Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

[DXseekerMO]

So in an attempt to avoid further confusion this is an extension of this thread: https://www.badcaps.net/forum/showthread.php?t=73120 I made such a mess out of this one that I felt to avoid confusion and back-tracking through 8 pages of thread I thought I should just start over with what I have right now.

BACKGROUND:

This TV is the victim of a confirmed over-voltage event. I bought this Sony and a TCL TV from the same place, both appearing dead. I replaced the power supply in the TCL which fixed that TV.

To this point, fusible resistor R6201 was replaced for being open and IC6201 was replaced due to a 170ohm short across the S and D pins. After their replacement, stand-by volts would increase from about 3.2V to 4.45V when CN6101 (to the main board) was detached. From this it was suggested IC6251 is replaced, which I just did 30min ago.

There is still no stand-by light, however stand-by voltage of 3.25 to 3.3v is now at CN6101.

VOLTAGES CN6101:


PIN no…………………PIN ID…………………….Volts……………………..Volts CN6101 detached
1……………………..POWER_ON…………………0v………………………………………..0v
2-5………………………NC
6………………………..BL_ERR……………………..0v………………………………………..0v
7…………………….AC_OFF_DET………………0.46v…………………………………..3.21v
8………………………T-CON_ON………………….0v…………………………………………0v
9……………………………GND
10………………………STBY_3.3………………..3.26v ……………………………………3.3v
11……………………..AU_GND
12……………………..AU_12V……………………..0…………………………………………0
13……………………..AU_GND
14……………………..AU_12V……………………..0…………………………………………0
15, 17, 19, 21, 23, 25, 27……GND
16……………………..REG_12V……………………0…………………………………………0
18……………………..REG_12V……………………0…………………………………………0
20………………….BOR_ASU_12V………………0…………………………………………0
22………………….BOR_ASU_12V………………0…………………………………………0
24………………….T-CON_VCC12V…………….0…………………………………….……0
26………………….T-CON_VCC12V…………….0…………………………………….……0
28………………….T-CON_VCC12V…………….0…………………………………….……0

So there still looks to be a problem on both POWER_ON and AC_OFF_DET lines.

[nomoresonys]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

Do you get the proper voltages with a force on of powerboard or maybe you already tried it?

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

Do you get the proper voltages with a force on of powerboard or maybe you already tried it?

No, haven't tried to force the power supply on. I'm not too sure about a force-on after an over-voltage event....I'd hate to fry other stuffs and have to buy a power board for this, especially when I see AC_OFF_DET raise up when the main board is disconnected. I hope I'm wrong about that being a sign of a main board problem.

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

It does appear according to the training manual, AC_OFF_DET should be 3.3 volts in standby mode with main connected
I see that cn6102 also has the AC_OFF_DET line going to it so it could be that the main IS loading down that line
What I might try is take a 500Ω - 1k resistor and with main connected, connectthe resistor between standby 3.3 & AC_OFF_DET and see if the standby led comes on.
Also monitor the voltage on the AC_OFF_DET line when doing this to see if it still drops

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

I would expect AC_OFF_DET to go to 3.3 with main disconnected, This is because there is no current being drawn so no voltage drop across R6403 and R6404 so you measure 3.3 standby

I'm getting ready to sound like a broken record. I can't believe it. Yet again here's another power supply with up-and-down voltages. This time it's on PIN5 (source) of IC6201, from 140 to about 190v best I can tell with the way its swinging!

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

Its likely your meter that's picking up the high voltage pulses, Check the voltage R6201
The standby circuit is working, why are you even checking that ic?

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

Its likely your meter that's picking up the high voltage pulses, Check the voltage R6201

163.7v on both sides of R6201

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

So its your meter that's picking up the switching pulses from the ic.
as for the AC_OFF_DET.
IC6501 pin 26 should be high (same as VCC pin 23 volts) with normal a/c connected. This means the same voltage will pins 1& 2 of PH6302, so the led will be OFF
With PH6302 led off, the output 3 & 4 will be open. Q6402 will be turned off so the 3.3 volts from R6403 will appear on R6404 and also on the AC_OFF_DET line
My guess, main board is loading the AC_OFF_DET

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

So its your meter that's picking up the switching pulses from the ic.
as for the AC_OFF_DET.
IC6501 pin 26 should be high (same as VCC pin 23 volts) with normal a/c connected. This means the same voltage will pins 1& 2 of PH6302, so the led will be OFF
With PH6302 led off, the output 3 & 4 will be open. Q6402 will be turned off so the 3.3 volts from R6403 will appear on R6404 and also on the AC_OFF_DET line
My guess, main board is loading the AC_OFF_DET

Yes, so I pulled the main board to see if there may be an answer.

The only suspect is a 14Kohm reading across the circled cap. One side of it is connected directly to the AC_OFF_DET pin of the connector next to it.

