Calling any TV engineers

[kegnkiwi]

Hi guys

I've got a spare panasonic th37px70b thats has a fault that I need help resolving. After switching the tv on anytime between 2 mins and 5 mins the tv puts itself into standby and flash's a series of 7 flash's then stops and then flashs a constant 8 then space then 8 flash's. I took the power supply board of and found a dry joint on a large diode I desoldered the diode and resoldered it that but it did not resolve the issue. I can buy a power supply kit on ebay for £33.00 but I don't think its the power supply as it powers up. From what I can find on the net if could be the ysus board.

Y-SUS BOARD PANASONIC TH-37PX70B 37" LCD TV TNPA4182 1 SC | eBay

Can one advise me if I'm looking in the right direction.

Many thanks.

 

[danforth]

Hi guys

I've got a spare panasonic th37px70b thats has a fault that I need help resolving. After switching the tv on anytime between 2 mins and 5 mins the tv puts itself into standby and flash's a series of 7 flash's then stops and then flashs a constant 8 then space then 8 flash's. I took the power supply board of and found a dry joint on a large diode I desoldered the diode and resoldered it that but it did not resolve the issue. I can buy a power supply kit on ebay for £33.00 but I don't think its the power supply as it powers up. From what I can find on the net if could be the ysus board.

Y-SUS BOARD PANASONIC TH-37PX70B 37" LCD TV TNPA4182 1 SC | eBay


Can one advise me if I'm looking in the right direction.

Many thanks.

Before you start looking in more complex areas, consider PSU instability. Don't buy a new PSU yet, but check the capacitors on it.

Post a pic, if you're not sure what to look for.

 

[kegnkiwi]

All the caps look good no bulging or leakage marks on the board, I'll whip the board back out tomorrow and take some photo's, doing a bit of googling there little bits of info out there but nothing concrete.

 

[danforth]

All the caps look good no bulging or leakage marks on the board, I'll whip the board back out tomorrow and take some photo's, doing a bit of googling there little bits of info out there but nothing concrete.

Fair enough, just making sure the basics were covered, not really much point in the pictures then.

You can do an ESR check on the caps to be sure, but apart from that, my experience of modern TVs is limited, to put it mildly.

 

[kegnkiwi]

Just for reference here are 4 picture of the board I just wipped out of the tv, you can see some heat marks on the rear of the board where I desoldered the diode identified as discharge. It needed to get hot to melt the solder one side melted easily but the other took so doing.

 

[danforth]

Just for reference here are 4 picture of the board I just wipped out of the tv, you can see some heat marks on the rear of the board where I desoldered the diode identified as discharge. It needed to get hot to melt the solder one side melted easily but the other took so doing.

Big one on the RHS looks iffy! (swollen)

 

[parker13]

all caps look ok, but it's a myth they need to swollen and vented to be faulty, unlikely to be a cap though, will report back.

 

[danforth]

all caps look ok, but it's a myth they need to swollen and vented to be faulty, unlikely to be a cap though, will report back.

Agreed, that's why I said an ESR check, but the big one on the RHS looks swollen anyway.

As for the rest, I defer to greater knowledge.

 

[parker13]

No probs danforth, caps don't usually fail once they have started up as it were, they can be low in uf and once the circuit has been trying to run and the cap has warmed up the uf usually increases enough, in the early days for the cap to do it's job, kegnkiwi, are you sure that's the LED pattern ?

 

[kegnkiwi]

Hi parker,

Ok put board back in the tv tonight and fired it up, fired it up without an aerial connected and turned it to an anologue channel with just snow on the screen left it running for 30 mins all ok. Turned tv off put back back on and move it to an aerial point plugged aerial in and turned it to a digital channel and 10 mins later its off again. Go the other half to check to led patten and sure enough its actually 8 flash's. Any ideas mate.

 

[chookey]

Dry joints on Q6041 and Q6042 on the Z SUS board has been known to flash the error code 8 on this model. Symptoms were intermittent sound and picture.
Could easily be seen as having switched to standby.

 

[kegnkiwi]

Dry joints on Q041 and Q042 on the Z SUS board has been known to flash the error code 8 on this model. Symptoms were intermittent sound and picture.
Could easily be seen as having switched to standby.

Do you think that these q041 and q042 (transistors i believe) could have anything to do with the freeview tuner circuit, i have just tested again that when tv is on in analogue state the tv will stop on no probs other that 30 minuets when it puts itself in to standby due to lack on signal but add the aerial and put in freeview mode and tv shows fault after less than 3-4 mins.

 

[chookey]

They have no relation to the tuner mate, they form part of the energy recovery circuit which in fault state will flash the 8 light sos code. Don't have time to delve deeper for you at the moment, bedtime, got an early start tomorrow.
The Z SUS board is known as the SS board in this model, lives on the far right of your tv.

 

[chookey]

Don't dwell too much on the fact that the problem doesn't appear to exist when switched to analogue kegnkiwi. There is no audio or video processing taking place.
Its' a bit like saying your car cuts' out when you rev it up but ok on tick over, the fault must be with the throttle.

Try the transistors mate but after that, if no good I would suggest having an engineer take a look. The internet is ok for the faulty capacitor brigade but your fault is beyond that.

 

[kegnkiwi]

hi mate, I'll pull the board out over the weekend and have a look at the transistors. Its a spare tv so in no rush and don't want to spend loads on an engineer like to try and fix myself.

 

[kegnkiwi]

Don't dwell too much on the fact that the problem doesn't appear to exist when switched to analogue kegnkiwi. There is no audio or video processing taking place.
Its' a bit like saying your car cuts' out when you rev it up but ok on tick over, the fault must be with the throttle.

Try the transistors mate but after that, if no good I would suggest having an engineer take a look. The internet is ok for the faulty capacitor brigade but your fault is beyond that.

Dropped the ysus board out last night and took a look at the transistors but there where no obvious signs of anything a miss. As I have nothing to loose took a medium sized soldering iron to the pins which I must say have very little solder on them and mixed it with new solder, Put the board back in the tv and up running in short while. Had the tv running for 2.5 hours last night not a flicker, so it looks like it we have it sorted. Going to test again tonight and I will let you know. Thank you.