Yet Another TC-P55GT30 7 Blinking Light Error

[kazu]

Hey everyone! Just picked this TV up for $25 off of Craigslist to fix and give to my fiance in her new apartment.
I've looked at a lot of other threads regarding the blinking light errors but most of what I found were people getting upset and giving up. I'd like to really fix this thing.

As I said, the TV gives me a 7 blinking light error when I hit the power button. I've removed the white connectors (can't think of the names of them since I'm not in front of the TV right now) that connect the SD and SU boards to the SC board. When I hit the power button with these connectors disconnected it gives me 8 blinking lights. I think this means that it is the SC board but I'm not positive.

I have not tested for any shorts yet as I do not have a multimeter and I'm not very experienced with them. Up until this point, I've mostly just replaced boards without testing a got lucky on some TVs.

I am getting a multimeter tonight to test for shorts. I'd appreciate any help to isolate and identify which board is faulty so I can either buy a new one or send it off for repair - which seems to be my only option since these parts don't seem available anymore.

[Sevenqi]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Please check if the power cable connector on the SC board is shorted.
when you disconnect the SC board from power supply, you may need to disconnect the cable from the digital board to the SC board.

[kazu]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Tested everything I could with a multimeter and my dad's help since I don't know how to configure a multimeter myself. We were reading for Ohms and everything that we measured was an open circuit, as my dad said, and was not shorted - all the pins we tested read 1 on the multimeter with a few exceptions.

The few exceptions were one corresponding pin on each ribbon connector on the SU and SD boards. The other exception was one pin on the white connector going from the SC board to (I think) the SU board.

This leads me to believe that the SC board is at fault. Would I be correct?

@Sevenqi: I completely forgot to check the power cable. The TV isn't with me now so I'll have to check it in a few days. Which "digital board" are you referring to?

I made an imgur album to help explain and show where I tested.

[tw2005]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

the ribbon that connects the sd and su at sd11/su11 is missing , do you have it?

The gummy stuff is conformal coating to protect the board from the elements and reduce oxidizing.

7 blinks traditionally can be sc,sd or su . Could be one board or any combination up to all three.

One way to eliminate whether this is SC or not is to disconnect the sd & su boards at the SC(3 connectors), then remove the 4 grounding bolts for the sd/su ( 2 each and these bolt into the SC.

Now there is a small 2 pin connector SC50, if you have a small alligator clip you may be able to get the nose of it across those pins to short them together.

Power the TV on. If it turns on and no 7 blink then the SC is good and you have shorted SD or Su or both.

If it 7 blinks then bad SC and it's common for the 30F131 and/or RJP30H2 SMD transistors to short out. But you will still have to check the SD/SU boards.

I have looked at 2 x 50U30, 1 locked out solid LED, that was shorted Vsus at the SC2, the other is a 7 blinker and that is shorted SU board.

50ST30 , 7 blinker, bad SC board
50GT30, 7 blinker, bad SC

Both of those also went 8 blink after the SC was fixed and that was the SS boards o both having a shorted RCJ330N25 FET shorted

[kazu]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

the ribbon that connects the sd and su at sd11/su11 is missing , do you have it?

The gummy stuff is conformal coating to protect the board from the elements and reduce oxidizing.

7 blinks traditionally can be sc,sd or su . Could be one board or any combination up to all three.

One way to eliminate whether this is SC or not is to disconnect the sd & su boards at the SC(3 connectors), then remove the 4 grounding bolts for the sd/su ( 2 each and these bolt into the SC.

Now there is a small 2 pin connector SC50, if you have a small alligator clip you may be able to get the nose of it across those pins to short them together.

Power the TV on. If it turns on and no 7 blink then the SC is good and you have shorted SD or Su or both.

If it 7 blinks then bad SC and it's common for the 30F131 and/or RJP30H2 SMD transistors to short out. But you will still have to check the SD/SU boards.

I have looked at 2 x 50U30, 1 locked out solid LED, that was shorted Vsus at the SC2, the other is a 7 blinker and that is shorted SU board.

50ST30 , 7 blinker, bad SC board
50GT30, 7 blinker, bad SC

Both of those also went 8 blink after the SC was fixed and that was the SS boards o both having a shorted RCJ330N25 FET shorted

I do have the ribbon cable. Simply took it off to make it easier testing. Now are you suggesting that I short SC50? What would the purpose be?

[tw2005]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

have a read.

If you isolate the sd/su then the TV will 7 blink, however the purpose of sc50 shorted is to complete the cct that detects either the sd or su being removed and shutting down.

If you follow the procedure as per the guide(make sure those Vfg bolts are out on the sd/su)

then it is a quick way to find out if the SC is causing 7 blink.

If it passes focus on the sd/su tests and finding the bad buffer board.

If it fails then you need a SC and you stil have to check those buffers.

[Elevatorguy4]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Good info here. I'm having a similar problem. Going to start a new thread, but I needed to reply here to get a post so I can start a new thread as a new member. Thanks.

