Sharp Oven KB4425LS Need Assistance

[computerpulse]

Ok folks working on a Sharp KB4425LS Oven.  I have absolutely no display or control panel.  Sharp had me replace the control panel but this did absolutely nothing.  I suspect the power board, I have ohmed the low voltage transformer and it ohms ok.  I am a little confused by Sharps schematics and wondering if someone out there can look this over and give me some ideas how to verify the power board or steer me in the right direction.  I would prefer to prove the fault rather than guess the fault.  Any assistance would be greatly appreciated.

email me for the service manual if you require this.  It's too big for here.

[RegUS_PatOff]

Thanks, I got the manual...

There should be about 12 volts AC volts on the output of the LOW voltage transformer, yellow - blue wires.

(A1 - A2 on the control unit)

edited: There should be 24 volts DC volts on the output of the switching power supply unit,  pins 1 (gnd) - pin 3

( E1 - E2 on the control unit)

 

 

[computerpulse]

I have nothing on the blue and yellow wires off the transformer

and I have 24VDC on pins 1 & 3 on the switching power supply(which I thought was the inverter)

For that matter I am not reading anything on the white and black on the transformer either

 

[jambatt]

The oven wiring diagram shows a thermal cutout(fuse). Part # 4-43 in Oven Parts List. Should have two red wires. Check for continuity.

[computerpulse]

I thought this was the oven thermistor but this has 2 orange wires.  I have not been able to find the two red wires.  any ideas?  I have not seen it in the manual.  All manual fuses have been checked and test ok

 

[computerpulse]

I Found that darn thermal fuse.  It's buried.  I have to take this whole stinkin thing apart to get to it.  Damn Sharp!  No wonder they only have a couple of hundred of these sold.  I will let you know what happens tomorrow.  I am going to bed now.  But I will bet my bottoms that this is the culprit.  Thanks for your assistance

[jambatt]

Look at the Range Schematic Oven page 18 of the PDF. Your're correct about the thermistor having orane wires. Look at the bottom of the schematic and you will see the thermal cutout with two red wires. Go to pages 71 and 72 of the PDF for the Oven Parts List. Look for part #4-43. It's located on top of the oven toward the left rear corner.

[computerpulse]

Well I finally got to the culprit.  Had to dismantle quite a bit to get to it.  I thank you all for your assistance.