westinghouse LVM-47w1

[smai]

so here is what i got and have done

Monitor powers on, backlight lights up and input choice (DVI1) appears
5-10 seconds later i hear a buzz and the backlights power off audio i think is still on (not sure if there is a video )

i have removed the covers all caps seem okay and nothing blaring obvious

with the power on on the power board pins marked with 24 volts have 24 volts, pins marked with 12v have 11.8v

with the power on, the inverter boards (24 volt boards) there are 24v coming in (5 wires) even after the lights turn off

the only thing i have found so far (on justanswer) is a wire, from the main board to the inverter board, labeled BL_ON should show 24V at power up and hold, it only shows 3.3V

say i jump a pin to supply 24v to the BL_ON from the pin next to it, to test the above statement, would that be safe ?

so now i can decide what is causing what, are the inverter board shorting out ? is the main board bad for not showing 24V? or is the 11.8 V coming out of the PS board not enough ? is that buzzing noise a bad component onthe PS board ?

any help is much appreciated

[smai]

Re: westinghouse LVM-47w1

okay i added pics of the PSB

when the TV is off the large thing in the middle makes a whiny noise when the tv is powered on it stops

when the backlight powers off the small grey box (circled) makes a scratching noise or its in that area

any idea on what these parts are? and if that is the cause of my problems or the reaction from the problem

thanks

[multimeter]

Re: westinghouse LVM-47w1

that 3.3v sounds like standby power,to turn the inverter on...

post up a pic of the power supply connectors and mainboard ones,showing the legends next to there connector

will need to be good quality pic and close,

[smai]

Re: westinghouse LVM-47w1

to clarify a bit BL_ON show 0 volts when off, then shows 3.3v when the power button is pressed and stays 3.3volts even after the backlight turns off

the 24volts i think its suppose to show at power on (information from justanswer) could be for a different mainboard inverter board combo

i have had no luck sourcing a service manual, i talked to westinghouse and they say there is no service manual for the boards but they think the inverter boards are bad

[multimeter]

Re: westinghouse LVM-47w1

to clarify a bit BL_ON show 0 volts when off, then shows 3.3v when the power button is pressed and stays 3.3volts even after the backlight turns off

the 24volts i think its suppose to show at power on (information from justanswer) could be for a different mainboard inverter board combo

i have had no luck sourcing a service manual, i talked to westinghouse and they say there is no service manual for the boards but they think the inverter boards are bad

main board is working then,bl_on will show 0v when in standby,power on,the bl_on will go high at 3.3v,so thats all good.your 12v will be for mainboard,the 24v for the inverter.

can you put some good pics up of the inverter?,those last pics were excellent.and can go from there then.

when the inverter shuts down ,do you see a faint image when you shine a strong flashlight at the screen,bringing up the menu will make it easier to see.

[smai]

Re: westinghouse LVM-47w1

i have all the boards off at the moment but i do believe there was audio, here are some pics not quite as good ill try and get better ones

[smai]

Re: westinghouse LVM-47w1

2nd try at uploading

[multimeter]

Re: westinghouse LVM-47w1

need to check,primarys and secondrys on all those transformers

multimeter set to kohm or autorange if it has it

the secondarys are opposite the ccfl tube sockets,there are little round copper pads next to the sockets,measure from these

primarys opposite end

when you return results here,write it something like this

transformer#1 secondry 1500kohm - primary 0.5 ohm

transformer#2 blah blah and so on

[smai]

Re: westinghouse LVM-47w1

so in this picture blue to black is primary and red to yellow is secondary ?

[tom66]

Re: westinghouse LVM-47w1

Not sure about primary, but secondary is correct. Secondary is most important for now.

[multimeter]

Re: westinghouse LVM-47w1

red and black,on the same transformer is primary

blue and yellow,on the same transformer is secondary

the primary side rarely fails

[smai]

Re: westinghouse LVM-47w1

okay so far yellow to blue secondary with my ohm meter set to 200K

master board
1 3.7
2 3.6
3 168.2
4 3.6
5 3.7
6 164.6
7 3.6
8 3.6
9 168.7
10 3.7
11 3.7
12 165.8

slave board
1 3.7
2 3.6
3 166.5
4 3.7
5 3.7
6 162.4
7 3.7
8 3.7
9 163.5
10 3.7
11 3.7
12 163.1

tom66 yellow to red all read 1.8

[tom66]

Re: westinghouse LVM-47w1

Yellow to blue? Or yellow to red?

[multimeter]

Re: westinghouse LVM-47w1

hmmm,how many sockets for ccfl's are there and how many transformers?,ive noticed it looks like there are 2 transformers to one ccfl socket,didnt spot that!

24 transformers and 12 ccfl sockets?

[smai]

Re: westinghouse LVM-47w1

Yellow to blue? Or yellow to red?

two different opinions so i checked both, so i did yellow to red they all read 1.8

hmmm,how many sockets for ccfl's are there and how many transformers?,ive noticed it looks like there are 2 transformers to one ccfl socket,didnt spot that!

24 transformers and 12 ccfl sockets?

yes 24 transformers and 12 sockets per board

[tom66]

Re: westinghouse LVM-47w1

Yellow-red might be secondary, they look good if so. Not certain though.

[smai]

Re: westinghouse LVM-47w1

thanks for the replies so far you guys have been helpful

any other thoughts?

so the information so far

powers on, signal sent and holds, backlight goes off, 24V remains at the plug, there is a noise after the backlight powers off on PCB from what looks like a square capacitor HJC .47uf (i think its a safety cap?), TV remains on, ONLY when the TV is off (standby) there is a faint whining or squealing from the main transformer on the PCB

which do you think is most likely PCB, inverters or main board? or can the bulbs be bad?

[multimeter]

Re: westinghouse LVM-47w1

can you pop up a pic of this cap? and the part number printed on it,ive never known them to fizz like that before,also can you pop up a pic of the solder side where this cap is?and circle/highlight where its solder points are,im really hoping this isnt a ccfl tube failiure,how long does the screen light up for before it shuts down?those ohm readings from the test results you did,seem quite uniform,and some do come out at around 1.8kohm,i was tired last night

we will get there dont worry

[smai]

Re: westinghouse LVM-47w1

it stays lit probably about 3-5 seconds, im 90% sure its this cap that is buzzing (almost sounds like a cricket) right after the lights go out, when i disconnect the inverters from the power board and power on it doesnt make that noise, so with my logic either the boards are causing it to make the noise or the noise is causing the boards to turn off

[multimeter]

Re: westinghouse LVM-47w1

there could be a a boarder line resistance short happening ,can you do a resistance test to ground on the +rails on the inverters?,you should see lots of of kohms,if there is a few ohms,that could indicate a short somewhere,and will have to check the transformer drivers for shorts,passives etc

a short would filter back through the feedback circuits ,and cause some reverse voltage,and that may be the sound your hearing from that capacitor under more load,and the mainboard shuts the psu down and so on