Philips Plasma 42" troubleshooting help?

[Corbino]

Hi guys,

I've got a model 42PF9631D/37 Philips Plasma TV. Chasis number BJ2.5u PA. This unit goes into protection immediately after being plugged in. The power button does nothing to change the symptoms. The red LED is displaying 7 short blinks then pauses, then repeats. I cannot see a long blink in the pattern. Sounds like a code 7 to me??? This code "7" has a description of "8V6 supply" in the service manual.

I have another TV just like this one that I've repaired by replacing two caps (C8059 &. C8060). I took the power supply board out of the working TV and put it in the bad TV and it came up normal. I then replaced the same two caps on the bad board and the symptoms are the same.

At this point my questions are...

1. When it comes to this power supply board are ther specific caps, transistors, etc that should be suspect first simply due to common failure? i.e. C8039, D8040...

2. This afternoon I'll be looking for the service manual for the power boards. Does anyone have a link? If i find it I'll put the link up here.

[PowerAmpFreak]

Re: Philips Plasma 42" troubleshooting help?

So, the red protect led on the powersupply board is not blinking? This powersupply has a failure diagnose feature which will output a code by a blinking sequence. But you mean the standby led on the front?
Did you measure the 8V6?

Try finding a service manual according to panel and NOT model of TV.
You know, the manufacturer of the panel also provides the drive boards and most often the powersupply board. These will not be found in a service manual for the TV modell. Often, only the SSB is included.

Try elektrotanya.com

[Corbino]

Re: Philips Plasma 42" troubleshooting help?

I'll check the light on the board. This above blinking code description is from the front "standby" LED indicator. I'll also get a measurement on 8V6 when I get home from work here in a few minutes.

Striking out on finding that panel service manual. I'm assuming that the Assy Code on the board (LJ44-00117A) would be what I search for? There is also a PS-425-PH Rev 0.2, but I've not found it yet with either.

Thanks for the reply!

[PlainBill]

Re: Philips Plasma 42" troubleshooting help?

That set uses a PDP S42AX-YD02 plasma panel assembly. The service manual for it is available at elektrotanya. It does give some information on what to check on the power supply.

I would suggest also searching Scribd and Electotanya for that panel number. If I recall correctly, there is a second manual that covers more detail on the panel. It was of limited use to me because it was in one of the many languages I cannot read - Spanish.

PlainBill

[Corbino]

Re: Philips Plasma 42" troubleshooting help?

Wow! Thanks Bill! I would have been plunking around for days looking for that!

I found Zero volts at 8V6 with system plugged in and in protect mode. I'll check all of the voltages in this manual for my board. Should I put it in Service Mode for this? For some reason I get the feeling that all of these points might be without voltage due to protect???

There are two green LED's on the board that do not light up when the system is plugged in and in protect mode. I hear a slight ringing sound from the Hot side of the power board that varies with the blinking of the standby (front) LED. So, there are no blinking lights on the board at all.

[PlainBill]

Re: Philips Plasma 42" troubleshooting help?

Wow! Thanks Bill! I would have been plunking around for days looking for that!

I found Zero volts at 8V6 with system plugged in and in protect mode. I'll check all of the voltages in this manual for my board. Should I put it in Service Mode for this? For some reason I get the feeling that all of these points might be without voltage due to protect???

There are two green LED's on the board that do not light up when the system is plugged in and in protect mode. I hear a slight ringing sound from the Hot side of the power board that varies with the blinking of the standby (front) LED. So, there are no blinking lights on the board at all.

You might as well troubleshoot it in the TV. Here's the usual sequence. The TV is plugged in. The standby processor does a few checks, then turns on the power relay. It does more checks, including checking certain voltages. If any of the power supply outputs test out of spec, the standby processor shuts down the power supply and flashes the error indicator. So you have only the few seconds between the power going on and the power supply shutting down to check the output voltages.

PlainBill

[Corbino]

Re: Philips Plasma 42" troubleshooting help?

The TV is plugged in. The standby processor does a few checks, then turns on the power relay. It does more checks, including checking certain voltages. If any of the power supply outputs test out of spec, the standby processor shuts down the power supply and flashes the error indicator. So you have only the few seconds between the power going on and the power supply shutting down to check the output voltages.

PlainBill

In this case the relay is not turned on. There is no click.

[PlainBill]

Re: Philips Plasma 42" troubleshooting help?

In this case the relay is not turned on. There is no click.

Then it should be (relatively) easy to troubleshoot. You have demonstrated that the problem is the power supply. That eliminates the Small Signal Board (which contains the standby processor, which controls the main power supply AND the front panel LED). The TV works properly when a known good power supply is installed. Now, I am not familiar with every (or even most) power supplies used in Philips TVs, but every one I am familiar with uses a relay to control the main power supply. To be clear, the power supply board contains a standby power supply and a main power supply. The standby supply is on whenever the TV is plugged it.

As I recall, the connectors are labeled on the power supply. The schematic for the Small Signal Board clearly shows the control line to the main power supply. I would suspect a cracked land, an open transistor , or some similar problem that results in the drive signal to the relay not triggering the relay.

I agree, this may not be an easy job. Troubleshooting plasma TV power supplies is one of my least favorite occupations.

PlainBill

[PowerAmpFreak]

Re: Philips Plasma 42" troubleshooting help?

Depending on circuit topology - it might be possible to jump start the relay or shorting its contacts, to see if this might wake up the powersupply.
Or use a separate switch across the relay.
You did verify that standby supply is working properly right?