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Old 05-11-2022, 08:49 PM   #1
Crystaleyes
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Default Sony KDL-46EX505 No T-con Voltage

Hi all,

been asked to look at a friends old Sony which turns on ok, changes channels and has backlight and volume control etc. yet just displays grey, with a few streaky lines across the screen.

A quick test revealed that the voltage across the T-Con cable connector(CN6151) on the PSU (G2) was missing, although the 3.3v 'T-CON_On' and 'T-CON_Vcc12v' were present at the connector which links to the main board (CN6150).
As they live some distance away I took the PSU with me to see where the problem might lie.



I'm presuming that the 3.3v needs to be connected to both the 'POWER_On' and 'T-CON_ON' in order to for the area in question on the board to stay 'live'?
There is not a lot of circuitry between the two connectors, with a FET and a couple of transistors after the secondary of a transformer, but my concern is whether the PSU might be damaged with no load?

I'm not a TV tech but want to know if there is likely to be any problem if I power the board up without any load?

Enclosing the schematic and a couple of photos of the suspect area if anyone is interested
Attached Images
File Type: jpg 20220512_035458.jpg (990.5 KB, 15 views)
File Type: jpg 20220512_035530.jpg (1.30 MB, 13 views)
Attached Files
File Type: pdf sony_1-881-519-11_delta_aps-260_psu.pdf (1,013.0 KB, 5 views)

Last edited by Crystaleyes; 05-11-2022 at 09:04 PM..
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Old 05-12-2022, 12:39 PM   #2
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Default Re: Sony KDL-46EX505 No T-con Voltage

As a load, you can use car incandescent lamps, then checking the power supply will be more informative
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Old 05-12-2022, 01:00 PM   #3
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Default Re: Sony KDL-46EX505 No T-con Voltage

Quote:
Originally Posted by Crystaleyes View Post
As they live some distance away I took the PSU with me to see where the problem might lie.

I'm presuming that the 3.3v needs to be connected to both the 'POWER_On' and 'T-CON_ON' in order to for the area in question on the board to stay 'live'?
you are correct about how to run the PCB as stand alone to have t-con 12 and other V to MB socket... but i think you took the wrong boards with you... the issue much at MB. or T-CON or panel.
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Old 05-12-2022, 09:59 PM   #4
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Default Re: Sony KDL-46EX505 No T-con Voltage

Quote:
Originally Posted by kasfamily View Post
As a load, you can use car incandescent lamps, then checking the power supply will be more informative
Yes. Nice one.

Obvious really, but still didn't enter my head,

thanks
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Old 05-12-2022, 10:03 PM   #5
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Default Re: Sony KDL-46EX505 No T-con Voltage

Quote:
Originally Posted by Diah View Post
you are correct about how to run the PCB as stand alone to have t-con 12 and other V to MB socket... but i think you took the wrong boards with you... the issue much at MB. or T-CON or panel.
You think so?

Does the T-CON_ON signal not come to the PS board from the main board? Then surely it is the PSU board which powers the T-CON board?

Haven't had time these last couple of days but intend to power up the PSU and see what readings come up.
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Old 05-12-2022, 10:50 PM   #6
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Default Re: Sony KDL-46EX505 No T-con Voltage

No you don't need a load to check unless you suspect it can't put out the required current.
T-con are most often powered through the ldvs cable from the main to the t-con on one side of the cable.
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Old 05-13-2022, 07:17 AM   #7
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Default Re: Sony KDL-46EX505 No T-con Voltage

Quote:
Originally Posted by dskall View Post
No you don't need a load to check unless you suspect it can't put out the required current.
Thanks.

Quote:
T-con are most often powered through the ldvs cable from the main to the t-con on one side of the cable.
And I'm sure that there is some power in this cable as the T-CON board gets warm.
There is a second thicker wired cable from the PSU to the T-Con and it is this which has no power.
Hopefully should have time today to connect it up and test it further
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Old 05-13-2022, 09:30 AM   #8
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Default Re: Sony KDL-46EX505 No T-con Voltage

yep, when dealing with distance, always take the whole tv whenever possible.
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Old 05-13-2022, 09:47 AM   #9
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Default Re: Sony KDL-46EX505 No T-con Voltage

It always helps to have good pictures.
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Old 05-14-2022, 08:55 PM   #10
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Default Re: Sony KDL-46EX505 How to test a T-CON board?

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Originally Posted by dskall View Post
It always helps to have good pictures.
For sure, but only having the one board with me didn't help.

Anyway, fired up the board and the T-CON connector voltages are present and correct at 12v, so it would indeed appear that I am looking at the wrong board.

I'll head back up to the TV in the next few days, but are there specific voltages which can be measured on the T-CON board to confirm whether or not it is working?
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Old 05-14-2022, 09:43 PM   #11
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Default Re: Sony KDL-46EX505 No T-con Voltage

vgl, vgh, vcom, vcc's
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Old 05-24-2022, 08:01 PM   #12
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Default Re: Sony KDL-46EX505 No T-con Voltage

Still haven't got back to the TV but considering there are a multitude of lines across a grey screen, judging by what I can find, it may be that the VDA/VSource voltage is missing.

If tht does turn out to be the case, any idea what might cause that to fail?
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