Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

**PlainBill** · 07-07-2010, 07:18 AM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by Spazard

First of all i would to apologize if the question I'm about to ask has already been answered in a different thread and i failed to find it.

Like the title states i have a Philips plasma and it recently decided to die on me. When the unit is plugged in you instantly hear two clicks from the relays and the front green power LED is lit for about two seconds but is then followed by another click and a red LED on the front a panel flashing 6 times. I downloaded the service manual and found out that the flashing light meant it was in protection mode with error code 6 - an issue with the 5v supply. I measured the test points and sure enough no 5V when i plugged in the TV. My guess was that the protection mode kicks in before the 5V can be applied making it seem that there is no 5V when i reality there could be some voltage just not 5V. Naturally i want to say the power supply is either shorted somewhere or something is blown on it but nothing looks physically wrong with it. I've read online people saying that the logic board is the issue while other blaming the small signal board. Bottom line i have read so much different stuff I'm confused and stuck on what to do.

I really hope you guys can point me in the right direction, I hate to put you on the spot PlainBill, but i was hoping you could shine some light on this issue. Your thread on a 12V issue regarding this exact model and chassis type a few months ago encourage me to post on these forums.

Spazard

Well, I will be out of town for a day or two, so spend the time reading the troubleshooting section of the service manual. They document the startup sequence in painful detail.

There are two 5Volt supplies. The 5V Standby supply, and the 5V main supply. The 5V standby supply is up whenever the TV is plugged in. When the standby processor detects a 'power on' signal from the remote or front panel it commands the main supplies on, then starts checking those that are used on the small signal board. When it indicates a 5V supply error, it isn't playing games, being coy, or pulling your leg. It means the 5V main supply is not within specs within the time frame allotted.

A single command from the standby processor starts the power up sequence. (You can trace the signal line on the schematic.) The cause of this could be a short on one of the loads which prevents the power supply from coming up, or it could be the power supply itself.

I would suggest using an analog meter (VOM) or if possible, a fast DMM and check the outputs of the main supply. If any of them start to come up read the service manual carefully; you can usually disconnect the loads to identify the one which is holding the power supply down. Do this in the exact sequence specified.

Other than Panasonic, Philips puts more information into their service manuals than any other manufacturer I have seen. Use it.

Oh, one other point. When the standby processor gets power, it tries to return the TV to the last known state before power was lost. That means it is trying to turn the TV on. Pull the plug, hook up a meter to whatever power supply output you are testing, then plug the power cord back in (a switched power strip is a big help.)

PlainBill

**cadiman** · 07-08-2010, 04:57 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

I have replaced caps on the power supply boards on the phillips 37fd and the 42fd models. The problem was they would not turn on. You would hear the relays click twice
then the power supply would go into protect mode. the 42 was easier to work on. The 50pf model most likely uses a similar power supply also made by phillips. If your board has the mc34067p ic it may also fail. Mine were ok. The service schematic is pretty good for the fd models.

Plainbill made an inportant point about unplugging the power cord to reset the logic. have your meter hooked up to test pionts then power the tv up to check v. you will have about two to three seconds to check stuff before going into protect mode each time.

I am picking up a 42pf model next week so this will be good!

**Spazard** · 07-08-2010, 11:33 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Well i have been having a very hard time tracing the signal, I've been looking at the schematic for hours trying to make sense of it but it's obvious i have forgotten everything i learned back in school. I do have 5V standby (5.3V to be exact) and i also tested all the test points i saw labeled 3V, 5V and got reading of .2V or less before protection mode kicked in. I'm gonna keep studying the service manual and see what more information i can find or if i manage to figure our the signal path.

From what i read i suspect the DC/DC converter might be the issue but i have let to find a safe way of testing it without compromising the ground to the AC supply.

I'll post a update soon with more info (if i manage to figure anything out)

**cadiman** · 07-09-2010, 05:22 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

I stand corrected. The pf9431 series looks more like a samsung power supply.

It may take a weekend and a few beers. Make copies of the schematic and use a highlighter to trace. You will figure it out. Did you find out how to remove power from the y and x boards to see if the power supply stays running?

**PlainBill** · 07-09-2010, 11:50 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

For an explanation, start at the bottom of the left column of page 37 and continue on to page 38 of the service manual. It gives a brief description of the DC - DC Converter.

Page 47 shows the power distribution. Don't spend too much time on this page; it's mainly for the Small Signal Board, and other Philips supplied parts. It DOES show the power control takes place on B4E (page 68 of the SM).

ALSO, download the service manual for the panel. Read it through once before continuing. Page 23 of the PDF has the test procedures for the panel. Be very careful. It is possible to get up to 400 volts through your body while fooling around with these cards. Also, the procedure calls for testing with one cable at a time unplugged. Follow those directions.

