Sony KDL-55EX620, no stand-by volts from one bad resistor?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

If I am reading the diagram right, if voltage is present at pins 1 and 2 the LED inside the opto should illuminate and close the circuit on pins 3 and 4?

Since 3.49V is already at pin 3 and this is the specified voltage for that circuit, shouldn't jumping pins 3 and 4 activate the AC_OFF_DET circuit if the opto is bad?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

G6 board.
Please pay more attention, I spend lots of time providing you with service info. Schematics, Training manual, etc.
We are up to post 46 now.

Yes, I do tend to get the cart before the horse occasionally. but I do try to accept my mistakes humbly

[budm]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

G6 board.
Please pay more attention, I spend lots of time providing you with service info. Schematics, Training manual, etc.
We are up to post 46 now.

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

Your power supply board in your 55" is G6 board, look at page 35 for G6 schematic which is for your TV.
G5 power supply board is not used in your TV, G5 uses Q6405 in the AC_OFF_DFET circuit.
Look at you board, the service manual and then match them up to what you are troubleshooting.
Service manual page 7 shows what boards are used in your TV!

I almost made that mistake, I am looking at the G6 board schemo on page 35

Ahhhh, crap.....I was on the wrong page, but the circuit looks identical, save for nomenclature

Now on page 35

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

I see that, it traces to pin 3 of PH6302 which has zero volts. Pin 4 has 3.49V. If I am reading the diagram right it looks like pin 3 is the supply line for Q6402 which looks like no volts at pin 3 = transistor Q6402 doesn't turn on?

Also pins 1 and 2 of PH6302 have 18V present, hot ground used

Maybe I should ask how the electricity flows through an opto. I'm guessing there's an electrically conductive photocell in there that when the LED's inside light up it results in electrical flow through pins 3 and 4?

[budm]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

Your power supply board in your 55" is G6 board, look at page 35 for G6 schematic which is for your TV.
G5 power supply board is not used in your TV, G5 uses Q6405 in the AC_OFF_DFET circuit.
Look at you board, the service manual and then match them up to what you are troubleshooting.
Service manual page 7 shows what boards are used in your TV!

[budm]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

"On page 35 of the service manual I traced the AC_OFF_DET circuit back to that crispy looking transistor Q6405"
You need to look at the schematic again, that is not what is shown in the service manual I provided. We need to get correct info first.
You need to trace the circuit from the AC_off_det pin cn6101 pin 7 back toward the front end.

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

You understand how transistor work, correct?

Maybe you should explain it to me....apparently I have something mixed up in the bean.....

It looks like the single lead side is supply voltage, the side that goes to ground switches the other side on so electricity can pass?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

The problem is no AC_OFF_DET volts at CN6101

[budm]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

You understand how transistor work, correct?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

Sorry, PH6302

[R_J]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

I just used ph6101 as an example, which opto are those voltages for?
Pins 1 & 2 are the same voltage so the internal led will be off, so the optos output transistor will be open.

So whats the problem again?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

THANK YOU R_J!!!!! That got me straightened right out!

Pin 4 reads 18.6V Hot ground
Pin 3 reads 0V Hot ground
Pin 2 reads 4.45V Cold ground
Pin 1 reads 4.45V Cold ground

That means voltage IS present after the opto?

On Transformer T6201 there is main cap value voltage at pins 1, 2 and 3 and no volts on 5 and 6, hot ground used.

[R_J]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

Thats why, the power supply has HOT ground and COLD or chassis ground, you need to use HOT ground when checking voltages on the primary side.
HOT GROUND would be the [-] connection of C6521-C6526
Lets take PH6101 for example, pins 1 & 2 are on the cold side so use chassis to measure the voltage. Pins 3 & 4 are on the HOT or Primary side so you must use C6521 [-] for ground (hot ground)

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

Chassis.

There is zero volts at leg 5 of transformer T6201. If I'm reading the schematic right this is significant?

There is no voltage present on that whole side of the transformer.

[R_J]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

When you are checking these voltages on the opto, what ground are you using?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

So I tested leg 1 of PH6301 and found 4.45V steady

I then tested leg 3 of PH6301 and had no volts

Just now I tested leg 4 of PH6301 and have 0V, but I do have 3.49V at leg 4 of PH6302

This means pin 26 of IC6501 has good output to the opto and the opto is not passing the signal through to transistor Q6405 to switch on the AC_OFF_DET voltage?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

On page 35 of the service manual I traced the AC_OFF_DET circuit back to that crispy looking transistor Q6405 and opto PH6301 and on to IC6501, pin 26. That IC must switch/make 3.3 or maybe 5V or something?

I could test to see if the voltage is there, but that IC is on the other side of the board. Is there a test point on the top side of the board for this voltage?

I suppose I could test that leg of Q6405 and leg 3 of PH6301 as well if I can find a test point?

[DXseekerMO]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

Early in the diagnostic the orange light blinked two times, pause, two times. When POWER_ON voltage was present it was staying on all the time. It no longer illuminates at all.

The missing AC_OFF_DET power looks like it comes from the G board. That would seem to make the most sense since AC is on that board. I guess that means I have a bit more detective work to do there? And if I am understanding this right it looks like the main board has a failure as well?

Or is the processor denying POWER ON because the AC_OFF_DET voltage is absent?

[budm]

Re: Sony KDL-55EX620, no stand-by volts from one bad resistor?

AC_OFF_DET should be 3.3V for normal operation, see service manual PDF page 35. Also see AZ2-F training.
BTW, are you getting any error blinking codes?