Troubleshoot SMPS in Zenith TV...again!!!
 

Hello Everyone;

Once again I am still having trouble with a Zenith Model: A32B41W (9-2003) TV set...a wire-wound sand block? power resistor (5W, 0.68ohm RX3401) keeps burning up immediatly when the unit is plugged in. I got the schematic and looked over the power supply section and the resistor that connects to the bridge rectifier (DX3401) and supplies the ground (-) is the trouble maker. This is the set that was killed by too much input voltage (240 not 120). I replaced some components including the 470uF (CX3405) main filter cap and couple other resistors. I don't understand what keeps burning this resistor...any ideas???

Would the HOT (1167-01) be responsible for shorting the power resistor?

Also, If you want to have the full (1MB) .PDF schematic for Zenith GB series, contact me through email and i'll send it to you.
Ejohnson1486(at)yahoo(dot)com
Thank You for any help

Troubleshoot SMPS in Zenith TV...again!!!
 

Did you just forget to mention it or, didn't you change the regulator
and driver transistor yet? That resistor is a surge resistor and the
only thing from keeping the fuse from blowing. The reg. is an STR53041
and I forget the driver number except it's a Motorola. Also, there's a
100uf and a 22uf cap that needs changing and you're done. The other
components in the power supply should be just fine.

Troubleshoot SMPS in Zenith TV...again!!!
 

I think you can measure pins 3 and 4 for a short but, doesn't matter.
It's bad and so is the driver transistor and the two electrolytics.

Hey, I pulled the STR53041 regulator off the board and the replacement .68ohm 5W power resistor didn't burn up this time...now, how do I test this STR53041 regulator? Just to make sure it is bad. I only have an ohmmeter (AKA: multimeter) Thanks, Johnson