Jvc lt-50e73

[fester]

Hi friends.
I have this TV for repair,everything worked,only sound not. Audio amplifier cirquit is workind,if i touched on input pins,i hear noise comming form speakers. I found somewhere that this TV have problems with corrupted firmware so tried to flash firmware found on net with the same LCD number. From this time,TV is not working anymore, at start,it only blinks with JVC logo,only fraction of second,blue led stay on and nothing..the same behavior is now also with original dump. I thried to erase flash chip first(fill with #FF),then flashing,no change.. Flash chip is ok,i can write,read,verify content with programmer, all cables are connected,i see no signs of cold solder connection under microscope,nothing is looking bad. So,question is,can this be some problem with firmware or i broke something else maybe?

TV model: JVC LT-50E73
Board number: msdv3223-zc01-01
flash chip (U6) : 25Q64BSIG
panel : V500-HK1-PS6

[R_J]

Re: Jvc lt-50e73

If you shine a light at the lcd screen, can you see any image? It sounds like you have a failed backlight

[Andrew F. Ali]

Re: Jvc lt-50e73

fester are you trying to say everything except sound is working. In other words there is picture, menu command probably working, able to switch inputs but no sound from the speakers and the test you did proved the Audio amp to be working? Is this correct??

[fester]

Re: Jvc lt-50e73

fester are you trying to say everything except sound is working. In other words there is picture, menu command probably working, able to switch inputs but no sound from the speakers and the test you did proved the Audio amp to be working? Is this correct??

No,i lost picture when i reflashed fw. Dont know if audio is now working because i see nothing on the screen,cant test it but amplifier electrically is ok . TV also react to IR remote - LED is blinking. I will try it with flashlight tomorow,will see if is panel completely without picture or only backlight missing.

[R_J]

Re: Jvc lt-50e73

Are you sure you used the correct firmware? Were you flashing the firmware to correct the no audio problem?

[fester]

Re: Jvc lt-50e73

Yes i tried to repair this audio problem with firmware flashing. i used fw found here :

https://www.elektroda.pl/rtvforum/topic3376218.html

, this dump looks like correct version for my tv.

[fester]

Re: Jvc lt-50e73

ok,friends,i looked at the screen with flashlight..picture is there,backlight is missing..

[Andrew F. Ali]

Re: Jvc lt-50e73

We will need to see photos of the boards to advise better.

[fester]

Re: Jvc lt-50e73

here it is,t-con board is under metal plate,i dont removed it yet.

[fester]

Re: Jvc lt-50e73

here it is,t-con board is under metal plate,i dont removed it yet.

hups,t-con is visible,under metal plate is only display board

[R_J]

Re: Jvc lt-50e73

There look to be two plugs with two wires each that feed the backlight (Con5, Con2), measure the voltage on each wire while turning on the tv. Do this for both backlight connectors.
On one pin you will likley get 100-140 volts (guess) on the other you should get 10 - 20 volts (guess) if you get the 100-140 but 0 volts on the other pin it is likely an open led string

[fester]

Re: Jvc lt-50e73

i have voltage spikes on both connectors,max value what i see on multimeter is arround 90V. if i disconect one connector,no matter which one,the same behavior,only short blink of backlight.

[budm]

Re: Jvc lt-50e73

i have voltage spikes on both connectors,max value what i see on multimeter is arround 90V. if i disconect one connector,no matter which one,the same behavior,only short blink of backlight.

Voltage spike on ALL 4 of the LED connector pins?

[fester]

Re: Jvc lt-50e73

no,i meassured voltage between two pins of one connector

[budm]

Re: Jvc lt-50e73

You need to use chassis GND and the ref. GND for the meter.
Please repeat the test on all 4 pins by leaving the probes in place while keeping an eye on the meter during TV powered on to see how high the Voltages go up to for each pin.

[fester]

Re: Jvc lt-50e73

Sorry for delay,i am too busy last few weeks..here the meassurements in volts..

[mtoivanen]

Re: Jvc lt-50e73

Did you got the sound problem solved? I recently got same JVC unit, everything works, except sound. Got sound working few times when I did factory reset, but was gone after shutdown.

[nomoresonys]

Re: Jvc lt-50e73

maybe simple reset, unplug tv wait about a minute hold power button in on tv for about 30 seconds then try it, did you try a firmware update?

[fester]

Re: Jvc lt-50e73

Did you got the sound problem solved? I recently got same JVC unit, everything works, except sound. Got sound working few times when I did factory reset, but was gone after shutdown.

Yes,solved with reflashing firmware.

[mtoivanen]

Re: Jvc lt-50e73

Yes,solved with reflashing firmware.

Okay. The firmware needs some kind of external flasher I guess? Atleast the USB update with the file mentioned on this topic did not work via USB.