers crossed for a funtional microwave for Xmas.

I’ll report later…

Jonathan

[jcyeandle]

Hello Dave,
thanks for looking at this.
Yep, that sounds about right although the IC is possibly doing a little more than just doing the high frequency chopping job.? The opto-isolator goes directly to pin 5 of the LC1206A and is possibly a not-enable line from the controller?

I do get the 340vDC or so.

The shottky diode is a very good lead – thanks. One of them conducts both ways:-) Hopefully I’ll be off and running once I track some replacements down.

I’m in the middle of some plastering right now but hopefully get some time at the weekend or evening and I’ll update you.
Good man,

Kind regards,
Jonathan

[jcyeandle]

Hello Dave and thanks for taking time to reply and I am guilty as charged!

I concur, the board needs its 5v for the control part to function.

I’m struggling to work out what and how the primary windings of the transformer are being driven and it doesn’t appear to be ‘standard’ ie. line and neutral supplying the necessary AC being transformed/stepped down to say 12vAC. The only direct(ish) connection to the primaries is via the LC1206A which presumably outputting some form of digitally constructed and maybe shaped square wave. Judging by the size of the transformer (tiny/board mounted) it is being driven at far more than 50HZ, but I could be wrong. Probably am.

I failed to upload my de-constructed circuit here and I see that there is very small size limit. I have no/do not use web storage but I could email it somewhere?

I could easily lash up a 5V DC supply off board but don’t feel that is the fix that I need. Neither have I been able to find an equivalent transformer (tried the Galanz web site and others).

Maybe this HV circuit design is too obtuse.

Kind regards,
Jonathan

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