JVC LT-32EX38 2sec to black I think

[ryan74]

When i turn this tv on the led turns green and stays green.
I get 2 sec to black but sometimes i get a few sec. of sound sometimes i dont.
sometimes its a few sec of static sound sometimes it is a few sec of normal audio.
Inv voltage is:
(14)empty
(13)DIM = 1.54vdc
(12)ENA = 3.25vdc
(11)error = 0.0vdc
(6-10) = G
(1-5)VCC = 24v.

I cant find a service manual, pwb schem. hopefully someone can supply me with one.
the PWB is # LCA90713(sfn-9001a)
The 24vdc VCC should be correct but not sure about other readings.

my first thought is main board but i dont know what voltage readings i should be getting.

Is the part in pic a status led? it does not light up if so.

I noticed in on the tuner board the chip got pretty hot to the touch but does not burn me.

[drpj23]

Re: JVC LT-32EX38 2sec to black I think

...That could be a photodiode....that detects light and wipes encryption data for HDMI (not kidding)

What are the other voltages from the power supply?
And what is the panel model?

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

The panel is samsung LTA320WT-LO6
I'll check other voltage and post pics of the connectors tomorrow.

[budm]

Re: JVC LT-32EX38 2sec to black I think

As far as the backlights concerned, they should be on since it is receiving all the correct voltage (24vdc), signals (ENA (BL_ON) 3.25v) and Error (0V = OK), and the Dimming control which are what the inverter board needs to operate.
Can we see more pictures of the inverter board?
Spec sheet.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

Thank you for the specs and explaining ENA budm, I didn't know that was bl_on but I guess it makes sence.
This tv came from the dump and was very dirty outside and a bunch of spiderwebs inside. The screen looks ok besides a scratch I have to try and fix.
It could have been thrown around.
I have been thinking about opening the panel to check lamps and connections. I can't isolate 1 at a time because the inv board snaps into a strip. Its all or nothing. Plus I think I would get an error from inv.
I'll post inv pics later, its too late here now.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

I have to get the inverter pics later. camera battery died.

1)3.24Vdc
2)1.46V
3)4.99V
4)23.85V
5)23.85V
6)25.3mV
7)24.7V
8)2.8mV
9)2.8mV
10)2.8mV

1)5.4mV
2)5.4mV
3)5.4mV
4)13.69V
5)13.69V
6)13.69V
7)13.69V
8)1.54V
9)30mV
10)3.24V
11)29.2mV

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

inverter

[budm]

Re: JVC LT-32EX38 2sec to black I think

What is the P/N of that PWM IC with 20 pins in pictures number 4.? Some of the pictures are really out of focus.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

Sorry about pic quality im still trying to figure out my new camera i think auto focus is not good to use. i did have macro on.
P/N: SEM2006
0717
I think i figured out the backlight issue. one of the lamps is cracked and shorted.
I dont have the proper size replacement so could i use a U shape in place of 2 straight lamps

[budm]

Re: JVC LT-32EX38 2sec to black I think

The straight tube has return circuit at the end of the tube to complete the lamp circuit, When you use U shape tube, there will be no path for the current return path because both feeding terminals are putting out the same voltage. U tube also needs much higher voltage to operate because of the total length of the U tube.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

i went ahead and tried the u tube. I took out 2 lamps and soldered wires to the connections on left side(pic1).
so far its working.

[budm]

Re: JVC LT-32EX38 2sec to black I think

That's good, does the U tube light up all the way? Also check to see if the transformer get hot, you mat be able to get away with it, it sounds like the outputs are not in phase so that's why it is lighting up.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

I didnt power it up when it was open but i dont see any light issues on screen.
When I looked at the rail on the right side I assumed it was a return. I already closed it up but I think I should check transformer for heat. I will run it for 24hrs also.

Inside panel it looks like a hack job but noone should see it. I siliconed rubber mount to panel for support.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

the transformer on top is fairly warm to the touch, middle one is warm. and bottom is warm. none were really hot but it hasnt been on long. I will leave it on a while and recheck. I have a lazer temp gun if you know how hot it should be running.

I checked how hot with temp gun and top transformer was 140deg C. The other 2 were about 132deg C.
the panel itself on back side reaches 105deg C from lamp heat.

[budm]

Re: JVC LT-32EX38 2sec to black I think

What is the room temperature? if it is 25C, that means the temp rise is about 115c, that is hot, the enamel wire rating ia about 135~150C. Keep an eye on them, I wonder if it will get even hotter with the back on.

[ryan74]

Re: JVC LT-32EX38 2sec to black I think

my mistake
those were fahrenheit temps.
the transformers run about 60deg C. and the back side of panel is 40deg C
room temp is 23deg C

I think it will be ok.