42" Magnavox trouble

[Larry1988]

Hello guys this will be my first post so plz be gentle lol. im working on amagnavox 42mf439b/f7 the issue is it powers on i get a solid green light and then the standby light flashs once every 15 to 30 secs ive tryed checking the screen with a flashlight as no backlighting comes on but no dice. ive checked all the caps and to the eye no bulging or bad caps. the set is unresponsive to the power button will only shut down if i ulplug the main board or the cba board. ive replaced the digital main board just out the go since it was pretty cheap. next thoughts were t con or inverter board ? im somewhat dmm friendly and can solder so fire away any help appreciated!

[nomoresonys]

Re: 42" Magnavox trouble

maybe check the fuse on the tcon board, the label will start with an F for fuse.

[nomoresonys]

Re: 42" Magnavox trouble

careful when working with the power supply board, HIGH VOLTAGE on primary side.

[Larry1988]

Re: 42" Magnavox trouble

what would be the voltage for it i found one i think im not at the set currently but i got 24volts on both side if i remember correctly

[budm]

Re: 42" Magnavox trouble

Well, start with this so we can see what we are dealing with.
https://www.badcaps.net/forum/showthread.php?t=39740

Also read this:
Basic LCD TV and Monitor troubleshooting guides.
The link is under my signature.

[Larry1988]

Re: 42" Magnavox trouble

i do apologize for any blurry pics im taking them and have to get to a location to upload as internet at home is slower than 56k lol any blurry pics i will retake and try again and theres a few i left out i need to retake as well

[Larry1988]

Re: 42" Magnavox trouble

a few extras

[Larry1988]

Re: 42" Magnavox trouble

thanks for taking the time budm and nomoresonys im very new to this have one repair tv wise under my belt but really enjoy working on electronics and learning from those who have more experience than me. most of my electronic back ground other than tvs is just building my own pc's.

[Larry1988]

Re: 42" Magnavox trouble

i quick i know probably newb question but on the inverter board where it is labeled high voltage it has a small copper like space..is this a testing point for voltage ?

[Larry1988]

Re: 42" Magnavox trouble

loved the pdf's for lcd repair budm

[ibgm]

Re: 42" Magnavox trouble

On pic 121643 we can see 2 fuses in the inverter board, 8A/160V. I would check those first. Good luck!
They are near the connectors.

[budm]

Re: 42" Magnavox trouble

So you replaced the big brown board on the right?
This one of those FUNAI/SYLVANIA/EMERSON/PHILIPS/MAGANAVOX TV.
Is there a chassis number printed on the model number sticker?
For example:
42MF438BF7_LC8.14LA
"LC8.14LA" is the chassis number.

[Larry1988]

Re: 42" Magnavox trouble

Yes both fuses on inverter board Check out at 24v and I get voltage at the caps on the inverter board but past the caps those transformer things lol dunno what there called there is no voltage. Both sets of connectors the red wires are all 24v.

[Larry1988]

Re: 42" Magnavox trouble

ok so budm this is the board that i replaced the digital main and then the sec picture is of the other connector on the inverter. all the red wires as i said read out 24v but the 4 blue wires voltage are all very low im not near the set to take the readings again but i will tonight .... and i will also try and get that model number you were asking for.

[Larry1988]

Re: 42" Magnavox trouble

ok budm the only thing i see on the model number sticker other than 42mf439b/f7 is is off to the side in a white box that says S fl9.2

[nomoresonys]

Re: 42" Magnavox trouble

what would be the voltage for it i found one i think im not at the set currently but i got 24volts on both side if i remember correctly

I check fuses in diode mode, one probe on each end, if no reaction or stays ol, then its probably bad, if reading is close to 000 then its prob. good.

[nomoresonys]

Re: 42" Magnavox trouble

maybe check expected voltages coming from power supply, a lot of them have legends by the connectors, that show expected voltages 3.3 ,5 ,12 ,24, etc.

[Larry1988]

Re: 42" Magnavox trouble

ok on this inverter board i get 24v across the red wires the vbl then the rest as follows

status 0v
E-pwm 0.7
I-pwm 0v
On/off 1.7v

and sony i will have to try testing those in diode and let you know what i get

[Larry1988]

Re: 42" Magnavox trouble

fuses on inverter board read out 000

[Larry1988]

Re: 42" Magnavox trouble

Found this on my search of the internet thought i would share it !!