Bush LCD32TV022HD sound backlight no picture

[notallbad]

PS bd 17PW15-8
Logic bd 17MB15E-5
Inverter bd KLS-S320BCI-M Rev:01
T-Con bd 320WSC4LV5.6
Panel Samsung LTA320WS-L03

TV powers up on stby (red led power light), press the 'power' keypad button and TV turns on (green led power light), though this I have read can be misleading.
Backlight comes on but no picture, menu does not display either, pressing keypad buttons seems to make the 'display' alter the brightness/flickers but no image appears on the screen.
Sound is present when connected to a source.

On initial inspection their were a couple of bulging/leaking caps on the PS bd which I have replaced but symptoms the same. Caps C806, C851, C863 1000uF 16v and C857 4700uF 6.3v.

Main filter cap reads steady 320v in stby and 381v when 'on'.

In stby:
PL803 Pin 6 (Stby) 2.97v
PL806 Pins 1 & 2 (5v stby) 4.85v, Pins 3 & 4 (3.3v stby) 3.2v

TV 'On':
PL801 Pins 1-5 (24v) 23v
PL802 Pins 1-5 (24v) 23v, Pin 11 (A_Dim) 2v, Pin 12 (BL On/Off) 3v
PL803 Pin 1 (BL On_Off) 3.1v, Pin 2 (A_Dim) 2v, Pin 6 (Stby) 0v, Pin 7 (33v) 33v, Pin 8 (12v) 11.6v
PL805 Pins1 & 2 (5v) 4.75v, Pins 3-7 (VCC 3.3v) 3.21v
PL806 Pins 1 & 2 (5v stby) 4.85v, Pins 3 & 4 (3.3v stby) 3.2v

Shall add photos of boards shortly.

Is it most likely a faulty T-Con bd? Don't seem to be able to locate a fuse on there!
Readings with T-Con disconnected from the Display Panel, not sure how to have it connected to the panel and have access to get DMM readings.
VOn reads 0.4v
VIn reads 0.7v
VR 0.315v
VDD_2.5 reads 0.7v
Not really sure what else to check on there but would think Vin and Von should be higher as should VDD_2.5.
There are 4.7v and 3.2v on the connector from the Logic bd to the T-Con as well as some signal volts reading about 1.17v.

[Andrew F. Ali]

Re: Bush LCD32TV022HD sound backlight no picture

Look at the T-CON Bd...There is a fuse that should have 12Vdc on both sides.

[notallbad]

Re: Bush LCD32TV022HD sound backlight no picture

Thanks but can't locate the fuse. If there is, I can't see it.
None of the components are labelled 'F' as you would expect.

[notallbad]

Re: Bush LCD32TV022HD sound backlight no picture

Could possibly be CP101 and CP102, Circuit Protection?
One reads SC (CP102), the other OC (CP101).

This would suggest Logic bd fault as theres definately no 12v on the logic bd connector to the tcon.

Pins 26-30 on T-Con bd and Pins 9, 11, 27 and 29 at Logic bd end. Reading 4.74v.

Is this T-Con run from 5v or 12v?

[diif]

Re: Bush LCD32TV022HD sound backlight no picture

Could possibly be CP101 and CP102, Circuit Protection?
One reads SC (CP102), the other OC (CP101).

This would suggest Logic bd fault as theres definately no 12v on the logic bd connector to the tcon.

That's what I was thinking they look to have a P on them. That's a 3A fuse.

[budm]

Re: Bush LCD32TV022HD sound backlight no picture

One is under the glue by the LVDS connector, CP101, the second one is CP102 is just above CP101.
CP = Circuit Protection

[notallbad]

Re: Bush LCD32TV022HD sound backlight no picture

That's what I was thinking they look to have a P on them. That's a 3A fuse.

Thanks, was just about to ask what the fuse rating is. Yes, 'P' printed on it, just to confirm.

I don't want to simply jumper between the pins as its possible/likely a fault condition caused it to blow in the first place, but then again, its busted anyway! Though possible its only the fuse. Hopefully its not a bad panel that caused it.

[notallbad]

Re: Bush LCD32TV022HD sound backlight no picture

One is under the glue by the LVDS connector, CP101, the second one is CP102 is just above CP101.
CP = Circuit Protection

Thanks budm, yeah spotted them and glue didn't help. Under the glue its printed on the board 'IN'. Guessing input.

[notallbad]

Re: Bush LCD32TV022HD sound backlight no picture

Ok, temporarily jumpered across in place of the blown fuse CP101 and the TV powers up and picture back (HDMI source input) and working as it should, for now.

Thanks ALL! So now to find a suitably sized 3A fuse and replace more caps on that PS.