TCP55ST30 SU/SD board test needed (7 blinks)

[Truncatedhose]

I have the service manual for this TV, but not the training manual and the S/M doesn't show how to isolate or test the SU/SD boards. Does anyone have the procedure or the training manual? I have training manuals for other models, but I don't think I can use the same procedure. Also, can you test Panasonic buffers the same as any other buffer with the standard buffer IC ground test?

Thanks!

[tvtimmy]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

You should be able to remove the 4 ground screws from the SC board and the 3 connectors to it and then put your neg.lead on one of them floating grounds and go across the pins on the connectors and listen for the beeps. You will have to remove each ribbon from the panel to check both sides and the cable from upper to lower to get accurate test results

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Ditto. That's what I'd do.lift the latches and slide along each and every pin.. looking for nothing shorted. Generally this will do and saves the drama of reseating panel ribbons

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

https://www.badcaps.net/forum/attach...7&d=1474538736

I had a look for one I'd uploaded previously in my profile. I've uploaded 1245 attachments. I'd hate to think how many of the same I've done over and over.

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Ditto. That's what I'd do.lift the latches and slide along each and every pin.. looking for nothing shorted. Generally this will do and saves the drama of reseating panel ribbons

Okay, thank you, but I'm confused. TVtimmy says I'll have to remove each ribbon from the panel, but you say I don't? Did I miss something? I test from a floating ground point to the connectors going to the SC (after the ground screws are pulled and the connectors lifted), or do I have to test to the panel ribbon connectors with the ribbon cables pulled? Or both?

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Okay, thank you, but I'm confused. TVtimmy says I'll have to remove each ribbon from the panel, but you say I don't? Did I miss something? I test from a floating ground point to the connectors going to the SC (after the ground screws are pulled and the connectors lifted), or do I have to test to the panel ribbon connectors with the ribbon cables pulled? Or both?

Difference of opinion, he's 100% right for accuracy but I find if the ICs have shorted it's usually the whole buffer IC so there'll be shorts on both sides of the pins. You only have to find 1 short so chances of having all shorts on the outside pins and none on the inside would be slim.

alternative would be resistance check at Vfo, VF-5v V_scn pins on the sd/su with respect to Vfg. Vfo often will be short if the board is bad.

you'll need the service manual to identify the pins, block diagram is usually a clear one to look at.

The guide has another way suggested I've never tried but if you're good at pulling ribbons out and getting them reseated correctly with no issues then go for it and pull them out.

Just I read a lot of times people have trouble getting them in right

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Okay, see the screenshot below of the training manual (thank you so much for providing it btw!). I followed the steps for troubleshooting 7 blinks and since the TV doesn't stay on with a blank picture when I unplug the plugs that it directs me to, I don't even go down the path of testing or isolating the SU/SD. Instead, it wants me to see if VSUS comes up and it doesn't (strangely, when I 1st tested it, it came up, but immediately was dropping to zero, and the 2nd time, it didn't come up at all.), Then it says, as you can see, to replace the P board.

My question is: does this make sense and/or should I test the SU/SD anyway?

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Okay, see the screenshot below of the training manual (thank you so much for providing it btw!). I followed the steps for troubleshooting 7 blinks and since the TV doesn't stay on with a blank picture when I unplug the plugs that it directs me to, I don't even go down the path of testing or isolating the SU/SD. Instead, it wants me to see if VSUS comes up and it doesn't (strangely, when I 1st tested it, it came up, but immediately was dropping to zero, and the 2nd time, it didn't come up at all.), Then it says, as you can see, to replace the P board.

My question is: does this make sense and/or should I test the SU/SD anyway?

yeah, ok I see where you're at. I thought you'd already figured bad SC and just wanted to do the SD/SU test.

Sounds like SC2 could be short circuit. This generation major cause is SC failure.

Here's some options.
1. yes , do the SD ,SU checks, need too regardless.

2. you could check the resistance across SC2, if it's shorted or low ohms it's cactus.
3. you could check all 30F131 and RJP30H2 transistors and again check if shorted across any 2 legs, chances are they will be Q401-403 and Q421-423 are the most common. You just place the probes one on each

4. isolate the sd/su by removing 4 Vfg bolts and the 3 white connectors, on the SC jumper the 2 pins at SC50, now turn it on. If it turns on with no display i.e. no shutdown and error blinks then the SC is good and most likely sd/su.

If you find shorts at 2 or 3 don't bother with 4

I would not go down the A or P board path at this point, that's less likely.

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

yeah, ok I see where you're at. I thought you'd already figured bad SC and just wanted to do the SD/SU test.

Sounds like SC2 could be short circuit. This generation major cause is SC failure.

Here's some options.
1. yes , do the SD ,SU checks, need too regardless.

2. you could check the resistance across SC2, if it's shorted or low ohms it's cactus.
3. you could check all 30F131 and RJP30H2 transistors and again check if shorted across any 2 legs, chances are they will be Q401-403 and Q421-423 are the most common. You just place the probes one on each

4. isolate the sd/su by removing 4 Vfg bolts and the 3 white connectors, on the SC jumper the 2 pins at SC50, now turn it on. If it turns on with no display i.e. no shutdown and error blinks then the SC is good and most likely sd/su.

