19 polaroid tla-01911c

[Dennis44]

Re: 19 polaroid tla-01911c

Here:

http://www.alldatasheet.com/datashee.../AP4511GD.html


They are one P and one N channel FET in one IC.

DMM to diode check measure from a S1 to G1 reverse probes measure from D1 to G1 reverse probes. Do the same for S2 (2nd FET designation) in the same IC. Look for any shorts on both ICs.

If they check out fine you're going to need to try some test CCFLs on the inverter.

Thanks for the data sheet info. That helped to check out the inverters. They all looked good with my DVM on diode. all juctions were > 600 ohms.

This tv has two driver packs that drive two pair of ccfls in series. They are connected from one side of the secondary in series to the other side of the secondary. the point where the pair are connected in the middle is sent back to the board through some 2k resistors (4k total). I assume this is a current measuring provision.
It is difficult to measure voltages since all this is under the board. I may try to solder some wires and run them out so I can measure them easier with the power on.
Do you know what would be an appropriate dummy load for the ccfls?

Thanks again for you help.
Dennis

[Dennis44]

Re: 19 polaroid tla-01911c

PlaneBill
You are right from what I can tell. The ccfls are in series and the junction seems to be monitored. It almost seems like it keeps track of the differences before it shuts down. A am assuming this since I can swap leads or loads around and it will work for awhile before it shuts down again. Sometimes it will work for a few days.
As I mentioned to Krankshaft I will try to measure the feedback voltages with the ccfls and then resistive loads and look for differences. I am using 820k ohms. Any suggestions?


Thanks,
Dennis

[PlainBill]

Re: 19 polaroid tla-01911c

PlaneBill
You are right from what I can tell. The ccfls are in series and the junction seems to be monitored. It almost seems like it keeps track of the differences before it shuts down. A am assuming this since I can swap leads or loads around and it will work for awhile before it shuts down again. Sometimes it will work for a few days.
As I mentioned to Krankshaft I will try to measure the feedback voltages with the ccfls and then resistive loads and look for differences. I am using 820k ohms. Any suggestions?


Thanks,
Dennis

Yes, I have several. The question is 'Are the CCFLs shutting down because of either a fault with the CCFLs or the inverter; or are they shutting down because of a command from the TV controller?'

I have attached a marked up version of the power supply / inverter board. I would like to see the label next to connector I circled. Could you either take a clear picture, or transcribe it.

One thing to try would be driving the CCFLs using a different inverter - such as the one supplied with a case mod light kit. This might give us a clue if the problem is the CCFLs.

The intermittent nature suggests a bad solder joint. Something else to try is to resolder any suspicious joints on the inverter board, in particular the transformer pins.

PlainBill

[Dennis44]

Re: 19 polaroid tla-01911c

[QUOTE=PlainBill]Yes, I have several. The question is 'Are the CCFLs shutting down because of either a fault with the CCFLs or the inverter; or are they shutting down because of a command from the TV controller?'

I have attached a marked up version of the power supply / inverter board. I would like to see the label next to connector I circled. Could you either take a clear picture, or transcribe it.

One thing to try would be driving the CCFLs using a different inverter - such as the one supplied with a case mod light kit. This might give us a clue if the problem is the CCFLs.

The intermittent nature suggests a bad solder joint. Something else to try is to resolder any suspicious joints on the inverter board, in particular the transformer pins.

PlainBill,
Thanks,
I will try to resolder the board connections on the transformer etc.
What is a case mod light kit?

I had some notes as to the logic levels for P/on B/on and BRI when in standby, On and on and the ccfls shut down. I can't find the notes but I seem to recall there was no difference in the operating and shut down states.

[/IMG]

[PlainBill]

Re: 19 polaroid tla-01911c

[QUOTE=Dennis44]

Yes, I have several. The question is 'Are the CCFLs shutting down because of either a fault with the CCFLs or the inverter; or are they shutting down because of a command from the TV controller?'

I have attached a marked up version of the power supply / inverter board. I would like to see the label next to connector I circled. Could you either take a clear picture, or transcribe it.

