Re: sharp lc32d42u power supply - DPS-178APA
"Since all the other voltages are being supplied by the power supply, and you say the rest of the tv is working and the fault is on THIS power supply. Simply forcing on Q7926 will not be an issue and the tv will work because you tested proved it with the other power supply correct?
Correct.
Can I assume that this resistor test can be done without the "load" of the rest of the TV?
If so, I'd bring it to my friends shop week after next and do it there.
If not I'll get a couple 1ks...
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Re: sharp lc32d42u power supply - DPS-178APA
"Shorting Q7907 collector to ground will force the PNL5V ON. "
Something has changed here. The blue power LED upfront no longer lights.
I just shorted the C of Q7907 to gnd. PNL POW (P4 of PD) OV.
P3/4 of PE at 0V.
Perhaps Q7907 was failing or am I coming to the wrong conclusion?
Other Voltages are all still correct.
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Re: sharp lc32d42u power supply - DPS-178APA
PE
pin1=UR6V - 5.77
pin2=gnd
pin3=PNL5V - 0
pin4=PNL5V - 0
pin5=gnd
pin6=gnd
pin7=UR10V - 10
pin8=UR10V - 10
pin9=gnd
pin10=gnd
pin11=UR13V - 12
pin12=UR13V - 12
PD
pin1=PS-ON - 3.02
pin2=AC_DET - 3.07
pin3=gnd
pin4=PNL POW - 0
pin5=BU5V - 5
pin6=gnd
LA
pin1~5=24V yes
pin6~10=gnd
when I short Q7907 collector to ground, the red LED annunciators on...
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Re: sharp lc32d42u power supply - DPS-178APA
trying to figure out the location.
Is there any indication in the SM pcb drawings that would indicate this heat sink. The ref point might help localize the chip.
[ATTACH]206651[/ATTACH]
Or remove it that I might have a look at whats hidden.Re: sharp lc32d42u power supply - DPS-178APA
trying to figure out the location.
Is there any indication in the SM pcb drawings that would indicate this heat sink. The ref point might help localize the chip.
[ATTACH]206651[/ATTACH]
Or remove...Last edited by metropical; 02-05-2020, 05:35 PM.
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Re: sharp lc32d42u power supply - DPS-178APA
IC2007, R2004 and C2024 seem to be on the B-side (trace).
Are there test points on top I can access?Last edited by metropical; 02-05-2020, 01:33 PM.
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Re: sharp lc32d42u power supply - DPS-178APA
Took some doing but there is always a piece of sacrificial Cat 5.
I took a piece of wire from ground to the Q7907 collector.
With TV on or off, 5v.
So Q7926 is good?Last edited by metropical; 01-30-2020, 10:27 PM.
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Re: sharp lc32d42u power supply - DPS-178APA
I'll have to find me some better gator clips. It's pretty tiny on that Q.
But, unplug PE on the power supply and with the tv on, check the voltage on J7915. It is 0 volts.
This might take me a few days to find leads out here in the boonies.
Prolly pick some up in the city next week.
I'll be in touch.
Thanks very.
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Re: sharp lc32d42u power supply - DPS-178APA
Can that be done with the power board out of the TV, or does it need to be done under "load"?
If that isn't the issue, what might other possibilities be?
I would think it's the power board, as, like I said, I swapped supplies with another of the same and the other TV that was dead was fine....
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Re: sharp lc32d42u power supply - DPS-178APA
I have UR13v PE, pins 11,12 showing 12v.
UR10v pins 8,7 is good.
Funny, my SM doesn't even list Q7907 or C7921. But I did find Q7907 on the PCB.
Ah, I see, my book doesn't have the PS parts list .... near as I can tell
Can it be checked in circuit or only lifted?Last edited by metropical; 01-30-2020, 05:48 PM.
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Re: sharp lc32d42u power supply - DPS-178APA
OK. But as I said. 2 of the same TV. Swapped out the PS board and all is well.
.
Something else occurs to me. That voltage, Pin4 on plug PD, isn't steady 0v. It jumps around too fast to see the top, stand-by or powered.
Unlike the 5v pin which is quite steady.
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