If you find shorts at 2 or 3 don't bother with 4

I would not go down the A or P board path at this point, that's less likely.

Okay, yeah I checked SC2 right away when starting on this TV; it's not shorted. Do you think I should still check all the parts on the SC board? And for your step #1, can you spell out what you mean by these tests in detail? Sorry, but I want to be clear on the best way to test the SU/SD. Yes, then I will also isolate them, unless you think isolating them is enough to determine if they are the problem? And then if they're not, the A or P board might be where the issue is as the flow chart indicates?

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Okay, yeah I checked SC2 right away when starting on this TV; it's not shorted. Do you think I should still check all the parts on the SC board? And for your step #1, can you spell out what you mean by these tests in detail? Sorry, but I want to be clear on the best way to test the SU/SD. Yes, then I will also isolate them, unless you think isolating them is enough to determine if they are the problem? And then if they're not, the A or P board might be where the issue is as the flow chart indicates?

I just realised something. Your 55ST30 is different to ours and uses TNPA5351 SC board, is that right?

So some of my info is off slightly especially what transistors may fail on the SC.

Coppell TV has done a 3 part video. Part 2 shows him testing the buffers as I suggested leaving them in , lifting the latch and sliding the pins on the back.

Rather than risking confusing this more for you, I'd have a look at these videos and see what results you can achieve.

I don't know that exact revision of board But I've done several 50U30 TVs here with 5351 version boards and it's 50/50 for 7 blinks, either blown SC or I've found the remainder were shorted SU normally the top ICs.


https://www.youtube.com/watch?v=gSDDenXeRm4

https://www.youtube.com/watch?v=jFv7jmDUBm8

https://www.youtube.com/watch?v=q1GpwoI1py8

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Okay, so I just did the isolation procedure for both SU/SD simultaneously and the TV still has the 7 blink error code. Before proceeding with a P board, can you confirm what you think I should do next? Do you think I should still check parts on the SC even with SC20 is not shorted? (and following the chart, I guess it's saying SC is good)...but I'm willing to verify, just let me know, thanks!

[Moreno83]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

On the 42ST30 the power supply also fails. I repaired a 50ST30 before , cant remember what powersupply this tv has though....

7 blinks is definately SC board if you isolated the SU/SD boards.

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

This is getting confusing.

"isolation procedure for both SU/SD simultaneously "

so is this disconnecting the 3 connectors , 2 on the SD, 1 on the S, removing the 4 Vfg bolts fromSD/SU, jumping the pins at SC50 and 7 blink error?

If so SC is bad, then just check the SD/S board output pins for short to Vfg like you see in the video.

If they're good then focus on the SC and start looking for shorted transistors

[tvtimmy]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

I would always check everything on SC board. I had a few that showed no short but had shorted IGBTs on it.

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

and another video. He gets a bad SU top buffer ICs

https://www.youtube.com/watch?v=_oX8hMcXjWg

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

I just realised something. Your 55ST30 is different to ours and uses TNPA5351 SC board, is that right?

So some of my info is off slightly especially what transistors may fail on the SC.

Coppell TV has done a 3 part video. Part 2 shows him testing the buffers as I suggested leaving them in , lifting the latch and sliding the pins on the back.

Rather than risking confusing this more for you, I'd have a look at these videos and see what results you can achieve.

I don't know that exact revision of board But I've done several 50U30 TVs here with 5351 version boards and it's 50/50 for 7 blinks, either blown SC or I've found the remainder were shorted SU normally the top ICs.


https://www.youtube.com/watch?v=gSDDenXeRm4

https://www.youtube.com/watch?v=jFv7jmDUBm8

https://www.youtube.com/watch?v=q1GpwoI1py8

Sorry, my reply after this was made before I saw that you had posted the above message. I will check those videos.

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

This is getting confusing.

"isolation procedure for both SU/SD simultaneously "

so is this disconnecting the 3 connectors , 2 on the SD, 1 on the S, removing the 4 Vfg bolts fromSD/SU, jumping the pins at SC50 and 7 blink error?

If so SC is bad, then just check the SD/S board output pins for short to Vfg like you see in the video.

If they're good then focus on the SC and start looking for shorted transistors

Yes, that's what it is. Well, I will watch those videos and check the components on the SC and get back to you. It's funny though, the training manual and service manual don't list the SC board under the 7 blink error code. They only list the SU and SD. They also don't list the P or A board under the error code chart, yet they do say the P or A board in the troubleshooting flowchart that I took the screenshot of to show you.

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Oh and yes it is a TNPA5351.

[tw2005]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Yes, that's what it is. Well, I will watch those videos and check the components on the SC and get back to you. It's funny though, the training manual and service manual don't list the SC board under the 7 blink error code. They only list the SU and SD. They also don't list the P or A board under the error code chart, yet they do say the P or A board in the troubleshooting flowchart that I took the screenshot of to show you.

Really? Depends where you read.

SC listed 1st followed by SD/SU, Panel and A board.

The guides are not always without fault or omission.

[Truncatedhose]

Re: TCP55ST30 SU/SD board test needed (7 blinks)

Really? Depends where you read.

SC listed 1st followed by SD/SU, Panel and A board.

The guides are not always without fault or omission.

Ahhhh! Thank you, I don't remember where I read it, but thank you.