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Electronics => Repair => Topic started by: SEABIRD.HEL on May 05, 2019, 10:18:42 am

Title: Panasonic SC-PT470 home theater
Post by: SEABIRD.HEL on May 05, 2019, 10:18:42 am
I'm at the end of my rope with this one and could use some help, much appreciated!
Schematics and boardview to be found: https://elektrotanya.com/panasonic_sa-pt470.pdf/download.html
I got this unit with defect in the SMPS, after diognostics i replaced:
The diode bridge, input cap, 2 fuses, and the pwm flyback (mip2f2).
The circuit had a short on mainz and after the diodebridge. Both are solved.
Now i have 330VDC on the input cap, all good since here in belgium we have 230VAC mainz. And the device workes. Once i boot the device however the voltage goes up to >600VDC which fries the 400V rated inputcap. I checked the diode, resistor & capacitor for preventing EMI and they check out fine.
Scope image of problem on startup in attachment.

Please help because i'm at the end of my knowledge with this one it seems.
I thank anyone in advance for their help, hope i can return the favor some day!