Polaroid tlx 04244b sound but no picture

[eagle00799]

Hello everyone, I have a tlx 04244b that when turned on the polaroid logo will appear then the backlights shut off, i can see a picture if i shine a light at the screen and the volume works.
I have taken the back off and cant see any bulged caps, I have 5 volts standby and when i turn it on i get the 24 volts to the inverters but i notice the 12 volts will read 12.84 at first but then will drop to 11.89 when the backlights go off. Any suggestions?

[Mr Bill]

Re: Polaroid tlx 04244b sound but no picture

Sounds like one of the inverter boards is the culprit. Can we get pictures of them? I believe the 12v being low when the bulbs turn off is normal because it doesn't have a load on it. I'm sure i'll be corrected shortly

[budm]

Re: Polaroid tlx 04244b sound but no picture

Lets see the pictures of all the board and how they are connected together.The 12V readings are OK, the 12 and the 24 is not tightly regulated.

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

Here are some pics of the boards inplace.

[budm]

Re: Polaroid tlx 04244b sound but no picture

Can you take the resistance reading on the inverter board lamp connector where the Pink & White wires are of both boards?
Since the lamps did flash on that means the BL_ON signal is OK, then it can be bad transformers, caps, MOSFET's on the inverter board.

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

Sorry Budm i dont know how to do this the right way. do you want me to disconnect the pink and white wire connector at the inverter and then touch the 2 probes to the connection points on the inverter? if so my reading is 00.0 on both sides. i have my dmm set on the horseshoe shape(resistance). just not sure where to touch the probes.

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

I also unplugged the pink and white connector from the inverter board and and touched the 2 probes to the pink and white wires and get 00.0 and i get the same reading when i touch the probes together..

[budm]

Re: Polaroid tlx 04244b sound but no picture

You can leave the coonector in place, you can see two exposed terminals on the connector, that is where you hook your Ohm meter to.
Does the meter display has the K or M displaying on the read out. I expect to see 2500
~3000 Ohms reading, not 0 Ohm. Do you also get the same reading on the other conenctor as well?

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

Here is a photo of what i'm doing,there is no k or m and just the horseshoe symbol and this is with the tv unplugged. the exposed locations on the connector are on the bottum side so i went to the exposed locations marked 1 and 2 on the inverter board right behind the connector.

[tom66]

Re: Polaroid tlx 04244b sound but no picture

When the probes are not touching anything, what do you see on the meter?

[budm]

Re: Polaroid tlx 04244b sound but no picture

OK, I see what is going on here, since the TV is using two inverter boards to drive the lamps assembly, they tie the white and pink on one side of the lamp to the master, and then at the slave inverter, they also tie the white and pink at the output of the transformer to form push-pull drive setup.
So I need to get the number of transformer as printed on the body and look up the pin out of the transformers.
Can I see the bottom side of the inveter board also?
Check the fuses (the black and the white one) and the MOSFET's.

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

when probes are not touching this picture shows what i get. When i touch them together i get the same result as the previous picture.

[budm]

Re: Polaroid tlx 04244b sound but no picture

You are having problem just like this one:
https://www.badcaps.net/forum/showth...860#post266860

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture
[LIST]
1-2=6.5m and climbing
1-3=10.05k
2-3=6.7m and climbing
the fuse reads 00.0
the transformer numbers are
T51. 0165. 211 E4 0824 70 B S

[budm]

Re: Polaroid tlx 04244b sound but no picture

All of the MOSFET's? Not just the one I marked. I will look up the transformer pin out.

[budm]

Re: Polaroid tlx 04244b sound but no picture

Here is another thread with the TV that has the same transformer as your:
https://www.badcaps.net/forum/showthread.php?t=18596
See if you get the same readings.
You may have bad lamps if all the readings are OK.

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

yes all the mosfets read very simular, i will check the transformer now.

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

when i check for resistance on the red on red i get O.L m(like the probes are touching nothing). When i touch blue on blue i get 00.0

[eagle00799]

Re: Polaroid tlx 04244b sound but no picture

and i get the same result on the slave inverter also.

[budm]

Re: Polaroid tlx 04244b sound but no picture

OK try to follow this one since it is the same model as your TV:
https://www.badcaps.net/forum/showth...t=17639&page=2
https://www.badcaps.net/forum/showth...t=18596&page=2
Both of them have bad lamps.
I will have to read through all the links and all the posts later.
So far two out of two have bad lamps.