One thing to try would be driving the CCFLs using a different inverter - such as the one supplied with a case mod light kit. This might give us a clue if the problem is the CCFLs.

The intermittent nature suggests a bad solder joint. Something else to try is to resolder any suspicious joints on the inverter board, in particular the transformer pins.

PlainBill,
Thanks,
I will try to resolder the board connections on the transformer etc.
What is a case mod light kit?

I had some notes as to the logic levels for P/on B/on and BRI when in standby, On and on and the ccfls shut down. I can't find the notes but I seem to recall there was no difference in the operating and shut down states.

[/IMG]

Excellent picture. I'd suggest verifying the voltages at the P on, B On, and Bri pins. If as you remember there is no difference, this is definitely an inverter / CCFL issue.

A Case Mod light kit is an affectation of those who wished to demonstrate they had too much time and money and too little brains. They would add a window and lights to their computer so they could actually SeE tHe InSiDe!!!

They cost under $10.00 and include 2 12" CCFLs and an inverter. Search 'light mod kit' on eBay for examples. Use the kit inverter to power the TV's backlights; use the kit CCFLs as loads for the TV's inverter.

PlainBill

[Dennis44]

Re: 19 polaroid tla-01911c

[QUOTE=PlainBill]

Excellent picture. I'd suggest verifying the voltages at the P on, B On, and Bri pins. If as you remember there is no difference, this is definitely an inverter / CCFL issue.

A Case Mod light kit is an affectation of those who wished to demonstrate they had too much time and money and too little brains. They would add a window and lights to their computer so they could actually SeE tHe InSiDe!!!

They cost under $10.00 and include 2 12" CCFLs and an inverter. Search 'light mod kit' on eBay for examples. Use the kit inverter to power the TV's backlights; use the kit CCFLs as loads for the TV's inverter.

PlainBill

Ok I verified that the P on, B on and Bri logic levels are the same when the tv is ON as when the tv is On but the lamps are shut down.

I wired the series resistors up so I could measure the feedback voltages with the power on.

If I have the bottom ccfls on the bottom winding and use 450K resistive loads on the top windings I read about 5 volts ac each feedback on the bottom windings and about .160 vac each on the top. If I swap and but the bottom ccfls on the top winding and the resistors on the bottom the voltages change with it.
If I put either ccfl from the top with one of the bottom ccfls and keep the unconnected ccfls with the resistor loads on the other winding it gives a very unbalanced reading of the ccfl feedback. One of the top lamps usually causes it to shut down.

So it appears to be both top lamps or bad connections / arching at the top.

I will leave it wired with only the bottom ccfls running for several days to see if it will stay on. Meanwhile I will get a mod light to further troubleshoot.

How difficult is it to change out the ccfls?

Thanks again
Dennis

[PlainBill]

Re: 19 polaroid tla-01911c

[QUOTE=Dennis44]

Ok I verified that the P on, B on and Bri logic levels are the same when the tv is ON as when the tv is On but the lamps are shut down.

I wired the series resistors up so I could measure the feedback voltages with the power on.

If I have the bottom ccfls on the bottom winding and use 450K resistive loads on the top windings I read about 5 volts ac each feedback on the bottom windings and about .160 vac each on the top. If I swap and but the bottom ccfls on the top winding and the resistors on the bottom the voltages change with it.
If I put either ccfl from the top with one of the bottom ccfls and keep the unconnected ccfls with the resistor loads on the other winding it gives a very unbalanced reading of the ccfl feedback. One of the top lamps usually causes it to shut down.

So it appears to be both top lamps or bad connections / arching at the top.

I will leave it wired with only the bottom ccfls running for several days to see if it will stay on. Meanwhile I will get a mod light to further troubleshoot.

How difficult is it to change out the ccfls?

Thanks again
Dennis

It looks like you're making progress. Either a bad CCFL or an arc is the likely cause; possibly something at the point where the CCFL leads enter the panel.

Changing CCFLs requires some mechanical ability. Different manufacturers use different assembly techniques, and of course they change with time. About all I can suggest is to disassemble it carefully, making sure you keep track of what was where.

