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Equipment Repairs => LCD TV forum => Topic started by: handsomejackuk on March 04, 2011,14:54:41

Title: stuck on standby vestel 17pw20
Post by: handsomejackuk on March 04, 2011,14:54:41

Hi to all....

newbie here.....

have Red make TV from sainsburys.. has samsung lta320aa05  32 inch panel... vestel 17pw20 power supply... vestel 17mb12-3 mainboard... samsung SSi320a12 invertor board....

power light comes on, and remote will turn tv on sound is working, but no backilght...

have checked power to invertor board and is present.... 24v healthy...

there are two other power terminals on invertor board one is dimming control which is healthy.. the other which is panel on off is very low at 0.8v...

Does anyone think this could be the power supply... ??

where to check voltages on power supply what should they be ?

dont want to replace invertor board if its not faulty

please Advise

Title: Re: stuck on standby vestel 17pw20
Post by: sparky on March 04, 2011,15:32:16

hi
fault prob on inverter pcb smf o/c or one one of transformer
if you ok with meter check the transformers,or swap
 inverter pcb
dave

Title: Re: stuck on standby vestel 17pw20
Post by: handsomejackuk on March 04, 2011,15:45:50

Sparky,,,,

can you elaborate on what SMF o/c is ?

i can test the transformers no prob....

I just wondered why there was no 5v to the invertor board, as there supposed to be to light up the ccfl's

Please advise....

5.2. Inverter Input Pin Configuration

1 24 V
2 24 V
3 24 V
4 24 V
5 24 V
6 GND
7 GND
8 GND
9 GND
10 GND
11 No Connection (DO NOT CONNECT)
12 Backlight On /Off [ON:2.4 – 5.25 V, OFF: 0 - 0.8 V]
13 Dimming Control [0V:Min, 3.3V:Max]
14 No Connection (DO NOT CONNECT)

pin 12 has 0.88v or lower...

http://www.uktvparts.co.uk/ssi320a12-p-165.html?currency=EUR

(http://marcoselectronics.com/images/SSI320A12.JPG)


(http://winner.od.ua/myfiles/Structure_LCD/HANSEATIC%20LC32-250S/INV.jpg)


THanks    Al..

Title: Re: stuck on standby vestel 17pw20
Post by: watteau on March 05, 2011,02:46:09

Hello,

It's possible the power-supply is causing the problem, substitute if you can, otherwise check the diode D861, transistor Q841, and capacitor C904 between pin 12, on PL802, and pin 1 of PL803, on the power supply, also check any fuses on the inverter PCB for o/c.  Otherwise it's a good chance the inverter is at fault (transformers are worth a check, compare the resistance readings, various transformers are available from CHS).

Good Luck,
John

Title: Re: stuck on standby vestel 17pw20
Post by: sparky on March 05, 2011,03:51:37

hi
smf= surface mounted fuse,on inverter panel look were the
24v rail comes in might say f1 etc
dave

Title: Re: stuck on standby vestel 17pw20
Post by: handsomejackuk on March 05, 2011,06:08:40

Dave,

thanks for that very helpful will try what you suggest did not know about surface mount fuse... Will investigate...

great real helpful....

Thanks Al.....

Title: Re: stuck on standby vestel 17pw20
Post by: handsomejackuk on March 06, 2011,08:29:06

Hi...

Smf tests ok... what i dont have is one of the signals on the connector on the invertor board....  Ihave 24v and ground, I have dimming control, but no back light on signal... is it safe for me to put 5v on to this pin to see if it lights up the tubes...

just want to prove this board works...

Transformer outputs appear ok...when tested with a meter on resistance...

Title: Re: stuck on standby vestel 17pw20
Post by: sparky on March 06, 2011,08:47:05

hi
just try need inverter panel
dave

Title: Re: stuck on standby vestel 17pw20
Post by: watteau on March 08, 2011,03:32:28

Hello,

You try can supplying about 5v to the 'on' pin, but make sure you disconnect the pin 12 lead going into the inverter plug before applying it. If it comes on, and you have checked the components listed on the power-supply (as these can drag down this switching voltage), the switching voltage from the main pcb could be the cause.

Regards,
John.