PlainBill

**Spazard** · 07-12-2010, 09:36 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

I read through the pages you suggested about the DC - DC converter and i wanted to measure the input voltage via the decoupling capacitors. However i don't see how i can do that without removing the I/O shield and from what it seems if i do that, i lose ground for the AC input and possibly the SSB. I did test the PSB with each cable unplugged in order and all together and got the same code 6 error and protection mode except when i unplugged the SSB. when i did that i would get no error code or protection, instead i would get LED 8001 on the PSB to flash 3 times constantly but still no reaction from the TV itself.

So far all the labeled test points (1M46 too) are only showing a voltage 0.2V or lower other than the 5V standby. Considering the voltages on plug 1M46 are close to non-existent i want to say the power supply is the issue plus i don't understand how to test the SSB correctly. I'm honestly thinking of just buying or sending in the Power supply board for repair. But then again i don't know where to send it or maybe Bad Caps repair services can figure it out.

I really wanted to do the repair myself but its obvious I'm struggling to the point of embarrassment, i am sorry to both you PlainBill and Cadiman if i have wasted your guy's time.

I haven't given up completely though!

**PlainBill** · 07-12-2010, 10:10 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by Spazard

I read through the pages you suggested about the DC - DC converter and i wanted to measure the input voltage via the decoupling capacitors. However i don't see how i can do that without removing the I/O shield and from what it seems if i do that, i lose ground for the AC input and possibly the SSB. I did test the PSB with each cable unplugged in order and all together and got the same code 6 error and protection mode except when i unplugged the SSB. when i did that i would get no error code or protection, instead i would get LED 8001 on the PSB to flash 3 times constantly but still no reaction from the TV itself.

So far all the labeled test points (1M46 too) are only showing a voltage 0.2V or lower other than the 5V standby. Considering the voltages on plug 1M46 are close to non-existent i want to say the power supply is the issue plus i don't understand how to test the SSB correctly. I'm honestly thinking of just buying or sending in the Power supply board for repair. But then again i don't know where to send it or maybe Bad Caps repair services can figure it out.

I really wanted to do the repair myself but its obvious I'm struggling to the point of embarrassment, i am sorry to both you PlainBill and Cadiman if i have wasted your guy's time.

I haven't given up completely though!

Welcome to the club!!! Frankly, the power supply on most 32" or larger LCD TVs are a pain to troubleshoot. The power supplies on plasma TVs are at least an order of magnitude more complex. One problem is for the most part no schematics are available. A second problem is there are a number of power supplies that must come up in a specific sequence or the supply shuts down. I spent all my free energy for a week on the power supply for an LG TV, and finally came to the conclusion that every diode was good, every capacitor had a reasonable ESR, and there were no components that were obviously bad. I finally gave up and bought a new power supply.

The part you want is Philips # 996500036821 or LJ44-00118A. Do make sure you get a warranty.

PlainBill

**el3ctroded** · 07-13-2010, 04:36 AM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by PlainBill

I spent all my free energy for a week on the power supply for an LG TV, and finally came to the conclusion that every diode was good, every capacitor had a reasonable ESR, and there were no components that were obviously bad. I finally gave up and bought a new power supply.

That's a relief! I thought it was just me having those sorts of problems. It's really frustrating! I just gave up on the 32" vizio I've been posting about and bought a practically new one with a broken screen for about the cost of the PSU alone. Swap boards and hopefully all will be well!

**PlainBill** · 07-13-2010, 07:08 AM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by el3ctroded

That's a relief! I thought it was just me having those sorts of problems. It's really frustrating! I just gave up on the 32" vizio I've been posting about and bought a practically new one with a broken screen for about the cost of the PSU alone. Swap boards and hopefully all will be well!

No, it's not just you. I firmly believe with a good schematic of the power supply I could have fixed it. One problem was several modules that apparently comprised the SMPS controllers. And the fact that I have been unable to dig out my isolation transformer didn't help. I'm sure the factory has a set of dummy loads, and can isolate the various sections to allow troubleshooting.

Hmm, now that I think about it, sometime I should analyze a schematic of an LCD TV's power supply and see how to disable the interaction.

PlainBill

**Spazard** · 07-14-2010, 11:20 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by PlainBill

Welcome to the club!!! Frankly, the power supply on most 32" or larger LCD TVs are a pain to troubleshoot. The power supplies on plasma TVs are at least an order of magnitude more complex. One problem is for the most part no schematics are available. A second problem is there are a number of power supplies that must come up in a specific sequence or the supply shuts down. I spent all my free energy for a week on the power supply for an LG TV, and finally came to the conclusion that every diode was good, every capacitor had a reasonable ESR, and there were no components that were obviously bad. I finally gave up and bought a new power supply.

The part you want is Philips # 996500036821 or LJ44-00118A. Do make sure you get a warranty.

