Sony klv-37u300a t-con issue

[kumag]

Hello to everyone! Happy new year to all of us.. After a lot of reading to different lcd tv threads
here in badcaps.. i dared to fix my bravia klv37u300a with a smearing colors and image retentions. The tv also has a max bright setting to attain skin tone color. I followed instructions i've learned here in replacing the AS15-F but AS15-G was the only available part nearby.. i've checked first the Vgam readings and here is the result:
vgama
1. 16.12v
2. 16.02
3. 14.05
4. 12.73
5. 11.78
6. 11.20
7. 10.72
8. 10.42
9. 10.17
10. 7.47
11. 7.30
12. 6.76
13. 6.93
14. 15.16
15. 14.60
16. 12.65
17. 11.36
18. 13.30
19. 12.9
20. 11.9
21. 15.84
22. 12.59



so, the replacement of as15-f to a new as15-g was successful.. the image retention was gone but i have to turn down picture control to almost 0 to acheive skin tone.. the colors are correct but very dim.. when picture control is set in increment. ..faces becomes oily looking and neon..
I am appealing to masters here to help me finish my repairing adventure.. this is the new reading after replacing as15-f with as15-g:

1. 15.4v
2. 15.2
3. 13.5
4. 12.3
5. 11.4
6. 10.8
7. 10.4
8. 10.1
9. 9.9
10. 7.4
11. 7.3
12. 6.8
13. 9.9
14. 4.8
15. 4.6
16. 6.1
17. 9.8
18. 5.4
19. 3.4
20. 2.4
21. 0.5
22. 0.3

help me masters

[kumag]

Re: Sony klv-37u300a t-con issue

pics after replacement:

[tibimakai]

Re: Sony klv-37u300a t-con issue

I have a very similar problem that I'm working on and the second IC replacement did not work out for me. Not sure what happened. I have also lifted with the Kepton tape(used around the IC) some capacitors.
I have ordered new IC and I'm waiting now.
Those voltages don't look right. You have some spikes there.
Tom said, that the voltages should be lowering to one end.
Not sure if it's OK to replace F with G. I would use the right part in there.

[T-con]

Re: Sony klv-37u300a t-con issue

I agree with tibimakai, and tom66, voltages should be decreasing, the chip is compatible mine is as15-hf and replaced as15-f worked fine, i suggest you double check your solder, i had problems replacing the chip, thought its well soldered but not.

https://www.badcaps.net/forum/attach...8&d=1388364402

[kumag]

Re: Sony klv-37u300a t-con issue

Thanks for the replies.. i've decided to resolder the as15-g and carefully checked its pins of micro solder bridges, cleaned the t-con board with lacquer and re-assembled it. It is now operational.
thanks again masters..here comes the pics.

[tom66]

Re: Sony klv-37u300a t-con issue

The voltage can either increase or decrease from Gamma 1 to Gamma 16 but it must go in one way only - in other words, it can only increase -OR- decrease. Not both. If it does both, the chip is bad. If you test gamma voltages now, the curve of them should be somewhat S-shaped, around the mid point of 7.5V to 8V, symmetrical on both sides.

[T-con]

Re: Sony klv-37u300a t-con issue

Thanks for the replies.. i've decided to resolder the as15-g and carefully checked its pins of micro solder bridges, cleaned the t-con board with lacquer and re-assembled it. It is now operational.
thanks again masters..here comes the pics.

Good!

[T-con]

Re: Sony klv-37u300a t-con issue

The voltage can either increase or decrease from Gamma 1 to Gamma 16 but it must go in one way only - in other words, it can only increase -OR- decrease. Not both. If it does both, the chip is bad. If you test gamma voltages now, the curve of them should be somewhat S-shaped, around the mid point of 7.5V to 8V, symmetrical on both sides.

Thought all gamma chips have decreasing voltages, thanks!

[budm]

Re: Sony klv-37u300a t-con issue

I use flux cleaner to clean out all the flux, it could have been contamination from the soldering. The circuit has lots of op-amp in it. Good job.

[kumag]

Re: Sony klv-37u300a t-con issue

Good morning guys! I'd like to discuss the scope of this 37u300a.. That lcd tv was accidentally plugged to an unregulated AC supply generated by a 5kva machine.. so the psu board failed. We ordered the board then the tv ran again with audio and controls but but a complete no picture and black screen.. The tv was set aside for a half year, wall attached and tried to warmed it up from time to time, hoping that it could recover that way.. until i surfed the net about lcd tvs and downloaded its repair manual that pointed me to an understanding of a wrong panel_power vcc. The purchased psu board has an output of 5v instead of 12v that the t-con auo t370hw02 required. I managed to traced it on ka278r05 and replaced it with kia78r12pi since thats the only numer available, i followed some circuit modification specified to panel_power vcc.. picture resumed but wrong colors with image traces.. until i found this forum and read the topics posted by: tibimakai,t-con,tom66,budm and some ts here. your topics guides a lot.. long live!

[budm]

Re: Sony klv-37u300a t-con issue

the KA278R05 is the 5V LDO (), and you put in 12V LVDO instead. The input to the 12V LVDO should be around 14V for it to properly regulated.
Where is this ka278r05 located at? Main board? Power supply board?

[kumag]

Re: Sony klv-37u300a t-con issue

the KA278R05 is the 5V LDO (), and you put in 12V LVDO instead. The input to the 12V LVDO should be around 14V for it to properly regulated.
Where is this ka278r05 located at? Main board? Power supply board?

the ka278r05 is located at psu.. pls.see my attachment.

[budm]

Re: Sony klv-37u300a t-con issue

The input Voltage to your new 12V regulator IC is only 8 Volts! that is not going to work, that is why they have 5V regulator in the original place.
As you can see in the diagram, if you are going to use 12V regulator, you must properly setup the jumper J1 and R14.

[kumag]

Re: Sony klv-37u300a t-con issue

yes. i did the j1 and r14 modification.. the kia78r12pi works well up to now..and im planning to replace it with 278r12 when it becomes available in stores here in manila.

[budm]

Re: Sony klv-37u300a t-con issue

OK, so you are getting 12V OK to the T-CON now. Can we see what the picture on the screen look like? Is this the same TV that you got it fixed by replacing AS15, or it is another TV?

[kumag]

Re: Sony klv-37u300a t-con issue

yes, its the same tv.the last pics posted is the result of both psu and t-con repair.

[budm]

Re: Sony klv-37u300a t-con issue

Oh man. OK, post the picture of what is showing on the screen so we have some idea what is causing the new picture problem.

[kumag]

Re: Sony klv-37u300a t-con issue

photo taken today.. no problem at all..

[budm]

Re: Sony klv-37u300a t-con issue

So it is OK now?

[kumag]

Re: Sony klv-37u300a t-con issue

So it is OK now?

yes it is.. hey master budm, can i post another case? Its about a Viewsonic n2000. it is in totally inverted colors and like a photo negative. whites become black and vice versa..