Panasonic TC-42PX14 Zener Diode

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

What page this Q5522 is on?

budm, it is on page 30, what do you think?

[budm]

Re: Panasonic TC-42PX14 Zener Diode

More explanations: Page 46, Q5522 monitors 4 Voltages to make sure they are present, SUB5V, BT30V, SUB9V, and FV15V through 4 OR GATES (Dual) diodes D5521, D5522.
That is why it is called VOLTAGE DROP ERROR DETECT since the MCU is not sending out the signal to turn on FV15 as I explained earlier.
Something is locking out the the MCU.

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

More explanations: Page 46, Q5522 monitors 4 Voltages to make sure they are present, SUB5V, BT30V, SUB9V, and FV15V through 4 OR GATES (Dual) diodes D5521, D5522.
That is why it is called VOLTAGE DROP ERROR DETECT since the MCU is not sending out the signal to turn on FV15 as I explained earlier.
Something is locking out the the MCU.

Yeah, I saw D5521 and 5522 on top of A board with the Q5522 in between.
I really thought this was the problem as per panasonic Power Led Blinking
Timing Chart, it gives 4 possible reasons that causes the 10 blinks on A board
and Tuner Power SOS is one of them. As you can see, one end of the
Transistor Q5522 goes to the Tuner on the A board. OK back to the
drawing board. Thanks for your input.

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

I just noticed if you follow line 4 from page 30 it goes to page 31
which leads to MPU

[budm]

Re: Panasonic TC-42PX14 Zener Diode

That out put on the Collector is for sending the SIGNAL (SOS) indicating that one or more of the 4 power supplies have gone out, it is not used for powering the circuits, there should be no output from this transistor if all 4 power supplies are working. So the error light is correct since the transistor is turn on due to failed power supply.
If F15V is not present, then there will no sub1.8, sub1.3, sub5v, sub3.3v.So F15V is the key voltage source. as shown on page 46.
On page 49, are you getting STB3.3V feeding the MCU IC1100?

[budm]

Re: Panasonic TC-42PX14 Zener Diode

Line 4 BUSS signal line:
TVSUBON on line 4 is the output from MCU IC110 PIN28 to feed the power supply to turn on IC603, its output is then feed IC502 pin 1 as I have already traced out in the PDF.

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

That out put on the Collector is for sending the SIGNAL (SOS) indicating that one or more of the 4 power supplies have gone out, it is not used for powering the circuits, there should be no output from this transistor if all 4 power supplies are working. So the error light is correct since the transistor is turn on due to failed power supply.
If F15V is not present, then there will no sub1.8, sub1.3, sub5v, sub3.3v.So F15V is the key voltage source. as shown on page 46.
On page 49, are you getting STB3.3V feeding the MCU IC1100?

I will check it out.

[budm]

Re: Panasonic TC-42PX14 Zener Diode

Main key right now is that the MCU IC1100 pin 28 is not sending the signal to turn on F15V, that is the bottom line, there is no output from MCU.

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

Main key right now is that the MCU IC1100 pin 28 is not sending the signal to turn on F15V, that is the bottom line, there is no output from MCU.

Going to get some rest, been reading and listening to your advise.
Will hack at again tomorrow. Thanks budm!

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

That out put on the Collector is for sending the SIGNAL (SOS) indicating that one or more of the 4 power supplies have gone out, it is not used for powering the circuits, there should be no output from this transistor if all 4 power supplies are working. So the error light is correct since the transistor is turn on due to failed power supply.
If F15V is not present, then there will no sub1.8, sub1.3, sub5v, sub3.3v.So F15V is the key voltage source. as shown on page 46.
On page 49, are you getting STB3.3V feeding the MCU IC1100?

No, STB3.3v to MCU 1100. More trouble shooting ahead.

[budm]

Re: Panasonic TC-42PX14 Zener Diode

May be that is why you are not getting the signal output from MCU pin 28 to turn on the F15V.
Need to look through the diagrams to see who generates the STB3.3V.

[budm]

Re: Panasonic TC-42PX14 Zener Diode

OK, I found out where STB3.3V is coming from, (IC5480 PIN8), see PDF.
STB5V (Standby 5V) goes into pin7, an the output of 3.3V comes out on pin8 of IC5480.

[mr.sky]

Re: Panasonic TC-42PX14 Zener Diode

budm, sorry for not getting back to you. Took a vacation down
in southern Mexico, Morelia Michoacan. I got back a few days
ago, and got frustrated with this tv, I just went and bought
another A-board and tv worked fine. Sold tv on Craigslist.
Not sure if I want to buy another fixer upper, especially
Panasonic Plasma. You are one special guy, always here to
help the community on this Forum.