KDL-46S4100 takes time to turn on then shuts off

[Pioneerx01]

I got my hand on Sony KDL-46S4100. When I press power button it takes ~15 seconds to turn the lamps on (not sure if that is normal or not). Nothing shows on the panel, but the lamps are on. No reaction if I press/change menu, input, volume or channel. 30 seconds after the lamps turn of the TV shuts down and goes to stand by with red LED. No blink codes, apparently this model does not communicate with its owners

The PSU looks OK and voltages check out. The 6.5V is a little high at 7.15V, but rest is fine.

I have found one article online that suggest that the main board is the issue. Anyone can provide any more info?

Thanks

[Pioneerx01]

Re: KDL-46S4100 takes time to turn on then shuts off

This is a little bad diagnosing, but it appears the the main boards are relatively expensive for this model, so it may just be a common problem. Thoughts?

[Hamie]

Re: KDL-46S4100 takes time to turn on then shuts off

Check both sides of the t-con fuse you should get 12 volts.
Need to see if the T-con is getting anything from mainboard.

The mainboard is sending the ps-on signal to the power supply as its turning on the backlight

[Hamie]

Re: KDL-46S4100 takes time to turn on then shuts off

Pictures always help.

[vinceroger69]

Re: KDL-46S4100 takes time to turn on then shuts off

The training manual in this post may help you.
https://www.badcaps.net/forum/showthread.php?t=31508

[Pioneerx01]

Re: KDL-46S4100 takes time to turn on then shuts off

T con fuse reads OK. 12V on both sides.
I will look through the manual next, thanks for the link.

[Pioneerx01]

Re: KDL-46S4100 takes time to turn on then shuts off

I looked through the manual, it is great, where can I get more for other models?

While looking over the manual I went with no video problem (flowchart E, page 37) and I am at a last step where I have to "Check LVDS cable Video Signal Levels CN2501/pins 1,4,8,14,28 & at TCON Brd" however I do not have an oscilloscope. Based on the results it is the panel or the main board (board A)

On page 24, there is a table which tells me that video signals should read about 30mVAC. I do not have that sensitive volt meter on AC, but when I do measure them I get ~2.4VAC; which is over the norm. Should I take that as "bad level" and follow the flowchart E (pg 37) to assume it is the main board (board A)?