Phillips Plasma dead or alive

[oldjag42]

Gotta free Phillips plasma mod. 50MF231D/37, chassis EP1.1U, that the owner replaced two 16V 3300uf caps on, (C8059 & C8060), on the PSU or power supply board. No/picture or sound. So far I've downloaded the service manual, but alas, the main power supply is not included in the schematic, but for some odd reason the DC to DC converter on the SSB is???

Main power fuse was blown, but replaced and it holds. 1V, 3V, 12V, 18V, 200V supplies power up and ripple looks okay, but error 14, (Audio supply Class D amp) is shown when SDM or service diagnostic mode is entered.. green front panel led shows 1 long flash & 4 short.

Voltage on audio amp supply rails is +11.9 & -11.9. Voltage on speaker wires is ~0.05volts. Leds 8001 & 8002 on PSU are both on steady which I think is good. The DC_PROT line between the PSU board and the SSM, (small signal board) is at 0.06V. On the SSB I can't seem to get on the U_Volt-Detect, H_Volt-Detect or Prot_Audio supply lines to measure powered up, as this is on the bottom of the SSB..unmarked surface mount components, very small and hard to reach while connected etc. Anyone fix a similar error problem on this unit? Seems a shame to trash it...

Thanks

[PlainBill]

Re: Phillips Plasma dead or alive

I've not worked on that particular model, but the class D audio amp was a weak point in Philips TVs. One quick test is to unplug the audio amp.

The reason the power supply isn't included in the service manual is it's a part of the plasma panel - supplied by Samsung.

PlainBill

[oldjag42]

Re: Phillips Plasma dead or alive

The audio amp is on the SSB along with logic circuits for protection, DC to DC converters for 1v,2v and 3v, but its connected to the PSU via a cable, (connector 1M02). I pulled the cable and powered up the set. No more error 14 with connector off. If I put it back on the error 14 comes back. The voltage on the PSU with or without the audio amp connected is 11.95V. If I try to turn the 12V pot on the PSU up more than about 11.97V the PSU shuts down and an LED on the PSU alarm board puts out 2 flashes followed by a pause. This happens with the audio amp connected or not. Somehow the 11.95V and the fact that it can't be turned up to say 12V or even 12.5V maybe seems suspect since the factory as checked voltage tag on the panel says it was set 12.5V.

[oldjag42]

Re: Phillips Plasma dead or alive

More info. I found a web site with some Phillips PSU service info. Jumpers on CN1MO2, pins 7 & 4 and CN8006 pins 2 & 9 plus DIP jumper on RH set of DIP pins on PSU alarm board, allow stand alone operation and alarm board error code readout via alarm board LED. (Not to be confused with the front panel LED flashing codes). Ran test, no error codes stand alone - BUT - adjusting 12V pot to over 11.97V triggers 12V over voltage alarm on PSU alarm board. (two flashes on LED). I think the alarm board is called an HIC8001 and the 12v seems to be monitored as a 2 to 3 volt signal on Pin 5 so I guess I'll check that next...still not certain PSU is really the issue, or the only issue.