PlainBill

[Dennis44]

Re: 19 polaroid tla-01911c

[QUOTE=PlainBill]

It looks like you're making progress. Either a bad CCFL or an arc is the likely cause; possibly something at the point where the CCFL leads enter the panel.

Changing CCFLs requires some mechanical ability. Different manufacturers use different assembly techniques, and of course they change with time. About all I can suggest is to disassemble it carefully, making sure you keep track of what was where.

PlainBill

I have had this tv operating over a week now with only the two bottom ccfls connected and resistive loads on the top winding. So far I have had no problems.
It is amazing how well the set works with only the bottom lamps functioning.
I primarily am using it as a pc monitor.

I did order and receive the case mod lamps.
Before I take this tv apart again do you think the 12" ccfls will work in this 19" unit?

Thanks again,
Dennis

[PlainBill]

Re: 19 polaroid tla-01911c

[QUOTE=Dennis44]

I have had this tv operating over a week now with only the two bottom ccfls connected and resistive loads on the top winding. So far I have had no problems.
It is amazing how well the set works with only the bottom lamps functioning.
I primarily am using it as a pc monitor.

I did order and receive the case mod lamps.
Before I take this tv apart again do you think the 12" ccfls will work in this 19" unit?

Thanks again,
Dennis

They will definitely work as dummy loads for a few minutes. I would be more inclined to use the kit inverter to see if you could determine which CCFL is actually bad.

PlainBill

[Dennis44]

Re: 19 polaroid tla-01911c

[QUOTE=PlainBill]

They will definitely work as dummy loads for a few minutes. I would be more inclined to use the kit inverter to see if you could determine which CCFL is actually bad.

PlainBill

Plain Bill,
I opened up the tv again today. It has been working for several weeks with the bottom ccfls connected and the upper driver having resistive loads.

I used the mod light driver on the suspected upper tv ccfls. It fired them or at least one ccfl. I did not open up the screen to see each ccfl. I noticed the mod light driver has both of its lamps in parallel so if one of the tv's ccfls were shorting it would have effected both. However a weak one would let the other one work. ( I powered the mod light driver using a 12volt power supply that was separate from the tv.)

Next I used the upper tv drivers on the mod light ccfls. Both lit up and were relatively balanced in terms of feedback voltages. I left it on over an hour.

After I reconnected the tv's upper ccfls to the tv's upper drivers it would shut down after initializing.
Measuring the ac feedback voltages during the time the lights were on revealed that the blue/black wires read >7 vac while the pink/white wires read <1 volt. This seems to indicate that the pink/ white circuit is not drawing much current.

I wanted to have some ccfls available before I attempt to dismantle the screen. Do you have the information I need to get the best match?

Thank you,
Dennis

[PlainBill]

Re: 19 polaroid tla-01911c

[QUOTE=Dennis44]

Plain Bill,
I opened up the tv again today. It has been working for several weeks with the bottom ccfls connected and the upper driver having resistive loads.

I used the mod light driver on the suspected upper tv ccfls. It fired them or at least one ccfl. I did not open up the screen to see each ccfl. I noticed the mod light driver has both of its lamps in parallel so if one of the tv's ccfls were shorting it would have effected both. However a weak one would let the other one work. ( I powered the mod light driver using a 12volt power supply that was separate from the tv.)

Next I used the upper tv drivers on the mod light ccfls. Both lit up and were relatively balanced in terms of feedback voltages. I left it on over an hour.

After I reconnected the tv's upper ccfls to the tv's upper drivers it would shut down after initializing.
Measuring the ac feedback voltages during the time the lights were on revealed that the blue/black wires read >7 vac while the pink/white wires read <1 volt. This seems to indicate that the pink/ white circuit is not drawing much current.

I wanted to have some ccfls available before I attempt to dismantle the screen. Do you have the information I need to get the best match?

Thank you,
Dennis

Good work, Dennis. Sorry, I don't have much hope of your getting replacement CCFLs without opening the lcd panel. It's been pretty well documented that two panels from the same factory can have the same part number, but different diameter CCFLs.

