Panasonic TX-32LX85F blink 3 times, P Board-power supply

[zeko]

Hi, in my Panasonic LCD the power supply TNP8EPL90 (TXN/PL10NVA) does not work. The 5.6V Stby is OK. I have P2 connector bridges and have no 25V, 17V and 9V.
After P2 bridge raley works. D854 in secondary has 5.2V.
IC801 5501A (C0DABZZ00012) has no VCC on pin 8 and not out on pin 7, pin 3 is at 2.5V.
IC802 MP2A5077 (C5HAZZZ00012) has on Pin23 320V, pin 10 has unstable voltage.

Please help

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

So, when you turn TV on, does relay click?

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

yes, relay switches .... and go relay off and LED will flash 3 times.
Missing 24V, 17V and 9V. The Stby 5.6V is Ok

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

OK, service manual has PSU schematic:-


Check module voltage on IC802, mounted to heatsink: voltage from pin 23 to pin 4, when relay clicks, should be around 390V... careful, high voltage, you are working on primary side with electrocution hazard.

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

IC802, from pin 23 to pin 4 = 320V
???

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

PFC is not working. Check voltage across C810 capacitor, near IC801 (PFC controller), value 10uF/50V. Also check voltage across C819 capacitor, value 100uF/50V, probably near main transformer.

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

C810 = 0.5v

c819 = 0v

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

OK, so the main switcher is also not working. Check voltage across C82, likely near IC802.

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

C827 goes to pin 10 on the IC802.

C827 value 47uF/50V = voltage unstable 11V-15.5V, measure with MAIN
C827 = voltage unstabile 0V-1.1V, measure with P-GND

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

Yes you're right. C827. The "7" hides on the schematic.

Check D813 and D815 are not shorted. If they aren't, try replacing C827. If that fails, replace IC802.

See page 62 of linked service manual for full schematic of PSU.

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

D813 = OK
D815 = OK
C827 = OK

Is the IC802 broken????
Are there any more test we can do that, to be sure?
If IC802 is broken, there is a cause why?

IC802 MP2A5077 (C5HAZZZ00012)

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

These IC's seem to fail due to internal leakage currents, from heat and transients. How did you determine capacitor C827 to be OK?

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

capacitor C827 I replaced with a new.

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

OK, I'd replace IC802 then because I can see no other fault causing this issue.

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

Can I unsolder the pin 10 of IC802 and check the voltage on C827
whether it is stable now... how high should the voltage?
When do I desolder pin 10 is thus not break anything?

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

That wouldn't help. The IC802 contains internal shunt zener regulator, without it, voltage rises too high and nothing further happens. IC802 regulates voltage, typically would be around 13V to 18V in operation. What is part # for IC802?

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

Ic802 = mp2a5077 (c5hazzz00012)

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

Mp2a5077 (c5hazzz00012)

[tom66]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

Expensive part:-
http://www.ebay.co.uk/itm/MP2A5077-F...item2ec72d4126

Maybe you can get it elsewhere for less.

[zeko]

Re: Panasonic TX-32LX85F blink 3 times, P Board-power supply

there's 2 versions ?