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

[R_J]

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

You would use chassis ground or pin 1 of cn6002, You can find out which resistor it is by puting a probe on CN6002 pin 9 and check to each of the 4 resistors of RB9031. the point that is 0Ω is pin8, now check the other side (pin7) of the resistor to ground, that will check the input point (AE5) of the ic9000

[DXseekerMO]

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

At what ground point should I measure, and on what side of the resistor?

[R_J]

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

When checking resistors use ohm setting, not diode test, in this case the resistors are each 100Ω. If you check from ground to the one that is connected to the ac_off_det line it is likely close to 0Ω to ground
If that line is LOW the ic believes there is a problem with the power supply so it won't allow it to be turned on

[DXseekerMO]

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

Well something on the main is killing the ac_off_det line unless thats normal operation but it does'nt seem likely

That line connects to ic9000 via RB9031 (100Ω)

While tracing down circuits near that resistor array I checked all 4 of them, I believe the reading in diode mode was .120

So I guess that confirms a short in the X-REALITY processor, IC9000?

[DXseekerMO]

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

That makes sense. So there's really nothing to short out on that circuit on the main board but the X-REALITY processor?

EDIT: Just saw your addition to last post, will check schematic

[R_J]

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

Well something on the main is killing the ac_off_det line unless thats normal operation but it does'nt seem likely

That line connects to ic9000 via RB9031 (100Ω)

[DXseekerMO]

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

Voltage comes up to 4.44V with CN6101 detached from PSU

4.44V on the 444th post. You have to be kidding me!

[R_J]

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

If you disconnect CN6101 from the main board, does the voltage come up to 3.3 volts? Somethings killing it

[DXseekerMO]

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

with the red probe on C and black on E it tests open
Reverse the probes and the reading is 1.297

Diode check mode used. Confirmed I tested the right transistor

[R_J]

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

Check Q6402, It must be shorted e-c

[DXseekerMO]

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

Yes it is zero volts

[R_J]

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

Yes I was, but its not so Re check the voltage on PH6302 pin 3, it should be 0 volts

[DXseekerMO]

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

Unplug CN6102 and check it again.

No change in voltage. Maybe you were thinking something on that board was pulling down the AC_OFF_DET volts?

[R_J]

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

Unplug CN6102 and check it again.

[DXseekerMO]

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

Ok so that crispy Q6302 transistor is likely ok, it has 18 volts on the collector which means the power supply is in standby mode. (not on)

So just to refresh, what is the voltage on CN6101 pin 7 (AC_DET_OFF)?

Voltage at pin 7 of CN6101 is .47V

[R_J]

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

Ok so that crispy Q6302 transistor is likely ok, it has 18 volts on the collector which means the power supply is in standby mode. (not on)

So just to refresh, what is the voltage on CN6101 pin 7 (AC_OFF_DET)?

[DXseekerMO]

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

You can check the base voltage on pin 3 of opto PH6301, I'm more interested in the collector voltage and the condition of this crispy transistor.

Pin 3 of opto PH6301, base voltage is zero volts, measured against hot ground
Resistor R6307, collector volts is 18.67 volts measured against hot ground

Q6401??????????????

Thank you for issuing correction, I meant Q6402. I asked if we were transitioning away from Q6301 and more towards Q6402 because budm gave a +1 on the possibility of it being shorted

[R_J]

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

Q6401??????????????


Q6301 is the switch controlled by the power on opto, you could diode check it or check the voltage on the base and the collector
Its collector connects to pin 28 of IC6501

[R_J]

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

You can check the base voltage on pin 3 of opto PH6301, I'm more interested in the collector voltage and the condition of this crispy transistor.

[DXseekerMO]

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

So are we transitioning away from Q6301 and more towards Q6401?

When testing Q6401 is that in diode mode and which probes on the meter go to which pin?