Philips 42 Plasma 7 blinks 42PF7220A /37

[DakotaKid]

Philips 42PF7220A/37 42" Plasma, Chassis BP2.3U.AA, mfg 4/06

This TV is flashing the 7 red led error message on the front panel indicating a power supply problem I believe. I opened it up expecting to find bulging 3300 uf caps in the power supply circuit but they appear ok, at least not visibly bulging on their tops. I have a couple of new 3300 uf 16V caps that I could go ahead and put in but I would like to do the proper troubleshooting first unless someone here advises me differently. I'm just not sure where I should start as far as checking voltages or what values I should be looking for.

I have no fear in tackling this one. I have a DMM and can use it, I have a decent amount of soldering experience, I am pretty good with electronics, and I am overall very handy. I just don't know a lot about these TV's other than the easy visibly bad cap repairs. This is my 3rd plasma to resurrect with the first two being successful. I'd like to get this one done because I've already acquired my NEXT project! It's a 55" Mitsubishi rear projection with what I believe is bad power supply caps...but it has to wait for another day.

Any help on this Philips would be greatly appreciated. Should I go ahead and replace the two caps in case they are bad, just not visibly bulging?

Thanks in advance.

DaKid

[PlainBill]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Philips 42PF7220A/37 42" Plasma, Chassis BP2.3U.AA, mfg 4/06

This TV is flashing the 7 red led error message on the front panel indicating a power supply problem I believe. I opened it up expecting to find bulging 3300 uf caps in the power supply circuit but they appear ok, at least not visibly bulging on their tops. I have a couple of new 3300 uf 16V caps that I could go ahead and put in but I would like to do the proper troubleshooting first unless someone here advises me differently. I'm just not sure where I should start as far as checking voltages or what values I should be looking for.

I have no fear in tackling this one. I have a DMM and can use it, I have a decent amount of soldering experience, I am pretty good with electronics, and I am overall very handy. I just don't know a lot about these TV's other than the easy visibly bad cap repairs. This is my 3rd plasma to resurrect with the first two being successful. I'd like to get this one done because I've already acquired my NEXT project! It's a 55" Mitsubishi rear projection with what I believe is bad power supply caps...but it has to wait for another day.

Any help on this Philips would be greatly appreciated. Should I go ahead and replace the two caps in case they are bad, just not visibly bulging?

Thanks in advance.

DaKid

The service manual is available at www.elektrotanya.com. If the set has the latest firmware, 7 blinks indicates a problem with the 8.6 volt supply. If the two 330 uF caps are Samwah's I'd replace them.

PlainBill

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Samwha's they are! I will replace them when I get a chance and report back with results. Meanwhile, thanks for the link to the manual, I'll have a look at that too.
DK

[PlainBill]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Samwha's they are! I will replace them when I get a chance and report back with results. Meanwhile, thanks for the link to the manual, I'll have a look at that too.
DK

While you're there you should also look for the service manual for the plasma panel. I believe that set uses a S42AX-XD02 or S42AX-YD01

PlainBill

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Replaced the two 3300 uf caps on the main board, no change. A few more details about what I observe now (and same as before)...the two green leds near where the input power leads plug into the board light up for about 5 seconds after two clicks are heard. After 5 seconds or so they go off and the front led starts flashing the 7 red flashes and repeats this. A small circuit card attached to the main board has a green led that flashes 3 times and repeats this over and over. Down on the lower board, the one that connects to all of the audio / video outputs also has two micro leds, the first comes on green when the other two do, the other flashes for the same 5 seconds until the main power shuts down.

DK

[PlainBill]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Replaced the two 3300 uf caps on the main board, no change. A few more details about what I observe now (and same as before)...the two green leds near where the input power leads plug into the board light up for about 5 seconds after two clicks are heard. After 5 seconds or so they go off and the front led starts flashing the 7 red flashes and repeats this. A small circuit card attached to the main board has a green led that flashes 3 times and repeats this over and over. Down on the lower board, the one that connects to all of the audio / video outputs also has two micro leds, the first comes on green when the other two do, the other flashes for the same 5 seconds until the main power shuts down.

DK

There are several possibilities. It's been about a year since I tackled one of these. It had a back-level firmware and the bulged caps. It would flash an error 11. I replaced the caps and updated the firmware. This COULD be reporting the wrong error. Or there could be a problem with the 8.6 V supply, or the load on the supply.

One of the easiest tests is to check the output voltages of the power supply. Start with the outputs to the SSB. The 8.6 volt supply is on pin 3 of the 11 pin connector.

PlainBill

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

I removed the plugs from the X and Y boards and the TV no longer shut off. I plugged the X board in and it didn't shut off. I plugged the Y board in and it did exactly what it was doing before, power on for a few seconds, shut off, repeating 7 red blinks on the front indicator. So, I presume this means it is either the Y board or the circuit in the power supply board that supplies the Y board. I will be checking the voltages and will report back. I downloaded the manual that was linked but I could only get it to come up in Spanish and me no hablo espanol. Thanks for any help and advice.

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Update: I checked the voltage test points on the main board and found the following. Any time that the Y sus board is plugged in the system exhibits the shutdown and 7 red blinks I mentioned before. The riser card on the power board blinks 3 tmes in succession repeatedly and the other LED's go off after about 8 seconds. Most of the voltage points go to 0. When I unplug the Y sus board then everything appears to be normal other than no picture. There is no error code, no 3 blinking green led's. The Ve, Va, Vs, Vscan, Vset, 12V, 5V, 3.3V all measure out within a reasonable measure of the voltages printed on the sticker in the tv case.

