Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supply

[budm]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

I've attached a pic of my backprobing technique. I'm using a needle point probe and the meter is in autoranging mode. I'm pulling ground with an alligator clip to the chassis.

The service manual is attached to the first post.

Here are the results (copied from above) with pin descriptions.

Thanks for your help.

Power Off
Pin 1 UR13V - continuity beep, then rising to 2.5V
Pin 2 UR13V - continuity beep, then rising to 2.5V
Pin 3 - not wired, UR13V indicated on diagram
Pin 4 - not wired, UR13V indicated on diagram
Pin 5 GND - continuity
Pin 6 GND - continuity
Pin 7 - not wired, GND indicated on diagram
Pin 8 - not wired, GND indicated on diagram
Pin 9 AC_DET - 0V
Pin 10 PS_ON - 1.3V, relay clicks when probed. What does it mean?
Pin 11 BU5V - 4.98V
Pin 12 PNL_ON - 1.4V until pin 11 probed, then 0V What does it mean? It goes to 0V when put probe on pin 11 (BU5V). How did you prbe pin 11 and 12 at the same time?

Power On
Pin 1 UR13V - 12.95V
Pin 2 UR13V - 12.95V
Pin 3 - not wired, UR13V indicated on diagram
Pin 4 - not wired, UR13V indicated on diagram
Pin 5 GND - continuity
Pin 6 GND - continuity
Pin 7 - not wired, GND indicated on diagram
Pin 8 - not wired, GND indicated on diagram
Pin 9 AC_DET - 0V
Pin 10 PS_ON - 0V
Pin 11 BU5V - 4.98V
Pin 12 PNL_ON - 0V

You readings do not make sense.

[budm]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Fluke 113 Utility meter mainly for electrician, it has only 3K Ohms input Z for Voltage measurement, typical meter for electronics works has 10Mega Ohm input Z. At only 3K Ohms input Z this can cause interaction with the circuit that you are trying to measure.
Do you have other digital meter?

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Guys, I appreciate the help.

This is the best meter I own. My other is a much less expensive Greenlee, but I'm sure it will be low-z.

Is it possible to get around this?

[budwich]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

It's a Fluke 113, I'm using a needle point for the backprobe, and an alligator clip to the chassis for ground. The meter is in autoranging mode.

the "vcheck" feature of this meter may be causing some "strange things" to happen during your measurement. As part of its "continuity test" during a voltage measurement, it appears to be allowing some "significant current flow" as part of an "initial resistance type" test. Hence, some of the observations of things "clicking" and such during a voltage measurement.

You might consider selecting a specific test (ie. manual voltage or resistance) instead of "auto" although it may not turn off the "vcheck" feature.

[nomoresonys]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

The 5 dollar Harbor Freight meters are ok for these kind of measurements.

[R_J]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

You likely don't have a problem with the power supply

Power Off
Pin 1 UR13V - continuity beep, then rising to 2.5V <-- with power OFF this is close to normal, should be 0 volts
Pin 9 AC_DET - 0V
Pin 10 PS_ON - 1.3V, relay clicks when probed <-- this is caused by your meter
Pin 11 BU5V - 4.98V
Pin 12 PNL_ON - 1.4V until pin 11 probed, then 0V

Power On
Pin 1 UR13V - 12.95V <-- with power ON this is the correct voltage
Pin 9 AC_DET - 0V
Pin 10 PS_ON - 0V <-- This can't be correct because the power supply is ON according to pin 1
Pin 11 BU5V - 4.98V
Pin 12 PNL_ON - 0V
A proper multimeter would likely show 3.3v on pin 10, PS_ON and would not cause the relay to click when the tv was off.

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

The 5 dollar Harbor Freight meters are ok for these kind of measurements.

Reaaaaaaaalllly.

I have an HF about 20 minutes away, and it's a good day when I've got an excuse to go there.

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

You likely don't have a problem with the power supply

Interesting. So if I go get one of the inexpensive HF meters (that isn't low-z) I should see ~3.3VDC on PD 10 with the set powered on? If so, is it safe to assume that I'm going to get further otuside my abilities very quickly?

It won't be _awful_ if I have to discard or maybe even part out the set. But if it costs $100-200 to keep it online for a few more years, I can live with that.

[R_J]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

According to your first post

the power LED and OPC LED would flash twice, together, about 1/4-second per flash, then the OPC would flash a third time for about 1/4 second, then there would be a 1/4-second pause, and the sequence would repeat.

indicates power led flash 2 times, opc flash 3 times. This indicates a DET_5v error(33) so the microprocessor is not seeing that this voltage is present and gives the error. the fault is on the main board, check if you have +5v on L9601 (near ic9602)

[nomoresonys]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Reaaaaaaaalllly.

I have an HF about 20 minutes away, and it's a good day when I've got an excuse to go there.

Many times they are free with any purchase, check their web site for coupons.

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

My old Greenlee meter might be getting it done. I'll probably still go to Harbor Freight


It's a shame that my Fluke 113 is less than six months old. I should've stepped up to the 117 with the hi/lo impedance capability. Then again, 99% of what I do is single-phase 110VAC and 12VDC automotive, so there's that.

Back to the set --

With PD disconnected, the older meter is showing 3.15V on PD 9 with 10&11 shorted and the mains connected.

With PD connected, backprobing PD 1 comes up with 0 volts with the mains connected and the power off.

Starting to feel like this eBay power supply is a good piece. Things will probably get interesting when I begin to test the original power supply (my OP explains why I'm going to do this).

I'll get at the main board tonight or tomorrow to check for +5V at L9601, using my old meter.

Thanks again so far everyone.

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

L9601 shows 5.08VDC on one pin, and 5.16VDC on the other with the mains connected and the backlight on.

Once the fault occurs, L9601 reads 0VDC on both pins.

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Bump Very much hoping for continued assistance with this set. Thank you

[R_J]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

When the tv stays on for the 30~45 seconds, do you gat a picture? If the error code is correct, it is DET_5V error, since you have 5 volts, that supplies one end of R9740 and the other end connects to ic2002 pin 33 ET_5V. I suspect this voltage (other end of R9740) would be around 3 volts

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Your annotated picture is incredibly helpful. Thank you. Those SMDs are pushing the edge of my eyesight.

The red arrow is definitely +5VDC during operation, then 0VDC after the set shuts off.

The yellow arrow, though, is 0.06VDC during operation. I tested it a half-dozen times.

The old meter which I've used for this purpose is not auto-ranging.

There doesn't appear to be any physical damage to R9740.

Thanks again for any advise you may have to share.

[R_J]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Well that line connects to the processor and if it does'nt change then the error could occur. Check the resistance of that line to ground.

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Hey guys...? From my OP, when the eBay PSU is installed, the set shuts off after 30-45 seconds, and the power LED and the OPC LED flash twice, about 1/4 second per flash, then pause for about half a second, and repeat. Isn't that a 3V error?

[timtrace]

Re: Won't stay powered on - Sharp LC52LE700UN with RDENCA336WJQZ DPS-286AP power supp

Thanks to everyone for the help. The set hit the city’s electronics recycle bin yesterday.