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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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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 |
#2
Posted to sci.electronics.repair
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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. |
#3
Posted to sci.electronics.repair
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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. |
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