SAMSUNG LN46A650A1FXZA tcon prevented startup

[icekillah]

my SAMSUNG LN46A650A1FXZA wont start it just sits there playing startup signal then shuts off for a never ending cycle, but when i disconnect the tcon board from the main board the backlights will turn on second i plug the tcon board back in it starts cycling again(no backlight) could this be a tcon issue? i would appreciate all input i have a multimeter but everything i checked out seemed to be ok

[budm]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

Good clear picture of the T-CON, check and see if the SMD fuse on the T-CON is blown or not.
Is this the same version as yours?
http://s807.photobucket.com/user/bud...?sort=3&page=1
No bad caps that you can see?
http://s807.photobucket.com/user/bud...ml?sort=3&o=12

[icekillah]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

yup thats my tv! ok i pulled the tcon board off and checked both the fuses(is there any more?) im seeing at least 3 bga chips, i do have a reflow machine but it will probably fail soon after the reflow. i replaced alot of caps on the psu and already bought a new psu and main board as i believed a bad tcon board would not have the ability to stop a tv from starting.

pics of the tcon board are here:

http://s1088.photobucket.com/user/ic...y/?view=recent

[tom66]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

Connect the T-con back up but remove the ribbons going from the T-con to the LCD panel. Does the TV still do the boot loop?
I had a 40" B650 Samsung with a boot loop due to bad T-con board, replacing T-con fixed it.

[icekillah]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

yup tcon hooked up with ribbon cables disconnected still boot loop. I saw your youtube video tom and its doing exactly that (minus the psu giving bacvklight on its own), already ordered a new tcon board anyone need a psu or mainboard for this tv? i will sell for dirt cheap to a member of this forum as soon as i can test it and make sure its a good board.

[tom66]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

I know the main boards for this have a few problems. Once you get your TV fixed, test both boards (especially HDMI, and digital tuner if it has one.) Then you can offer the board for sale on eBay and genuinely say you've tested it (unlike most sellers.)

[icekillah]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

just popped a tcon board in today and its working fine right now

[Electron4444]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

Hi all, I am working on a Samsung LN46A650A1FXZA 46 inch LCD TV.
The TV has the same start loop problem as icekillah has. It starts and then shuts off and then repeats & repeats etc. My TCON board is the same as the picture posted by icekillah too.

Searching this site there are many complaints of bad capacitors. A visual inspection did not show any bulges or leaky ones. I removed the power supply board and checked all the caps for a high ESR. All caps where well within acceptable values. Thus, I did not replace any of them. I then powered the supply separately with nothing else connected using my isolated AC supply. The standby voltage was 5.1 VDC. I then jumped the standby voltage to the On/Off input on the card. The relay clicked and the Run 5.1 and 13.1 came up. The 13.1 was a little high at 13.5 V. I then checked all the supplies for ripple and it was down in the scope leads noise levels.

I put the power supply back in the TV. The 13.1 and 5,1 came up when I turned on the power using the remote control. It also would turn the set off. The 13.1 was 13.65 and the 5.1 was 5.17 and the backlight came on. After a few seconds, the 13.1 dropped to 12.65V and the looping began.

I disconnected the Panel from the TCON and the same power start up loop continued. I then disconnect the TCON from the main board and the loop stopped and the set stayed on with the 13.1 at 13.65.

Since the power loop goes away when you disconnect the TCON, you would imagine that it was bad. But the drop in the 13,1 from 13.65 by over a volt to 12.65 makes the power supply or main board a little suspicious. Although the TCON could be loading the supply.

Seeing that I am a retired EE and fixing electronics has been a life long hobby, I decided to bug the TCON for obvious discrete component fails. Both fuses are OK, I found that transistor Q2811 was shorted Collector to Emitter, Base to each bugged OK as diodes. Not having a schematic makes it a little tougher. But it looks like Q2811 is a NPN and I have seen bigger ants than it. The emitter appears to be normally connected to ground. I removed Q2811 and the short between the collector and emitter pads remained. Tracing the board it appears the collector is connected to R660_OP and is “0” ohms os marked and to R662_OP which appears to have a diode around it with 5 ohms and 200 ohm readings marked 010. The other end of these resistors go to through holes on the board. The collector pad then continues on the PC board to a through hole by C532 where it gets lost. Attached is a picture of a section of the TCON containing the area I am working on.

If any of you have a schematic, I would appreciate it if you could tell me if my bugging is correct and where Q2811 collector, R660, & R662 are connected. If the collector goes to the large BG IC with the heat sink, it appears the TCON is toast.

The other problem I have is the part number of the TCON itself. The two markings are E2347JBI0JC3 – 025059 on the label and FRCM_TCON_Vo.1 on the PC board. The ones I have seen for sale mention a LN94etc. number. There are no other P/N markings on the board. Is this number familiar to anyone.

Thanks for any help you can give me.

[budm]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

Which one of these T-CON matched your board?
http://www.shopjimmy.com/catalogsear...SUNG+LN46A650A

[Electron4444]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

Which one of these T-CON matched your board?
http://www.shopjimmy.com/catalogsear...SUNG+LN46A650A

This one Samsung LJ94-02347J (FRCM_TCON_V0.1) T-Con Board

[Electron4444]

Re: SAMSUNG LN46A650A1FXZA tcon prevented startup

Sorry, I have a typo on the transistor ID.

It should be Q2822 and R660 making is 0 not 0s