Sharp LC-26AD5E Always On once connected

[passete]

Hello guys,
Got here a Sharp LCD with this wierd sympton, once i connect the power plug, the tv turns ON (green led on front, and the relay on psu clicks), but the display stays black and impossible to turn OFF with remote or manually.
I have disconnected a connector (photo above) that goes from psu to the input pcb and now it doesn't turn on once connected.

Can anyone help me please ?
Thanks

[dick_barton]

Re: Sharp LC-26AD5E Always On once connected

Disconnect the other cable lower down and see if the backlights come on when you power on.

[passete]

Re: Sharp LC-26AD5E Always On once connected

Disconnect the other cable lower down and see if the backlights come on when you power on.

Even if the led is Green, there no reaction at all of the tv, and the only way to turn it OFF is by removing the power cable.
Is this problem psu related or is the scaler/input pcb the culprit ?
If you are talking about the connector lower the one i disconnect, there is no change.
thanks

[vinceroger69]

Re: Sharp LC-26AD5E Always On once connected

Maybe a eeprom/spi flash chip issue whats the mainboard number?

[dick_barton]

Re: Sharp LC-26AD5E Always On once connected

What dc voltages do you have or not have at the connectors going to the main board?

[dick_barton]

Re: Sharp LC-26AD5E Always On once connected

Download the manual from

[passete]

Re: Sharp LC-26AD5E Always On once connected

Maybe a eeprom/spi flash chip issue whats the mainboard number?

1817F4140289 (Photo below)

Download the manual from

I can't download the file.

[CapLeaker]

Re: Sharp LC-26AD5E Always On once connected

sure you can... on the bottom of the page... you have to wait a little while,

This file is downloadable free of charge: ...processing...

this will turn to

This file is downloadable free of charge: Get Manual

[vinceroger69]

Re: Sharp LC-26AD5E Always On once connected

main boards are cheap if that is the issue test the psu voltages first though
http://www.ebay.co.uk/sch/i.html?_fr...+111b&_sacat=0

[passete]

Re: Sharp LC-26AD5E Always On once connected

What dc voltages do you have or not have at the connectors going to the main board?

On CP3801 Connector i'm missing the 12 Volts on Pin 8 and 9, the rest is OK.
Instead of 12V i'm Getting 1,59V

sure you can... on the bottom of the page... you have to wait a little while,

This file is downloadable free of charge: ...processing...

this will turn to

This file is downloadable free of charge: Get Manual

You are Right buddy, thanks

[passete]

Re: Sharp LC-26AD5E Always On once connected

From the schematic, the Regulator for the 12V is the Q422, it's 3 Leg Transistor, the reference is KTB1151.
And indeed on the bottom side of the pcb, on this ic location the epoxy is a little burned.
The 100 bucks question, where to find this KTB1151

[vinceroger69]

Re: Sharp LC-26AD5E Always On once connected

maybe something is pulling the 12 volts down? i wonder if you can jump the psu with resistors too test the psu outputs

[passete]

Re: Sharp LC-26AD5E Always On once connected

maybe something is pulling the 12 volts down? i wonder if you can jump the psu with resistors too test the psu outputs

Or maybe i should measure with the connector disconnected from the main board ?
No, it won't work, cause the psu will not turn on .... shutt

[passete]

Re: Sharp LC-26AD5E Always On once connected

The 12V Lines are linked with many reg's on the mainboard, this is gonna be a pain in the mikta ...

[passete]

Re: Sharp LC-26AD5E Always On once connected

I have replaced Q422 and non Change, i still have 1,58V instead of 12V.
I also removed IC3801 and Q3802 but still no change.
Can anyone give a tip ?

[budm]

Re: Sharp LC-26AD5E Always On once connected

I would check the resistance between GND and PIN 8/9 first, then take the reading between GND and output of the Regulator IC3801, Q3804/3805, 3202 output side.
Q3802: do you mean Q3202?
Report the readings.
BTW, what DCV do you have at the BASE of Q422 and GND?

[budm]

Re: Sharp LC-26AD5E Always On once connected

BTW, if something is loading down that Regulator circuit that bad I would expect the fuse F404 1.6A to blow first.