I don't know much about these Y sus boards but this leads me to conclude that the Y board is the most likely culprit, probably a shorted component. Upon examination, all caps on that board look fine and there is no visible burned marks or charring of any type. I am looking for advice on what steps to take next to validate my assumption or continue the troubleshooting.

Thanks.
DK

[PlainBill]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Update: I checked the voltage test points on the main board and found the following. Any time that the Y sus board is plugged in the system exhibits the shutdown and 7 red blinks I mentioned before. The riser card on the power board blinks 3 tmes in succession repeatedly and the other LED's go off after about 8 seconds. Most of the voltage points go to 0. When I unplug the Y sus board then everything appears to be normal other than no picture. There is no error code, no 3 blinking green led's. The Ve, Va, Vs, Vscan, Vset, 12V, 5V, 3.3V all measure out within a reasonable measure of the voltages printed on the sticker in the tv case.

I don't know much about these Y sus boards but this leads me to conclude that the Y board is the most likely culprit, probably a shorted component. Upon examination, all caps on that board look fine and there is no visible burned marks or charring of any type. I am looking for advice on what steps to take next to validate my assumption or continue the troubleshooting.

Thanks.
DK

If the numbers on the Y-Sustain and Y buffers are LJ92-01200A, LJ92-01202A and LJ92-01203A, you have a common problem. I'd suggest reading http://blog.coppelltvrepair.com/ for a discussion of the problems and the (expensive) solution.

PlainBill

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Ouch! I don't like what I read, is there a second opinion that is more favorable? LOL, just kidding. Of course mine are the 120x boards. That pretty much nails my situation so it appears that I am looking at repairing all three boards at a minimum if I want to get this thing running again. I have long been telling people not to pay any more than scrap value for used plasmas on CL because they have either been repaired or will need to be repaired. Now I understand the supporting evidence underlying what I knew intuitively. Although I can now tell people that it will likely need repaired again EVEN IF it has already been repaired. The two 3300uF bad caps replacement isn't necessarily the end-all fix even if it gets the tv up and running again short term.

I'd be willing to do the repairs if I knew which IC's to replace but maybe it's time to just sell it off to the scavengers on CL in its current state. Has anyone ever come across more info on the details of the board repairs so I have a better understanding of the extent of what I am contemplating here?

PlainBill, thanks for the info and link, at least that Coppell blog provides a seemingly fair and objective viewpoint from an apparent expert without resorting to scare tactics.

DaKid

[PlainBill]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Ouch! I don't like what I read, is there a second opinion that is more favorable? LOL, just kidding. Of course mine are the 120x boards. That pretty much nails my situation so it appears that I am looking at repairing all three boards at a minimum if I want to get this thing running again. I have long been telling people not to pay any more than scrap value for used plasmas on CL because they have either been repaired or will need to be repaired. Now I understand the supporting evidence underlying what I knew intuitively. Although I can now tell people that it will likely need repaired again EVEN IF it has already been repaired. The two 3300uF bad caps replacement isn't necessarily the end-all fix even if it gets the tv up and running again short term.

I'd be willing to do the repairs if I knew which IC's to replace but maybe it's time to just sell it off to the scavengers on CL in its current state. Has anyone ever come across more info on the details of the board repairs so I have a better understanding of the extent of what I am contemplating here?

PlainBill, thanks for the info and link, at least that Coppell blog provides a seemingly fair and objective viewpoint from an apparent expert without resorting to scare tactics.

DaKid

Coppell TV's blog indicates that EVERY buffer chip should be replaced. His theory is the silicon sealant around the leads breaks down, triggering the failure. These are SN755867 / SN755870 and cost $13 each.

On the Y-sustain there are a set of IXTA36N30P transistors under a heat sink. It is possible to isolate the one which has failed and replace only that one. They run $7 each. The problem is these are the TO-263 package, so it required pretty good rework equipment to remove them.

PlainBill

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

How would I best go about determining which of the 36N30P transistors is bad?

Thanks for all of your advice and help.
DK

Coppell TV's blog indicates that EVERY buffer chip should be replaced. His theory is the silicon sealant around the leads breaks down, triggering the failure. These are SN755867 / SN755870 and cost $13 each.

On the Y-sustain there are a set of IXTA36N30P transistors under a heat sink. It is possible to isolate the one which has failed and replace only that one. They run $7 each. The problem is these are the TO-263 package, so it required pretty good rework equipment to remove them.

PlainBill

[PlainBill]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

How would I best go about determining which of the 36N30P transistors is bad?

Thanks for all of your advice and help.
DK

That was covered in another section of the Coppell TV blog.

It's a lot easier if you pull the heat sink over the transistors.

PlainBill

[retiredcaps]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

How would I best go about determining which of the 36N30P transistors is bad?

I don't know what this board looks like or how easy it is to access the transistors, but the datasheet at



shows them as 3 pin. So with power off and TV unplugged, measure "in circuit" the ohms between S-D, S-G, and G-D. Any reading less than 30 ohms suggests a possible short.

[DakotaKid]

Re: Philips 42 Plasma 7 blinks 42PF7220A /37

Makes perfect sense, I will test them out and see what I find.

Thanks.