LCC5255U going to error standby

[jkomorek]

I have a LC-C5255U which does not power on.

When I first got it home and turned it on, the power light flashed twice and the OPC flashed twice as well. I tracked down the service manual for the TV and it states:

DET_D3V3 (pin 36) failure (L). D3.3V is not applied.
If error is detected during operation, error standby is activated by polling.277bp

I took the Power supply off so that I could examine it for burn marks, etc. After not seeing anything, I put it back on, turned on the TV and now I am getting the power light flashing three times and the OPC flashing once, which according to the service manual means:

Initial communication from the main CPU is not received.
(After canceling the reset, request for the monitor model No.
is not received.)
Communication line failure or main CPU start-up failure.

If I unplug the inter boards I continue to get the same main CPU start-up failure.

I have attached a few photos of the power supply as a starting point, please let me know if any other photos would be helpful.

[jkomorek]

Re: LCC5255U going to error standby

I just tried forcing on the power supply by holding Channel Down and Volume Up. The result was that no backlights came on, the TV just sat there looking dead other than a solid power light.

[jkomorek]

Re: LCC5255U going to error standby

So, any suggestions on where to start? The service manual speaks of checking debug statements for the main CPU; however, I cannot find any information on where these debug statements exist or how to access them.

Where can I start troubleshooting this issue?

[jkomorek]

Re: LCC5255U going to error standby

bump

[martyparish]

Re: LCC5255U going to error standby

I have a Delta power supply in my VIZIO. It's got bad caps. I tried the "hair dryer" trick and it temporarily got it up and running.

Do you have a multimeter? Test all pins on the connector that has 12 pins and report the findings. Test once in while in stand by and then again while trying to power it on.

[budm]

Re: LCC5255U going to error standby

Any link to service manual? Is this Sharp TV?

[jkomorek]

Re: LCC5255U going to error standby

Any link to service manual? Is this Sharp TV?

LC-C5255U is a Sharp TV, yes. I do have the service manual as mentioned in my previous posts. I can provide you a link if that is what your intention is.

The service manual states that I should check the "Debug Statements"; however, I do not know where to find these and cannot find any reference for them elsewhere.

[jkomorek]

Re: LCC5255U going to error standby

I have a Delta power supply in my VIZIO. It's got bad caps. I tried the "hair dryer" trick and it temporarily got it up and running.

Do you have a multimeter? Test all pins on the connector that has 12 pins and report the findings. Test once in while in stand by and then again while trying to power it on.

Thanks for the post. I will take the readings when I get home and post them. The board clearly stated where the 5v standby and 12v for the inverter boards were supposed to be, and I confirmed that the 5v was fine (I didn't bother with the 12v since a failure signal was cutting power anyway)

What I couldn't figure out was which pin supplied the 3.3v which the initial error message was complaining about.

I just learned about 'the hairdryer test' and will give that a shot as well.

[selldoor]

Re: LCC5255U going to error standby

Yes we need to see the service manual - debug statements ,I believe, are what the service engineer can see when he connect up his laptop to the tv- so not really for your use. A better lit (But without flash) picture of the full board may help. If the boards are off we also need to see the backs, preferably in the same orientation as the fronts

[budm]

Re: LCC5255U going to error standby

I need to see the service manual so I can look at the diagram and find out how and where the voltages are generated.

[jkomorek]

Re: LCC5255U going to error standby

Here is the service manual: https://docs.google.com/file/d/0B3xF...JOMWhwYkU/edit

[budm]

Re: LCC5255U going to error standby

OK, I studied the diagram, see the sch where the D3.3V is generated as I had redlined. Check and see if you do have UR13V feeding the ciruits or not, check the buck regulator switching circuit runs by IC9603 (LV5893).

[jkomorek]

Re: LCC5255U going to error standby

Thanks for the post. I will take the readings when I get home and post them. The board clearly stated where the 5v standby and 12v for the inverter boards were supposed to be, and I confirmed that the 5v was fine (I didn't bother with the 12v since a failure signal was cutting power anyway)

What I couldn't figure out was which pin supplied the 3.3v which the initial error message was complaining about.

I just learned about 'the hairdryer test' and will give that a shot as well.

I have attached a photo of the 12 pin connector. Working from the photo, here are the measurements from left to right:

4.99
0
0
0
3.158
0
0
0
0
0
0
0

[budm]

Re: LCC5255U going to error standby

Can I get brighter pictures of the whole top side of the power supply board, and four 1/4 sections of the board as well, same for the bottom side of the board? I need to find out how the 13V is generated.

[retiredcaps]

Re: LCC5255U going to error standby

Can I get brighter pictures of the whole top side of the power supply board, and four 1/4 sections of the board as well, same for the bottom side of the board? I need to find out how the 13V is generated.

Here is where I jump in again and remind posters that what budm is going to do takes a lot of his time to trace out and draw you a schematic. If you are not going to follow through on this repair, say so now so he doesn't waste potentially hours of his time.

The reason for posting this is some posters have given up after regulars have spent many hours helping them.

Continue on...

[jkomorek]

Re: LCC5255U going to error standby

I appreciate Budm's time and am attempting to follow the schematic he provided. However, I am not experienced so please be patient while I figure this out.

[jkomorek]

Re: LCC5255U going to error standby

Ok, I understand now (to a degree) why I initially could not read 13v off of the 12 connector. I had unplugged the connector in order to access the pins which must have cut some sort of signal. While i do not understand more than this at the moment, at least i can now read power out of this connector by forcing the psu on and probing through the top of the connector without disconnecting it.

I will now move onto the main board.

[jkomorek]

Re: LCC5255U going to error standby

I believe that I have verified at 13v is feeding the circuits. I checked the following pins and found almost exactly 13.06v on each one:

IC9601 - pin4
IC9602 - pin 2
IC9603 - pin 2
IC9604 - pin 2
Q9601 - pins 5 & 6


I am still looking into the MAIN5, MAIN6, etc. pins...

[budm]

Re: LCC5255U going to error standby

If you look at the diagram I red lined, you will see the 3.3v output (on the right side of the L9603) at the IC96023, you can measure it across C9625. The circuits need that voltage.
@RC-Thanks!

[jkomorek]

Re: LCC5255U going to error standby

I am having a difficult time finding C9628 or C9629 ( I am assuming that these are very small capacitors not labeled on the PCB); however, I did manage to test the leads for L9603. It appears that one lead measures around 1.990v while the other measures around 1.945v. Sorry, I cannot tell which lead is facing IC9603 at the moment.

Either way, it appears that one of these leads should measure 3.3v according to the schematic. Is this correct?

In case it is helpful, I have uploaded front and back photos of the main board.