58l1350uc no power/lights

[tmlfan]

so i was given a toshiba 58l1350uc tv that doesn't work, when i plug it in there is no lights or anything on the front panel, i have been following the other thread located here https://www.badcaps.net/forum/showth...403#post615403


i have taken the back off of the tv and started to take measurements, plugged in i get 5v output off of the main board but not 12v

pwon = 3v

power mosfets c101a/c101b = 360V on both

i don't see any leaking/bulging capacitors but havent taken any of them out to test yet and the fuse thats in the main power board tested good also

[dskall]

Re: 58l1350uc no power/lights

Are c101a/c101b your main caps= 360V on both. You don't list a country. What voltage are you?

[tmlfan]

Re: 58l1350uc no power/lights

sorry yes, c101a and c101b are the main caps and i am getting 360vdc on bith which is what i am suposed to and i am located in canada

[dskall]

Re: 58l1350uc no power/lights

360v seems low. Think you should be getting 390v

[dskall]

Re: 58l1350uc no power/lights

Need good clear straight on pictures of back of tv with cover off and each board.

[dick_barton]

Re: 58l1350uc no power/lights

As Dskall says that voltage is to low and is given as 390V in the thread you refer to.

[dick_barton]

Re: 58l1350uc no power/lights

With your meter set to DC volts what voltage do you have when you connect the black probe to Pin5 and red probe to Pin3 of U801.
Do not let the probes slip.

Edit
Some good photo's of your power supply board would be useful.

[Andrew F. Ali]

Re: 58l1350uc no power/lights

with your meter set to dc volts what voltage do you have when you connect the black probe to pin5 and red probe to pin3 of u801.
Do not let the probes slip.

Edit
some good photo's of your power supply board would be useful.

+10

[tmlfan]

Re: 58l1350uc no power/lights

Let me know if these are good enough

[tmlfan]

Re: 58l1350uc no power/lights

black probe to pin 5 and red pin to probe 3 i get -17.5 volts

also getting 153 Vdc across power transistor BD1 when plugged in

with main board unplugged i get 170Vdc across power transistor/170Vdc across c101a and c101b and -15.8 on pin 3/5 of u801

[tmlfan]

Re: 58l1350uc no power/lights

another thing to note is when i take Vdc readings across pins 1/2/3 from this pic here from previous thread on my board i get voltage readings of 0/0/16.5 but that is with power board only plugged into wall and no other boards, dont know if that matters or not...pic is from previous thread

[dskall]

Re: 58l1350uc no power/lights

170v in standby is good 350v is low but pfc is working. I would check feedback resistors on boost controller for low resistance. Others correct me if i'm wrong

[dick_barton]

Re: 58l1350uc no power/lights

Ooops sorry but I got the probe connections the wrong way round in the photo so just need to reverse the voltage reading to +15.8V

The STR-A6069H has a maximum operating voltage of 16.8V so the voltage seems to be correct as per post #10

It looks as though the PFC circuit is working (360V) but it's not bringing the supply voltage across those capacitors C1A/C1B fully up to 390V.

With the set powered off and unplugged from the wall socket I would check the resistance of R801, R802, R803, R808 & R701 and ensure they match what their supposed value.

[dskall]

Re: 58l1350uc no power/lights

Is u801 for standby or pfc control

[tmlfan]

Re: 58l1350uc no power/lights

r801 = 1.31M ohms
r802 =2.17M ohms
r803 =145 ohms
r808 =4.87k ohms
r701 =1.00M ohms

if i read resistors right then this is what values are supposed to be

r801 = 2.2M
r802 = 2.2M
r803 = cant really make it out, looks like 274 wrote on it with a line under the 4
r808 = 2.2M
r701 = 1.0M

[dskall]

Re: 58l1350uc no power/lights

You can replace bad with 1/4w regular resistors

[tmlfan]

Re: 58l1350uc no power/lights

any idea about r803

[dick_barton]

Re: 58l1350uc no power/lights

My thoughts here are that when reading other threads where the PFC voltage was not quite up to what it should be, it often came down to the fact that one or more of the resistors in the resistor chain was out of tolerance. Replacing them brought the supply back to it's normal working value.

In the attached photo it would be the resistor chain feeding the BR pin of the IC

[tmlfan]

Re: 58l1350uc no power/lights

i changed r801/r808, no change in voltages, any idea what value r803 should be, its smaller than the rest and like i said it looks like it has 274 wrote on it with a line under the 4 and is only reading 4.87k ohms....unless it is supposed to be 472 which would make it 4700 which would make sense

[dick_barton]

Re: 58l1350uc no power/lights

There is a capacitor C808 in parallel with R803 that I would check. The problem is without a schematic I don't know what the value should be.