Help-Panasonic TC-P50VT25 switches off, 11 blinks, tried cleaning fans already

AnnyC

Novice Member
Help-Panasonic TC-P50VT25 switches off, 11 blinks, tried cleaning fans already.

Our old plasma TV has a beautiful picture, but has started to switch itself off after a few seconds. I left it unplugged for a day (that fixed the problem last time). When I plugged it back in it turned on briefly, then switched off. Red light blinks 11 times. So we took off the back and carefully cleaned all the dust off the fans. Put it back, turned it on, and same thing again: turned on briefly, turned itself off, 11 blinks.

QUESTION: Is there any point to taking it somewhere to get fixed, or is there a part we could buy on eBay and replace on it? What part (power supply)? Or should we just buy a new set? I hate to get rid of a TV with such a beautiful picture if it is possible to fix it instead.

Your thoughts welcome, including what to replace it with. We watch TV and movies on cable and Roku, little sports, no gaming. Picture quality, reliability, value are the priorities. Same size is fine, or next size larger. OLED?
 

mikej

Well-known Member
A quick search for the technical guide for your TV gave this result. The 'Power LED Error Code' chart (slide 78) suggests that the 11 blink error code is a 'Fan SOS' and check points are the fans, the A board and the connection and cables between them.

A more detailed explanation of the 11 blink error code is on slides 86 & 87 and includes the following...

"The fan drive circuit is located on the A board. To control the speed of the fan, a control voltage from the microprocessor(IC1100) is applied to IC5740. If any of the fans is removed or becomes defective, a high is output at the corresponding pin (pin3, 9, or 12) of the fan connector (A30) to forward bias the inline diode. The DC output of the diode is provided to pin 61 of IC1100 to trigger the SOS condition."

So... the fault might be something as simple as a defective fan and if this was the case, then it could be a relatively cheap fix as plasma fans tend to be similar to those found in a PC. A faulty 'A board' is a different proposition though, as parts for plasmas of that age are becoming scarce and second-hand / reconditioned parts or a board repair service are likely to be the only options, as new parts will no longer be available.

Presumably, removing / isolating and testing each fan to see if any are defective would be the first thing to try but this should only be done by a TV engineer or at least someone fully competent with working with electronics, as charge can be retained in certain TV components long after a TV is switched off (voltages as high as 380V, apparently !), which makes them potentially very dangerous to work on without the right knowledge.

Are you able to see the fans through the vents when the back cover is on ? Try shining a torch on the vent holes, turning the TV on and seeing if the fan spins up. Doing this with each fan in turn might possibly identify one that isn't working.

The other service manual one I was able to track down was this one - it's nowhere near as comprehensive as the other one, but it does have a parts list and schematics for the A board which may be useful for a TV engineer.
 

AnnyC

Novice Member
A quick search for the technical guide for your TV gave this result. The 'Power LED Error Code' chart (slide 78) suggests that the 11 blink error code is a 'Fan SOS' and check points are the fans, the A board and the connection and cables between them.

A more detailed explanation of the 11 blink error code is on slides 86 & 87 and includes the following...

"The fan drive circuit is located on the A board. To control the speed of the fan, a control voltage from the microprocessor(IC1100) is applied to IC5740. If any of the fans is removed or becomes defective, a high is output at the corresponding pin (pin3, 9, or 12) of the fan connector (A30) to forward bias the inline diode. The DC output of the diode is provided to pin 61 of IC1100 to trigger the SOS condition."

So... the fault might be something as simple as a defective fan and if this was the case, then it could be a relatively cheap fix as plasma fans tend to be similar to those found in a PC. A faulty 'A board' is a different proposition though, as parts for plasmas of that age are becoming scarce and second-hand / reconditioned parts or a board repair service are likely to be the only options, as new parts will no longer be available.

Presumably, removing / isolating and testing each fan to see if any are defective would be the first thing to try but this should only be done by a TV engineer or at least someone fully competent with working with electronics, as charge can be retained in certain TV components long after a TV is switched off (voltages as high as 380V, apparently !), which makes them potentially very dangerous to work on without the right knowledge.

Are you able to see the fans through the vents when the back cover is on ? Try shining a torch on the vent holes, turning the TV on and seeing if the fan spins up. Doing this with each fan in turn might possibly identify one that isn't working.

The other service manual one I was able to track down was this one - it's nowhere near as comprehensive as the other one, but it does have a parts list and schematics for the A board which may be useful for a TV engineer.
Thank you! We took the back off and it looks like one of the fans isn't working right (maybe a flat space on a bearing). My husband tried changing the leads to the fans around and it was definitely the fan, not the connection. So he's ordered another fan (quite a hunt to find one). We didn't know about the retained charge issue, guess we were lucky! Altho the set had been unplugged for awhile. Really appreciate your research. Once we get the fan we'll see if the TV works. He also ordered a power supply board (is that the right term) before we realized it was the fan, so we'll have that too. The TV's display is still fine, and I hate the idea of discarding it!
 

mikej

Well-known Member
That's great news - a fan replacement must be one of the cheapest, easiest faults to repair on a plasma. Fingers crossed that's all that's wrong with it :)

Yes - the insides of a TV can be very dangerous to the unwary, so please appreciate that certain components can still retain a potentially lethal charge even after leaving the TV unplugged for a while. You mustn't touch any of the boards and components unless you really know what you are doing.
 

AnnyC

Novice Member
That's great news - a fan replacement must be one of the cheapest, easiest faults to repair on a plasma. Fingers crossed that's all that's wrong with it :)

Yes - the insides of a TV can be very dangerous to the unwary, so please appreciate that certain components can still retain a potentially lethal charge even after leaving the TV unplugged for a while. You mustn't touch any of the boards and components unless you really know what you are doing.
Fingers crossed here too. Will be extra careful and warn husband too. I suspect he knows but always good to remind.
 

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