LT-42EM59 sound no picture no flickering blue light

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

Do not worry about the sound yet, lets get the backlights to come on first, so check that 24VDC.

[triplefour]

Re: LT-42EM59 sound no picture no flickering blue light

NES!? excellent choice my friend

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

OK.. back!!! ... HAS sound.. ... checking the backlight inverter voltage both pin 1 on the master and slave with the black prong in the chassis. *testing the power board side extra info* .090 -_- sits there then jumps up to maybe 10v or so for a quick second and back down to .090 when i turn the tv off it goes all the way down to 0v turn tv on hears click. jumps randomly sometimes saying O.L. then sits at .090v

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

What is the DC scale set to on the meter? OL means the voltage went too high to display the value.
In standby there will be not 24V, when power switched is activated the PS_ON from the main board will be sent to the power supply board to turn on the PFC, the 12V/24V power supply, 12V is for sound, 24V is for the inverter. Since you have sound then the 12V/24V must be working which does not match the 24V that you are saying is going up and down, the 12V is generated by the same transformer as the 24V, so the 12V should be going up and down as well, it sounds like measurement problems.

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

http://www.amazon.com/INNOVA-3320-Au...ova+multimeter that's the multimeter i have

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

It is set to DCV, right?

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

umm.... slaps face.......-_- *out of practice noob feeling* all 24v across both the master and slave boards.. thanks for reminding me idk what i was thinking. guess the failing youtube videos where getting to me

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

OK, more likely to have blown F1 fuse with '15' printed on top on the master inverter board. Set the meter Ohm mode, the reading should be about the same reading as when you touch the two probes together.

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

for the f1 fuse. resistance is reading is 0.00 and voltage passing thru it is 23.1

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

OK, then we need to find out we the inverter is getting the BL_ON (ON/OFF) signal from the main board or not, so check the DC Voltage on the last pin (there is a round test pad) on the right of the connector, it should have >2.5VDC on it.

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

3.39 at the pin

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

OK, so it does have 24V, bl_on.
Did you ever see the backlights flash on for seconds at all?

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

No it doesn't come on for a second at all i just sat in front of it and watched it .. sound cuts on from the nes and no backlight flash or screen showing at all *checked with flashlight*

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

BTW, you did check all the fuses of both inverter boards beside the black one, right?
I also need the STATUS, E-PWM, and I-PWM DC voltage readings.

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

no ran out of time i'll go do that here in a minute. They should all read 0 on ohms right?

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

Yes.

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

ok. all the fuses near the caps that are labeled with a 3 all read from .2 up to .5 ohms

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

Ok I-pwm was 2.62v E-pwm ranges from .346v. .5v, and Status hovers from .180v to .210v also looking at the schem for the power board i noticed the signal board is connected and deals with part of the BL_ON and the lcd power. could the signal board be the cause to why the backlights and lcd arn't coming on?. *note* i'm still happy to do the voltage readings for ya to make sure*

[budm]

Re: LT-42EM59 sound no picture no flickering blue light

So far all the required signals for the inverter are present. Hmm.
The signals for the inverter board are routed through the power supply board, the power supply board is used for junction point for clean wiring.

[jdoncouse]

Re: LT-42EM59 sound no picture no flickering blue light

Ok here's something i thought of. I see the multiple test points near where the inverter plugs into the lcd for the backlight. What should those voltages be? I wish i had a schem for these inverters lol it'd be so much easier on me.