Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

[Chungalin]

EEFL LCD TV. When plugged, relay clicks and after two seconds clicks again, showing a red standby LED blinking seven times. According to attached service manual (which is the most close I've found, as it's same chassis GLP24), 7 blinks mean SUB3.3V missing.

Too bad: SUB3.3V are there during those 2 seconds that the PSU is ON. I've even traced to IC1100 pin 35 (G-SUB3.3V_SENSE) and there're about 3V (3.3V goes through R1410 (10kΩ) before reaching IC1100). Pin 35 is not shorted.

Actually, there're all voltages from PSU while brief time it's on: DVT12V, 17V, TUNER6V and (of course) 5VS (standby). I've also tested other lower voltages from DC-DC ICs (1.8V, 1.2V...). It seems that it cannot detect SUB3.3V although it's there.

Any idea before considering a MAIN replacement?

[Doc38343]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

You could look for a short on the A-board. With it out of the circuit/TV see if the 3.3v pin is shorted, I use my meter in beep mode for diode check red lead on ground (screw hole) and use the black to test both sides of each cap on the rail. Follow that rail to each of those SMD caps and test both ends of it if it beeps on both sides there is a short, if no beep then look at the readings, they should differ. If they are the same that also can indicate a problem. NOTE the short may not be the first one you come to follow the rail all the way to the ICs. Use the schematic to follow the 3.3v rail to all points that interconnect. If you don't do component level repairs then if you do have a short you can buy an A-board with some level of confidence.

You could also disconnect the a board from the power supply and see how the voltages read then. If it is shorted it could pull it down, but yours may be a case where the short only shows up when power on sequence is activated.

[Chungalin]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

There’re no shorts. If there was any, I’d have detected it already, and 3.3V wouldn’t be there, as I stated in opening post.

I’ve even forced PSU to turn on, and all voltages are there, but even then it insists in 7 blink state.

[thoma]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

https://www.electronica-pt.com/esque...s-glp24-29409/

the correct manual

[thoma]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error



WAIT UNTIL GET MANUAL APPEARS!!!

May be help!

[Chungalin]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

Thanks Thoma. That’s the correct manual, but there’re no noticeable changes in the MAIN part. GLP24 chassis means same Main board (A).

The other document is interesting, but there’s no further info about my case. 7 blink is missing SUB3.3V, and they’re present before the TV shuts down itself.

[thoma]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error



https://elektrotanya.com/panasonic_t.../download.html

wait until get manual appears!

[dick_barton]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

The Sub3.3V is rated at 1900mA according to page 54. Can you check the current on the line to see if it's loading the Sub3.3V supply.

I don't know if this is of any help but I see that the set also has a temp sensor (IC2750) on the 3.3V line which I believe other sets have had trouble with due to the ceramic caps connected to them going faulty.

[tom66]

Re: Panasonic TX-L37S10E repair, chassis GLP24, 7 blinks error

Worth poking SUB3.3V with a scope, if you have one available, and see if it's steady 3.3V or oscillating.

Panasonic have been known to combine fault codes in some instances, I've experienced an SOS10 fault that was completely unrelated to a power supply problem.