Protron PLTV-32c

[mrosenberg42]

Hello all,
I have a Protron PLTV-32c that has no standby power or any other voltages for that matter. I read the posts about the PLTV-3250 and it sounds like the same issue but a different power supply. I checked all transistors, diodes, zeners and found no bulging caps. Everything checks out ok. Granted everything was checked in circuit and no components have been pulled off the board and checked, which will be my next move. I think I'll start with replacing all electrolytics and then pulling off zeners and checking them outside the circuit. Does anyone by chance have a schematic of this power supply: FSP232-4M01. These surface mount diode and transistor markings are cryptic. Color bands are hard to read etc. It would be much easier to be able to reference a schematic. Anybody else have the same issue with this LCD or have any suggestions? Would be much appreciated. Thanks.

[PlainBill]

Re: Protron PLTV-32c

Hello all,
I have a Protron PLTV-32c that has no standby power or any other voltages for that matter. I read the posts about the PLTV-3250 and it sounds like the same issue but a different power supply. I checked all transistors, diodes, zeners and found no bulging caps. Everything checks out ok. Granted everything was checked in circuit and no components have been pulled off the board and checked, which will be my next move. I think I'll start with replacing all electrolytics and then pulling off zeners and checking them outside the circuit. Does anyone by chance have a schematic of this power supply: FSP232-4M01. These surface mount diode and transistor markings are cryptic. Color bands are hard to read etc. It would be much easier to be able to reference a schematic. Anybody else have the same issue with this LCD or have any suggestions? Would be much appreciated. Thanks.

There are a few (very few!!) schematics of TV power supplies floating around. From the few I've seen, the standby supply is usually a very simple supply. I'd suggest treating that as a simple power supply and starting with the basics. Make sure the main filter cap has the proper voltage (1.4X line voltage), the SMPS chip is getting appropriate voltages, and the output diode and load aren't shorted.

Pay particular attention to small electrolytic caps around the SMPS IC. Because of the 'bootstrap' design of these supplies an open cap can prevent the standby supply from even starting.

PlainBill

[mrosenberg42]

Re: Protron PLTV-32c

Thanks for the reply. I did check ESR of all electrolytics and all measured ok. The filter Cap is at 160v which is 1.4x as you suggested. I am definitely missing something. I still don't trust any of the caps. Like I said earlier I'll start with recapping the whole supply check the smps chip voltages and then work through the other components one by one. Thanks again.