PlainBill

[Dennis44]

Re: 19 polaroid tla-01911c

[QUOTE=PlainBill]

Good work, Dennis. Sorry, I don't have much hope of your getting replacement CCFLs without opening the lcd panel. It's been pretty well documented that two panels from the same factory can have the same part number, but different diameter CCFLs.

PlainBill

Bill,
Thank you for your help. I have not had the time to spend on this tv lately.
Also, since it is working with only two lamps my incentive is not great.
I will eventually find out what lamps are in the set and let you know.
Dennis

[Dennis44]

Re: 19 polaroid tla-01911c

Bill,
The tv has been working all this time. However it did start shutting down again.
I noticed the resistive loads I installed for the top ccfls had burned badly so they were causing an unbalance.

I went ahead and dismantled the lcd panel. I found a wire to the top set of ccfls had overheated and was completely open.

I cut the burned area away from the wire insulation and re-soldered it to the ccfl.
Now everything is back to normal. All feedback voltages are about 4.5 vac.

I did measure the ccfl and it appeared to be about 2mm by about 420 mm total length.
I found a supplier that claimed this model used a 2.6mm by 413 mm.

I was curious if you had any information about these ccfls in the event I do need to replace them.

Thanks again for your help.
Dennis

[PlainBill]

Re: 19 polaroid tla-01911c

Bill,
The tv has been working all this time. However it did start shutting down again.
I noticed the resistive loads I installed for the top ccfls had burned badly so they were causing an unbalance.

I went ahead and dismantled the lcd panel. I found a wire to the top set of ccfls had overheated and was completely open.

I cut the burned area away from the wire insulation and re-soldered it to the ccfl.
Now everything is back to normal. All feedback voltages are about 4.5 vac.

I did measure the ccfl and it appeared to be about 2mm by about 420 mm total length.
I found a supplier that claimed this model used a 2.6mm by 413 mm.

I was curious if you had any information about these ccfls in the event I do need to replace them.

Thanks again for your help.
Dennis

There are a number of suppliers that can be found by a Google search 'CCRL backlight' or similar terms. From what I have been able to discover, LCD panel manufacturers may use different diameter (and possibly length) CCFLs in different production runs of a panel.

PlainBill

[Dennis44]

Re: 19 polaroid tla-01911c

There are a number of suppliers that can be found by a Google search 'CCRL backlight' or similar terms. From what I have been able to discover, LCD panel manufacturers may use different diameter (and possibly length) CCFLs in different production runs of a panel.

PlainBill

Thanks Bill,
If I can only find a 2.6 mm and the originals are 2.0 mm I wonder if it would cause problems to mismatch them?

If at some time a ccfl does go out I will measure the diameters more precisely and replace them all.

Dennis

[theoverseer]

Re: 19 polaroid tla-01911c

can someone help me my polaroid tla-01911c screen just goes white i dont know why all i did was turn it off then on and it started up on a white screen. does anyone know why that would happen? message me asap please

[PCBONEZ]

Re: 19 polaroid tla-01911c

All white means the back-light is working but the video isn't getting to the LCD panel.
Good chance it's just a loose connector cable between the video board and the LCD panel.

[Dennis44]

Re: 19 polaroid tla-01911c

can someone help me my polaroid tla-01911c screen just goes white i dont know why all i did was turn it off then on and it started up on a white screen. does anyone know why that would happen? message me asap please

I did not see this symptom on my set. It does sound like the video signal is absent. Is the sound still working?
Dennis

[PlainBill]

Re: 19 polaroid tla-01911c

All white means the back-light is working but the video isn't getting to the LCD panel.
Good chance it's just a loose connector cable between the video board and the LCD panel.

Or a blown fuse, or other defect on the Tcon board.

PlainBill

[theoverseer]

Re: 19 polaroid tla-01911c

idk if theres sound i had it hooked up to my laptop so its in hdmi i tried putting it in cable to see if theres sound but nothing happened. now when i turn it on it blinks black like 4 times then the screen slowly goes white. pcbones where would those wires be so i can check it out i have to tv opened already