Sony KDL-46EX500 2 blinks, then 6 blinks

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

The 4 zener seem to be OK ( but without dessoldering them)

[dick_barton]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

The fault does appear to be on your inverter board.

If pin 6 is more positive than pin 5 then the output pin 7 goes to 0V.

If pin 5 is more positive than pin 6 then the output goes towards VCC

So that IC does appear to be working.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Yes, thank you !
I'm working on a rough schematic of the inverter board...

[dick_barton]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Run the soldering iron over all the transformer joints on the inverter board.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Run the soldering iron over all the transformer joints on the inverter board.

I already did that ... all is good.
I'll check again anyway

[dick_barton]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Is there a poor solder connection on pin 5 of U1 or it is just the photo.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Is there a poor solder connection on pin 5 of U1 or it is just the photo.

No, it is ok, it is just the photo.

But I see strange results for the zener diodes ZD104 and ZD107

What I read on them (very hard !) is "95" or "U5"

When I test them with the T7 (no desoldered), I get:

7.18V___ on the ZD104 and
23.3V___ on teh ZD107.

When the TV is on, I measure :
12V on both on them !

I think I'll try to desolder them tomorrow... because I have to leave now.

Many many thanks !!!

[dick_barton]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

May be worth checking Q101 with your tester.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Hello,

May be worth checking Q101 with your tester.

I tried with bad results. It is a 702 Mosfet, and the tester only sees the diode between source and drain, but nothing on the gate...

Is it faulty or is it due to the fact that it is soldered...

Before desoldering ZD104 and ZD107, I'd like to know their type.
And I did not find that on Google...

What a mess

https://www.badcaps.net/forum/attach...1&d=1618046449

[dick_barton]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

The 702 mosfet appears to readily available on-line. You really need to lift it out of circuit to test it.

Do you have an LED tester which can test zener diodes?

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

I do not have a LED tester specifically, but my T7 tester does test zener...

[nomoresonys]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

If you have difficulty de-soldering components, check some youtube videos and practice on some junk boards, then take those components out of circuit to test. I know it seems like the long road but it beats trying to guess if they are ok.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Yes ! Thank you very for your support
I’ll do that !

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Thank you very for your support

Thank you very MUCH for ...

[kasfamily]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

ZD104 and ZD107

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Thank you kasfamily. So 24V zeners .. I'll continue my tests.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

I'm back.
The TV works again !
After new tests and more reflexions, I became pretty sure that the problem came from the powerboard card.
And I had the chance to find a second hand powerboard card on eBay for 45€ in Italy.
I received it today, and the TV works perfectly now :-)
I would have loved to repair it at component level, but I was lacking of information (and of personal technical knowlegde).
So, as it may interest someone in the future, I made measurements on this working unit :

on CN 6150:

STBY_3.3V__________3.3V
AC_OFF_DET________3.3V
POWER_ON_________3.3V
AUDIO_12V_________12.77V
REG_12V___________12.75V
BL_ERR____________0.065V
BL_ON_____________3.2V
DIMMER____________1.965V
T-CON_VCC12_______12.73V
T-CON_ON__________3.3V

on CN 6702:

LD________12.06V DC
FB________0.15V AC

on the cathodes of the six double diodes connected to the 12 transformers on the balancer board, I get 1.5 V

Voilà

Thanks to all the people on this forum for the tons of infos I got, and especially to nomoresonys, dick_barton and kasfamily

[dick_barton]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

I'm glad you got there in the end. Especially since I was convinced it was an inverter fault.

[chrisl32]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Especially since I was convinced it was an inverter fault.

And you are probably right, because the inverter is integrated in the powerboard card, and I suspect that this part is faulty.
The clue for me was that the T6801 transformer was buzzing in the audible range, it should not have as it should be working at high frequency...50KHz or so ...

[budm]

Re: Sony KDL-46EX500 2 blinks, then 6 blinks

Glad to see you got it fixed.
BTW, the long green board connected to the CCL's is called Balancer board, it is for evenly distributing high Voltage from Power supply/Inverter board combo to the CCFL's. If one or more lamp fail/bad it will cause unbalance situation which then the error signal is created.

See attach PDF to learn how the Backlights function, see page 44 for how your backlights topology.