panasonic th-50u30a no blink code

[tw2005]

Re: panasonic th-50u30a no blink code

Yeah I'm not following the logic. I see you show no voltage present at the bridge. But 240v is lurking nearby around the relays. You show 15v with arrows pointing at the relay so I assume this would mean it's energised ? If so the 240v will be at the bridge if not then either the relays are not latched, or the contacts are burnt out.

Regardless whether the bridge is working or not unless it is dead short and you have said it checks ok then 240v has to be there and after rectified should be 1.414 x input = 325 - 340v.

My understanding is the A board sends the command to latch the relays.

[tw2005]

Re: panasonic th-50u30a no blink code

So I found a schematic for MPF6907 which looks very similar, and so with the 15V you found at the relays it would appear that is constant but the gnd is switched.

So signals from IC601 relay_main_on, relay_rush_on turn on Q608,609 , that grounds relay_main, relay_rush, the relays close , neutral is feed straight to the rectifier, Live is switched by the relays.

Hopefully this schematic may just help.
Also looking at it the in-rush relay would need to be closed first then the main relay otherwise the 240V will get drawn through the 5W thermal resistor .

[tw2005]

Re: panasonic th-50u30a no blink code

Reading this all over again, you reported 3.3v and 1.2V STB at ic5000, that powers the ic8000 which sends the 3.2v to P6 pin 7 which goes to the MPU and latches the relays and turns the F15V on.

I think if you don't see that 3.2v trigger at pin 7 when the tv is plugged in and the master switch in the on position(it's only there maybe 30secs they say 15sec seems longer to me) then that's an issue which stems from the A board assuming the 3.3 and 1.2v are being applied to ic8000.

[attainteddragon]

Re: panasonic th-50u30a no blink code

well, since we know that the A board isn't sending the 3.3 back to the main board, i will start sourcing a replacement A board, though i may even see if i can dig up another set with a bad sc or broken screen.

thanks for all the help and patience with this one.

[tw2005]

Re: panasonic th-50u30a no blink code

well, since we know that the A board isn't sending the 3.3 back to the main board, i will start sourcing a replacement A board, though i may even see if i can dig up another set with a bad sc or broken screen.

thanks for all the help and patience with this one.

you could always inject 3 volts at pin 7 and see what happens on the P board.

[attainteddragon]

Re: panasonic th-50u30a no blink code

i will do that tomorrow and see how that goes.

[tw2005]

Re: panasonic th-50u30a no blink code

i will do that tomorrow and see how that goes.

I'm always curious plus I'm interested in whether you can see the voltages you want on the caps and the bridge.

Does this model pop up often broken for sale down your way?

Odds are whatever you do find will be SC or Su failure.

I have a panel damaged one but I've kept it as spares and a test unit as it's a single ribbon that's failed so I still have normal picture and a black band

[attainteddragon]

Re: panasonic th-50u30a no blink code

as far as what i get my hands on varies greatly. i have 8 or so pana plasmas that i know of at the moment, but none of the same series.
i think i have around 300 sets at present, so it makes it hard to keep track of them all and storing test chassis's is hard with restricted storage space.

[tw2005]

Re: panasonic th-50u30a no blink code

as far as what i get my hands on varies greatly. i have 8 or so pana plasmas that i know of at the moment, but none of the same series.
i think i have around 300 sets at present, so it makes it hard to keep track of them all and storing test chassis's is hard with restricted storage space.

Just 300, How does one get 300? One thing for sure, it's a lot harder and rarer for me to get one these days yet I see the same people on gumtree flogging repaired Panasonic sets constantly.

Anyway, can't complain. I have 1 x GT30, 1x VT30, 2 xST30, 2 x U30 and a UT30. Plus a mixture of 2009 and 2010 sets

[attainteddragon]

Re: panasonic th-50u30a no blink code

i have many contacts. :P

well, i tried applying 3v to pin 7, but no change of condition, so i did a couple of other things.
removed the bridge, and it is good, but had no thermal paste on it.
lifted the 10ohm resister and it is good.
removed the relays, applied 15v to the activation side. relay click is nice and strong and continuity is present on the points side.

now this is where it gets a little confusing/interesting!

if i bridge the contact side of a relay, i get my 240v to the bridge, and 330v at the main caps. i think that i was wrong with one of my test points earlier and the relays are not being turned on. this is why i never got my 240v at the bridge and no dc on the main filter.
you mentioned something about the 15v supply line to the relays being taken to ground. i'll have a read back and see what i can find.

[tw2005]

Re: panasonic th-50u30a no blink code

i have many contacts. :P

well, i tried applying 3v to pin 7, but no change of condition, so i did a couple of other things.
removed the bridge, and it is good, but had no thermal paste on it.
lifted the 10ohm resister and it is good.
removed the relays, applied 15v to the activation side. relay click is nice and strong and continuity is present on the points side.

now this is where it gets a little confusing/interesting!

if i bridge the contact side of a relay, i get my 240v to the bridge, and 330v at the main caps. i think that i was wrong with one of my test points earlier and the relays are not being turned on. this is why i never got my 240v at the bridge and no dc on the main filter.
you mentioned something about the 15v supply line to the relays being taken to ground. i'll have a read back and see what i can find.

Yeah I mentioned one side has 15v and the other side gets earthed. It 's the earth side that's switched, that's what I saw in that schematic.

surprised nothing happened with 3V at pin 7 maybe another signal is required and missing elsewhere.

[attainteddragon]

Re: panasonic th-50u30a no blink code

i may get lucky and a main could be all that is needed. it just felt weird not having the main caps without a charge.

i'll let you know when i get my hands on one.

i might even crack another pana open in the mean time.