General CCFL inverter question

[angelos]

Good evening.
If a ccfl lamp lights up for 2 seconds and only the one side of the lamp lights up and then it shuts down. Sometimes it works fine.
Is it a lack of high voltage? Lamps tested with HV tester and they are all ok.
There is a plug from tcon to inverter with sync info. If this info is missing can there be this same issue?
I checked the ballast transformers and didnt notice any large resistance difference.

[Andrew F. Ali]

Re: General CCFL inverter question

That symptom has nothing to do with sync info but could either be not enough high voltage or bad CCFL.

[budm]

Re: General CCFL inverter question

Those CCFL tester does not have any protection circuit to detect if the lamp is drawing too much current or not, so worn out lamp will draw more current but it will still light up with tester.

[Andrew F. Ali]

Re: General CCFL inverter question

those ccfl tester does not have any protection circuit to detect if the lamp is drawing too much current or not, so worn out lamp will draw more current but it will still light up with tester.

+10

[angelos]

Re: General CCFL inverter question

Is there anything i can do to prove its a lamp or lack of high voltage? I dont have those kinds of lamps and getting them takes 3 months....

[mmartell]

Re: General CCFL inverter question

If you're talking about one suspect lamp swap it with a lamp in another location and see if the problem moves.

[Andrew F. Ali]

Re: General CCFL inverter question

The Inverter is working since you are getting Hi-voltage out from the transformers which are working. Do as mmartell suggests and then have patience and wait for the new lamps.

[angelos]

Re: General CCFL inverter question

If you're talking about one suspect lamp swap it with a lamp in another location and see if the problem moves.

If all the lamps do not illuminate fully how do i determine which ones to swap out with which? All the lamps illuminate 1/3 of the way before shutting off. I have some lamps which i must just check the length? Does diameter make a difference???

[Andrew F. Ali]

Re: General CCFL inverter question

How many lamps does this TV carry? To fully test the Inverter you could use those house spiral fluorescent lamps and remove the screwed lamp socket part to remain with the spiral and the 2 thin sires an connect them to the Inverter outputs. You can use the 13-20W size depending on the TV screen size. I have 4 of them to test Inverters, but opt to convert the CCFL backlights to LED backlights if the lamps are the fault and repair/replace Inverters if I can get them if the CCFLS are good.

[angelos]

Re: General CCFL inverter question

Hi Guys, I have feedback on those lamps. I replaced 10 out of the 14 lamps with new and the problem persisted. Then i started swapping out the old lamps on the last 4 with no luck. I did however notice that the top two lamps if they are removed the lamps illuminate properly so i thought the fault lay on that rail. I replaced the HV transformer with another and still no luck. The problem persists. Please check the photos's.

[dick_barton]

Re: General CCFL inverter question

You may have a capacitor fault between the HV transformer and lamp connector.

[R_J]

Re: General CCFL inverter question

Likely a problem with the inverter for those top ccfl's, when the top lamps are driven they load down the whole inverter circuit.

[angelos]

Re: General CCFL inverter question

You may have a capacitor fault between the HV transformer and lamp connector.

There are no capacitors between the HV transformers and the lamps. I will check again just to make sure. I must say though that once the tv's backlights switch off and the tv is running without back lights if you give a it a good knock then suddenly all the lights come on and the set works fine for a while. Weird since i thought that if the backlight inverter trips it locks in that state until you power cycle the tv. This might be a dry joint somewhere. I knocked on all the smd components but that never made it work but suddenly then if you smack it it comes to life. This is really weird.
I discovered this symptom today!!!!!!!!!

[R_J]

Re: General CCFL inverter question

You could try posting some pictures of the inverter board etc, maybe someone will recognize the board. maybe list the inverter board numbers also

[budm]

Re: General CCFL inverter question

you could try posting some pictures of the inverter board etc, maybe someone will recognize the board. Maybe list the inverter board numbers also

+10

[mmartell]

Re: General CCFL inverter question

Oh I have a new guess. That looks like it could be the infamous SSL-14xxx inverter. If someone removed that inverter improperly before it got to you then it's fate was sealed.

Remove each tube and check each connector for signs of carbon/burn/blackness. That metal should be shiny and smooth.

Like the one on the left, not the right...

[angelos]

Re: General CCFL inverter question

Oh I have a new guess. That looks like it could be the infamous SSL-14xxx inverter. If someone removed that inverter improperly before it got to you then it's fate was sealed.

Remove each tube and check each connector for signs of carbon/burn/blackness. That metal should be shiny and smooth.

Like the one on the left, not the right...

I will check and get back to you with photo's. Had been sick... Thanks.

[angelos]

Re: General CCFL inverter question

Hi Guys,
I got the pictures. You will see that the inverter board is number SSI_400_14A01 in the pictures i uploaded. I removed the HV connection to look for a carbon path or carbonised contacts and did not notice any. I did however see that these contacts are not shiny but rather have changed color due to getting hot.
I took oscilloscope readings on the transistors driving the HV transformers primary winding once when the inverter runs correctly and once when it comes up with that half lit tripping story.
What is evident is that the duty cycle when running correct is about 50% but when its about to fail its almost 95% "on".
Is this a clue to whats happening?

Photo's to follow

[angelos]

Re: General CCFL inverter question

These are the pictures

[mmartell]

Re: General CCFL inverter question

Reeceyburger had a long thread on this inverter. He said it's full of dry joints so you may as well check that out. Maybe search for the thread for all the ins and outs.