Panasonic TH-55AS670A no picture no sound

[mar1in]

Re: Panasonic TH-55AS670A no picture no sound

i was just wondering, should there be a clicking sound (for a relay ?) when you turn on the TV, because this one seems to be doing no clicking.

Just realised, because I had a look at a similar model of Panasonic the other day and there was a clicking sound once turned on.

That would indicate a problem with the power supply board, but in my case I measured most of the test points with valid voltages.
If I understand it correct, it could be something with the LED driver that is also on that same board?

[Davi.p]

Re: Panasonic TH-55AS670A no picture no sound

Hi, the standby software and diagnostics can be tricked by a not working power rail, check ic5300 pin 2,3,7 on A board

[mar1in]

Re: Panasonic TH-55AS670A no picture no sound

Hi, the standby software and diagnostics can be tricked by a not working power rail, check ic5300 pin 2,3,7 on A board

ok that's interesting, how would I do this, using a jumper wire ?

[mar1in]

Re: Panasonic TH-55AS670A no picture no sound

Hi, the standby software and diagnostics can be tricked by a not working power rail, check ic5300 pin 2,3,7 on A board

i've just measured the pins of IC5300, see image attached.

doesn't matter if TV is in standby or turned on, there is only 16V on one pin, the others are all 0V.
does that indicate a fauly IC ?

the other IC8705 has Voltages (from 0.8V to 120V) on almost every pin except one.

[Davi.p]

Re: Panasonic TH-55AS670A no picture no sound

unfortunately it lacks of enable signal so it is not faulty that chip but probably there are problems in software, the other ic cannot have 120v, are you kidding? Check the meter battery.

[mar1in]

Re: Panasonic TH-55AS670A no picture no sound

unfortunately it lacks of enable signal so it is not faulty that chip but probably there are problems in software, the other ic cannot have 120v, are you kidding? Check the meter battery.

ok, there is no easy fix for a hobbyiest like me i guess.
i have to measure again but i think the multimeter showed something above 100V on two pins, 16V and 5V and 1V and 0.8V on the others

[mar1in]

Re: Panasonic TH-55AS670A no picture no sound

at this stage the best i can do IMO is to look for a spare mainboard

[Davi.p]

Re: Panasonic TH-55AS670A no picture no sound

for the research i made seems 13 blinks are a communication problem (emergency sos) between ic5000 and ic8000 (cpu), since my schematic is for a similar model but the writings are blurred, wait buying a new board, maybe i find something..
it seems ic5000 provides reset signal to cpu

[Davi.p]

Re: Panasonic TH-55AS670A no picture no sound

i found the correct serv. manual and sharp images schematic, so try to check IC5000 pins 1,2,6,8,14,31,32, it is defective or it detects a problem on the sub tensions and shuts all things, comprised the CPU via reset signal.. check well also usb and hdmi connectors with lens, a bent pin can cause all this..