Philips 32PFL3008H/12 repair, blown PSU, Vestel 17IPS19-5P, SMD resistors

[Chungalin]

This 32" LED Vestel has blown 3.15A fuse, two RL207 diodes from rectifier bridge, switching regulator Infineon ICE3BR0665J (IC303), a zener diode (D314, SOD-123, marking "WE", possibly 9.1V zener), and burnt SMD R301, R302, R303 & R304 in parallel. R302-R304 are 2.7Ω (from marking), but R301 is unreadable. I could guess that all four are the same, but the remnants of R301 marking make me think this one could be different. Perhaps 3.3Ω? These resistors are connected to Current Sense pin of IC303.

I've searched schematics of 17IPS19-5P and there're slight differences with mine. Resistors are all 2.2Ω and IC303 is ICE3BR1765J instead. Not surprising, since "17IPS19-5P" is PCB name, not actual PSU code. Different components can be fitted in same PCB producing different circuits for smaller or larger backlights. I think that PSU code is 23095011 (from a paper label) and Philips code is 9965-900-05964.

Anyone have a board like this and can confirm these resistors, please? Or, is it that important if it's 2.7Ω or 3.3Ω? They're in parallel, so we're talking about an equivalent of 0.68Ω or 0.72Ω.

[budm]

Re: Philips 32PFL3008H/12 repair, blown PSU, Vestel 17IPS19-5P, SMD resistors

The CS resistance will determine what the current will be to trip the protection.
I.E. lets say that you want the protection to kick in when the current through the resistor is 1A, so if we use 1 Ohm so at 1A you will have 1Vdrops to trip the circuit, but if you replace the resistor with 0.50 Ohms then the circuit will not trip until the current through the resistor is at 2A.

[Chungalin]

Re: Philips 32PFL3008H/12 repair, blown PSU, Vestel 17IPS19-5P, SMD resistors

Thanks. I’ve put a 0.68Ω axial resistor and it’s working fine (replacing all other components, of course). If that resistor determines current limit for switching regulator, then I think that 0.04Ω tolerance won’t be a critical deviation.