grundig vlc4120 c .. does not turn on ..

[Hjolli.hardar]

Grundig also known as beko and seems to have a lot of LG boards.

here is the service manual https://www.scribd.com/doc/111572913...BS-8041S-8042S

powersupply type fsp337-3f01

ok i get only 5 volt's when nothing is connected to the power supply.
when i connect i get
5v
12v
24v
dim 3.3v
standby 1.1v
bl 0.014v
and starnsformer purring.

when plugged in my blue light starts dim the brightens up like it's being turned on. but buttons don't do anything.

no back light no sound.

i found a diode on the primary part when i put my multi on it the purring lowers but the volt are jumping up and down.

i'm thinking i need to fix the standby voltage but i'm a bit lost as to where the problem might be ..checked the caps the all seem to be ok. in board and off. diodes seem to be fine.
well every thing i know seems to be fine besides the funky volts on stby and bl .. therefore me lost ..

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

well i kept on going through board and and ripped out all the regulators and transistors ..basicly all the 3 legged buggers .. tested them every one ok.
i'm starting to think it's something on the bottom side of the board.

[reaper57]

Re: grundig vlc4120 c .. does not turn on ..

Is the standby volgate ok when the power supply cable is unpluged from the main board?

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

nope .. only get 5 volts to 5 voltplug.. and I've been watching the light better and it seem to be dim at plugin then brighten and dim again .. blue diode.
but of course only when main board is connected .. only diff i see when pushing on of button is a jump in main(big) cap about 1 volt.
It looks like dirty electricity it's not stable in the power supply .. out of the diode d105 i mentioned i'm seeing jumps from 1v to 180v and the main strans former purr changes.
also when i put my metter on q102 and q101 .. mid leg ..

i still havn't pulled out cooling grill with th201 and acompanying d201cq045 and d202-205 which are 3 legged can't realy read on the because of caps in the way .. but seems to be stp30h100ct

[Agent24]

Re: grundig vlc4120 c .. does not turn on ..

Please post photos of the board, show components you are testing, hard to follow without seeing.

If you can download that manual and upload it here or elsewhere, that would help, I can't view it all online as I don't have an account on that site.

[budm]

Re: grundig vlc4120 c .. does not turn on ..

"ok i get only 5 volt's when nothing is connected to the power supply.
when i connect i get
5v
12v
24v
dim 3.3v
standby 1.1v
bl 0.014v
and starnsformer purring."

If the standby power supply is not working you will not be getting the 12V or 25V which is turned on by the main board which runs on the standby 5V.
The inverter board is not getting the BL_ON signal from the main board, it is getting only 0.014V.
BTW, what do you use for the Ground ref for the meter when you are checking the voltages in the primary side of the circuit. What DC voltage do you get at the two legs of the main filter cap in the primary side when the TV is off and when the TV power switch is activated?

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

volts on main cap 394v use metal frame as ground ..
i just replaced grill with q601-2 and d 602 -fb601..
backlight comes on now ..
get bl Q 1.777v others are the same .
purring stopped .. but i get nothing on the screen ..

[budm]

Re: grundig vlc4120 c .. does not turn on ..

OK, when you make any DC voltage measurement in the primary side of the circuit, you will use the negative leg of the main filter cap in the primary side as the ground ref for your meter, you cannot use the metal frame, that is why the voltage readings do not look right. When you work on the secondary (cold side), you can use the metal chassis as the ground ref for the meter.
You are not getting the backlights because you do not have BL_ON signal.

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

got backlight on now 1.770v .. purring almost disapeared .. but i get no pic.

the measures i was posting come from the cold side.
i just hit the hot side diode by accident and noticed the purr change.
but it seems the problem lies in these q's i just put back in .. nothing else has been done though the window is open and it's blowing a bit cold straight down on the tv ..

gonna try connecting some sound to a source and see what happens

[budm]

Re: grundig vlc4120 c .. does not turn on ..

OK, so the backlights are on but no pictures, then verify that the LVDS cable between the main board and the T-CON board is properly connected, if it is, then the next thing will be checking the DC Voltage at both ends of the SMD fuse on the T-CON board.

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

T-con fuse gives me 0v, 0.2 ohm .. so i gues no power is heading there ..

the main board is VEV190R-4 v-0.. seems to be LG manufactured though it comes up in searches as Beko, Grundig or Lg like all the boards on this one ..

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

time to put kids to bed ... getting around 1mv on the fuse .. will take a closer look at the main board and t-con to morrow

[budm]

Re: grundig vlc4120 c .. does not turn on ..

OK, it means that the main board is not supplying the Voltage to the T-CON, it is usually done through a switched MOSFET on the main board that is turned on when the power switch is activated.

[ERICSSON89]

Re: grundig vlc4120 c .. does not turn on ..

please can u upload pictures of the psu board, main board and TCON board? both front and back please

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

will do ..

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

pics

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

when i woke up i was going to continue but now there is no purring .. no dim, 12v or 24v
all i get now is 5v, 1.5v on bL and stby 1.1v

and nothing was done since last nite .. BL worked and now it don't .

[Agent24]

Re: grundig vlc4120 c .. does not turn on ..

Have you inspected all the solder joints? Maybe intermittent connection somewhere.

[Hjolli.hardar]

Re: grundig vlc4120 c .. does not turn on ..

gonna rip it a part tomorrow and see what i find

[vouager]

Re: grundig vlc4120 c .. does not turn on ..

You have Brocken Firmware!!!!
Ask here for Help:
http://forum.iwenzo.de/reparatur-von...amer--f26.html

Sorry for my bad English