[Elevatorguy4]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Well that didn't work. I thought I needed a reply post in order to start my first new thread but it's still restricting me. I guess I'll jump on here. I have a P55GT30 that got the 7 blinks of death the other day. I've read a bunch and here's what I've come up with. The SC board,with the 3 plugs from the SU a d SD boards as well as the white ribbon cable and tan/white power lead unplugged, is reading a dead short between the pins at SC2 on my meter. I understand that this indicates a bad SC board. On the SU and SD boards, with the 3 connectors unplugged that go into SC, I set my meter on ohms and read with one lead on a screw from the buffer boards to SC and with the other lead I probed the 12 (4 on each of the 3 connectors) pins onto the boards. 8 of 9 of them read OL, or infinite ohms and 3 or 4 read around 8 M ohms or higher. Am I correct that these buffer boards are good? I know the easiest and safest way is to just replace all boards, but I don't want to waste money if I don't have to. Is there anything else I should check? If all I need to do is replace the SC board and have a full and long lasting repair then that's all I will do. I just want to fix it once and fix it right. I will also note that recently on a few occasions there was a weird fuzzy purple tint on some light colored backgrounds. This issue would come and go. Thanks in advance for any and all replies and help. I've learned a ton here over the past couple of days.

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Usually there are 2 scenario's with a 7 blinker. SC board or SU/SD die and short the SC board.
Remove the buffer boards from the TV and make sure that they don't touch the SC board. Use a harddisk jumper and short the pins on SC50 connector. Its located top left on the board. Turn on the tv , still 7 blinks then SC board is bad.

There are 6 known fets on the SC board that usually fail and they are located above and next to the black capacitors. Q401 , 402 , 403 , 421 , 422 , 423. More parts will read short but thats because these 6 are shorted.
Measure the outer pins in diode mode , if they give a beep then all 6 are bad. Those are the only ones you need to replace and if they beep you got a 95% chance the buffers are still good.

If these fets are not shorted then measure the fets and diodes on top of the board , they go bad when the buffers go bad.

When you order parts for the repair , make sure you get ORIGINAL parts. We use FGD4536TM and digikey/RS has them.

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

The colour problem you mentioned is because of the loose screws. Check it out , im sure some screws are not tightened.

I just repaired a 50GT30 and the owner said the same thing. Weird colour and it turned off.

[Elevatorguy4]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Thank you for the reply Moreno83. Was the way I tested the buffer boards not correct? As I stated, I read somewhere on this forum to put my meter on continuity, ground one probe at a screw from the SU or SD board to the SC board and then test each of the 12 pins under the connectors on the SU and SD boards looking for low resistance readings. I'm hoping someone can confirm if this is an accurate way or not to prove these buffer boards. Like I said I want to fix it right the first time but don't want to replace any parts unnecessarily. Thanks again for the shared knowledge.

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Remove the buffer boards from the tv. Meter in continuity mode , Put the black prope on ground ( Screw hole ) and slide the red prope against the copper pins under the tabs.

https://www.youtube.com/watch?v=51SZsfH60EY

[Elevatorguy4]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Thanks again for the help Moreno83, but I am a little confused. Is the way I tested mine as I described going from ground to each of the 12 (3 x 4) pins on the connectors that go from the buffers to the SC not a good test? I read somewhere here to do that. Your video suggest probing onto the connectors on the opposite side that attach to the screen lines. Can you please clarify this for me? Thanks

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

No problem!

I dont know if thats a correct way to measure , i never use that method.

Just do it as in the video , its the easiest and most accurate way as those copper lines are directly connected to the buffers and the buffer chips fail. Buffers must be removed from the panel if you test them!!

Dont make it to hard for yourself and test the parts as i said. If the 6 fets are shorted then SC board is dead. If they are not shorted then measure the fets and diodes on top of the sc board. If these are shorted then one or both buffer boards are dead.

[tvtimmy]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

The buffer boards HAVE to be isolated, no screws to the SC board. Take out the 4 screws and unplug the 3 white connectors. You can slide a piece of paper in between the buffers and the SC to insure total isolation. Then test as mentioned.

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

dont forget to get original parts , otherwise it will take a few tries to fix the board.

[Elevatorguy4]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

I got my testing method here https://m.youtube.com/watch?v=MX7e9aSlbJQ for the buffer boards. Is this not an accurate way to determine if they're bad? Mine tested good with this method but the SC board tested bad. Thanks again for the help.

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Ok , replace the 6 fets and get lockwasher screws in the same size. Dont forget to solder the backside of the board. ( ground ).

[Elevatorguy4]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

Table Moreno83. I'm actually going to exchange the SC board for a rebuilt locally. Does the testing method in the video make sense to you? If I do in fact have a bad SU and/or SD board, will it cause damage to the new SC when I put it in? Again I appreciate all the help.

[Moreno83]

Re: Yet Another TC-P55GT30 7 Blinking Light Error

hmm it makes sense but his boards are still connected to the SC board.

Best way is to remove both buffer boards from the panel completely and test them as in the video i posted.
Ps , don't pay to much. The parts are very cheap.