EDIT/ADD: I traced the whole AC_OFF_DET circuit on both sides of the board. The choices appear to be this cap, a resistor group (that appears to test good) and the X-REALITY processor.

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

The cap is likely C6101, The resistor network is RB9031 (4x100Ω) Pin 8 connects to AC_MON (AC_OFF_DET), Pin 7 goes to ic9000(ae5)
with the main connected, check the voltage on:
PH6302 pin 4
then check the voltage on Q6402 e,b,c

I would'nt think 14k would load the 3.3 volts that much, check that R6403 & R6404 on the power supply are good

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

The cap is likely C6101, The resistor network is RB9031 (4x100Ω) Pin 8 connects to AC_MON (AC_OFF_DET), Pin 7 goes to ic9000(ae5)
with the main connected, check the voltage on:
PH6302 pin 4
then check the voltage on Q6402 e,b,c

I would'nt think 14k would load the 3.3 volts that much, check that R6403 & R6404 on the power supply are good

PH6302 PIN4 checks at 3.28v

Q6402 is on the bottom side of the board. How can I check this with the main hooked up? There won't be any ground screws in the power supply.

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

You don't need the ground screws it is ground via the cables, place something under it so it won't short to the chassis anywhere.
You could also measure PH6302 Pin3 from the top, that would give an indication of the q6402 base voltage

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

You don't need the ground screws it is ground via the cables, place something under it so it won't short to the chassis anywhere.
You could also measure PH6302 Pin3 from the top, that would give an indication of the q6402 base voltage

Q6402 base: .49v Emitter: 0v Collector: 0v, checked directly on the terminals.

EDIT/ADD: R6403 and R6404 check good.

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

Is q6402 shorted e-c? I would think there should be 0 volts on the base. and 3 volts on the collector
PH6302 should be off ie: 0 volts across pins 1 & 2
try shorting the base to emitter/ground and see if you get 3 volts on the collector

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

Is q6402 shorted e-c? I would think there should be 0 volts on the base. and 3 volts on the collector
PH6302 should be off ie: 0 volts across pins 1 & 2
try shorting the base to emitter/ground and see if you get 3 volts on the collector

Before I do this I wanted to make sure of the pinout. This transistor is marked N1.

If viewed with the single terminal at the top of Q6402 are the pinouts E (lower left), B and C (lower right)? See pic below:

[budm]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

The one you mark as E is actually B.
The one you mark as C is actually E.
The one you mark as B is actually C.
That is the typical pin out for that form factor:
I.E. https://cdn.badcaps-static.com/pdfs/...8468ce7268.pdf

[DXseekerMO]

NOT fixed

Today I replaced the power board in this TV. Unfortunately the TV does not work. Looks like the main board is no good.

Stand-by voltage and AC_DET voltage was present on the replacement board. Stand-by was constant but AC_DET dropped to .46v with the main board plugged in, and raised to normal voltage when unplugged.

On to source a main board.

[Diah]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

sorry mat. you just following your believe... budm RJ. suggest the correct way of pin labeled and powering the PSU
over all Sony / LG Main boards there are ICs of Power detectors which they watch 12 24 etc. volts and notify main processor ( voltage are here ) so it keep on and run the reset of the sets. if they are missing the AC DET go high.
you need to disconnect MB from PSU first and as suggest by RJ force PSU to turn on and get the rest of voltage,,, to be sure PSU 100% okay, then plug the MB and check, if there are still issue it mean MB had issue.

[R_J]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

There are a bunch of small fuses on both sides of that main board, it might be worth checking them, you never know, I see at SJ there is an update to do after replacing the main board

[DXseekerMO]

Re: Sony KDL-55EX620 stand-by present, no stand-by light, AC_OFF_DET @.47V

sorry mat. you just following your believe... budm RJ. suggest the correct way of pin labeled and powering the PSU
over all Sony / LG Main boards there are ICs of Power detectors which they watch 12 24 etc. volts and notify main processor ( voltage are here ) so it keep on and run the reset of the sets. if they are missing the AC DET go high.
you need to disconnect MB from PSU first and as suggest by RJ force PSU to turn on and get the rest of voltage,,, to be sure PSU 100% okay, then plug the MB and check, if there are still issue it mean MB had issue.

This I will do, but I was looking back in the thread and the only thing I see for forcing anything on is the 500-1000ohm resistor between STBY3.3 and AC_OFF_DET to see if the stand-by light turns on.

There are a bunch of small fuses on both sides of that main board, it might be worth checking them, you never know, I see at SJ there is an update to do after replacing the main board

This I will also do, never thought of this. Am I missing the part of this thread where you talked about how to force on the PSU?

The PSU came from a place called TVPARTSTODAY in Evansville IN. Word on the street is their parts go out the door as described and in good working order. I suppose anyone can make a mistake tho...