Sound and picture but no backlight

[budm]

Re: Sound and picture but no backlight

Main Transformer T1 is fine and it is working otherwise you will not have the 5VSB (fed from always on 5V), Switched 5V (fed from always on 5V) and Switched 12V (fed from always on 12vV), and the 60V (fed from always on 60V) feeding the boost converter.

[JCdes]

Re: Sound and picture but no backlight

Pulled d200 and it's ok.

[budm]

Re: Sound and picture but no backlight

Pulled d200 and it's ok.

No resistance reading on both directions, correct?
And if you check the resistance of the two solder pads of D200 without D200 in place, what resistance do you get in both directions?

[JCdes]

Re: Sound and picture but no backlight

you keep swimming at wrong direction... as you dont have the equipment to measure led in circuit currents.... put your DM 200.V DC red probe on any LED+ and test black probe on all LED- one by one when you turn on the set post your results each led -V No. --- this is -V currents boost circuit ( always i corrected this thought over this forum .. LED circuit / UNIT depending on current not Volts. ) so all yours parts replacement was just spending parts and time.

Will do that tomorrow... I don't think replacing parts and spending 10 bucks in them is a waste as I consider it a learning experience plus new parts last longer after all. I'll let you know how the test came out.

I would be lying if I told you that I think I did that and I only see a change in the multimeter reading if the corresponding led+ And led- pair for a specific strip are touched eg: First+ with first - which is the bottom strip pair, second + with second - which is the second to last and so on. So I will do the test cause I don't remember if I've done that already.

Thanks for trying to help.

[JCdes]

Re: Sound and picture but no backlight

No resistance reading on both directions, correct?
And if you check the resistance of the two solder pads of D200 without D200 in place, what resistance do you get in both directions?

With red probe on middle pin of d200 I get resistance but with the probes on both ends (1 and 3) nothing. I'll do the test on the solder pads tomorrow after work.

[Diah]

Re: Sound and picture but no backlight

Will do that tomorrow... I don't think replacing parts and spending 10 bucks in them is a waste
I would be lying if I told you that I think I did that and I only see a change in the multimeter reading

Thanks for trying to help.

i am sure you will find the issue soon.
my points not about spending $ .. the problem we are facing knowing days.. spare parts become very bad manufactured. for me ONE Original parts of set tested working will never replace it even just for test only...
good luck wish you.

[budm]

Re: Sound and picture but no backlight

With red probe on middle pin of d200 I get resistance but with the probes on both ends (1 and 3) nothing. I'll do the test on the solder pads tomorrow after work.

D200 is the Dual diode with Common Cathode (center pin), the two outer legs are anode and they are tied together to put the two diodes in parallel that is why you can see the trace connecting the two outer pins together.

[JCdes]

Re: Sound and picture but no backlight

Ok, I will not be able to do tests today. Family matters that I must attend... So I'll ask you guys so that if I get home early I'll know what I'm looking for.

Diah: When I test the led+ With all the led-'s... What should I see? Should it give me a reading with all the -'s or only with the - that belongs to thats specific strip?

Budm: Should I see a specific resistance or none at all?

Once again thanks for the time you're spending with my problem and will to learn something new.

[budm]

Re: Sound and picture but no backlight

I expect the resistance reading to be in K Ohms range on the solder pads of D200..

[Diah]

Re: Sound and picture but no backlight

Diah: When I test the led+ With all the led-'s... What should I see? Should it give me a reading with all the -'s or only with the - that belongs to thats specific strip?

yours POST #21

each strips contain same amount & Type of LED units, testing direct on + & - LED socket will show us if there are differences at pulling currents between the strips. in other words ( we are testing the build in ziner diode at LED unit ) which by time the value changed (decrease). this change LED tester would pass it as success test. but the power boards LED circuit will not pass it ( failed ) because its designed on certain currents depending on Panel size and the amount / type of LED units.

reading the high/ low value after powering up will tell us if our suspect correct or not.

[JCdes]

Re: Sound and picture but no backlight

Sorry for the long delay guys... I suffered a total rupture of my achilles tendon and have been recovering slowly... As soon as I can stand I'll do the tests...

[JCdes]

Re: Sound and picture but no backlight

My wife gave me this gift... Do you guys think it could work?

[JCdes]

Re: Sound and picture but no backlight

Recovery from this surgery is torture...

[JCdes]

Re: Sound and picture but no backlight

I can almost walk ok... I'll try to get back on this tv tomorrow. Gonna check the power levels you requested. Btw how about that board my wife gave me hoping it could work? Is it crap?