I just fixed second TV today, (different brand and design, different owner) but the SMPSes are based on same design made by FSP (slight differences but it is unmistakable. Usually I see this in 32" sets.
Well, this would be no big deal to replace bad caps but I also had to repair them because of (out of control) design even it had good IC used but that particular IC doesn't protect against bad caps.
Standby SMPS had bad caps on cold side, that destroyed usually 2 or 3 components in hot side (15-16V Zener sets a 2N2222 style SMD transistor to around 14V-15V output fed by a diode in hot side from standby this fed standby IC controller and this 15V source sometimes a 5R1 resistor burnt and small cap (not the bad cap itself). This output in turn feed a PNP transistor controlled by a optisolator from mainboard (on/off control). This goes on to the PFC. Once PFC comes up, thus generating a turn on voltage to SMPS. The main SMPS comes up. Chaining these together in sequence. :P
Not very good design IMHO.
Cheers, Wizard
Well, this would be no big deal to replace bad caps but I also had to repair them because of (out of control) design even it had good IC used but that particular IC doesn't protect against bad caps.
Standby SMPS had bad caps on cold side, that destroyed usually 2 or 3 components in hot side (15-16V Zener sets a 2N2222 style SMD transistor to around 14V-15V output fed by a diode in hot side from standby this fed standby IC controller and this 15V source sometimes a 5R1 resistor burnt and small cap (not the bad cap itself). This output in turn feed a PNP transistor controlled by a optisolator from mainboard (on/off control). This goes on to the PFC. Once PFC comes up, thus generating a turn on voltage to SMPS. The main SMPS comes up. Chaining these together in sequence. :P
Not very good design IMHO.
Cheers, Wizard