PlainBill

I hate giving up on a project but i feel better knowing that its not because i didn't try every everything i knew including asking for help. Your right about how complex TV power supplies are and i accept defeat on this one. I plan on buying a new one this weekend.

Its odd that every website i check ends up giving a replacement number that matches what you suggested (Philips # 996500036821 / LJ44-00118A) or (Philips # 996500042147 / LJ44-00125A). I have LJ44-00125A but i read that both parts are interchangeable. But numerically i would assume what i have is a newer revision but i could be wrong.

**PlainBill** · 07-15-2010, 04:46 AM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by Spazard

I hate giving up on a project but i feel better knowing that its not because i didn't try every everything i knew including asking for help. Your right about how complex TV power supplies are and i accept defeat on this one. I plan on buying a new one this weekend.

Its odd that every website i check ends up giving a replacement number that matches what you suggested (Philips # 996500036821 / LJ44-00118A) or (Philips # 996500042147 / LJ44-00125A). I have LJ44-00125A but i read that both parts are interchangeable. But numerically i would assume what i have is a newer revision but i could be wrong.

A word of explanation on these part numbers. First of all, you understand that Philips buys the plasma panels assembly from, in this case, Samsung. This includes the plasma panel itself, the buffers, sustain boards, main control board, and the power supply. Philips supplies their own chassis, small signal board, audio amp, speakers, side input board, etc.

As part of the deal, Samsung takes their standard power supply and modifies the design to supply the voltages the customer needs for their small signal board and audio amp. That power supply has at least three numbers - the bare board number, the 'stuffed' board number, the customer (Philips) stock number and possibly the Samsung stock number. The first two numbers are usually the only ones visible in the final product. The Philips number is the only one found in the service manual.

To further complicate matters, at some point Samsung may identify ways to improve the power supply design, or simply redesign because a part is not available. The new would have the same physical dimensions and connectors, but different part numbers are assigned to it.

PlainBill

**cadiman** · 07-19-2010, 10:29 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

I have worked at the dealer level in automotive and turf (golf course equipment).
I had information you can`t get outside the dealer. It`s the same way with electronics. If you had the same info the tv techs had you would have everything you needed to repair the tv.

Even then it can still be hard to troubleshoot and repair.(They warranty the board after they burn it up) also they have a pile of new boards on the shelf.

**InBar** · 11-12-2010, 10:50 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Did you ever figure out the problem with the 6 Blinking Lights for the Philips Plasma. I have been told two different things that it could be. Which is the Power Supply (which I changed) or the SSB (small signal board). I also have changed the logic board. Most people have problems with the capacitors however, they look good to me. Even with the power supply and the logic boards changed I still get 6 blinking lights. I would change the SSB if I believe this would fix the problem.

I also do not like to give up, so would like to figure this out. Thanks if you have any suggestions.

**PlainBill** · 11-13-2010, 11:28 AM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by InBar

Did you ever figure out the problem with the 6 Blinking Lights for the Philips Plasma. I have been told two different things that it could be. Which is the Power Supply (which I changed) or the SSB (small signal board). I also have changed the logic board. Most people have problems with the capacitors however, they look good to me. Even with the power supply and the logic boards changed I still get 6 blinking lights. I would change the SSB if I believe this would fix the problem.

I also do not like to give up, so would like to figure this out. Thanks if you have any suggestions.

The service manual is at www.elektrotanya.com. It indicates that 6 blinking lights indicates a problem in the 5V supply. The presence of the 5V supply is detected on the Small Signal Board. Troubleshooting this should be trivial. Download the service manual for reference. There is an 11 pin connector on the power supply that is connected to the small signal board by a cable. Check for the presence of 5V at this connector. If it is present, start tracing it through the SSB. If it is missing, check why - POSSIBLY the X buffer.

PlainBill

**InBar** · 11-13-2010, 06:49 PM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Yesterday after the post I did some more test and I disconnected the Y Sustain power cable and left the SSB connected. After turning on the TV the 6 blinking lights are gone and the TV green lights stay on. So I believe it either the y sustain board or the buffer boards. I am trying to figure out how to test these boards with a multimeter (if this is possible).

**PlainBill** · 11-14-2010, 06:06 AM

Re: Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Originally posted by InBar

Yesterday after the post I did some more test and I disconnected the Y Sustain power cable and left the SSB connected. After turning on the TV the 6 blinking lights are gone and the TV green lights stay on. So I believe it either the y sustain board or the buffer boards. I am trying to figure out how to test these boards with a multimeter (if this is possible).

Hint: Check which of the power supplies are being overloaded by the Y-sustain. Trace where it goes on the Y-Sustain. Find the defective component.

PlainBill

Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

Philips Plasma 50PF9431D/37 Chassis BJ2.5UPA

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