vizio

[markmac3]

Re: vizio

Right now Op has no PS-ON so there will be no 12V to test.

12vdc testing: disconnect the 12vdc TV load from the power supply board and attach one #1157 (using
just the Hi filament), the 12vdc output should stay at 12v (+/-1v), if not, the power supply has regulation
problem.

i unplugged the t-con board from main board, hooked up the 1157 bulb to 12v pin next to ps_on. pushed power button , no light. is this right?

[markmac3]

Re: vizio

I just tried this. I found one of the voltage reg that had 3.3v and jumped it to the ps_on. light came on, had 12v.

[budm]

Re: vizio

As I indicated, your main board is not sending the PS-ON to turn on the power supply, so you need to find out why it is not sending the PC-ON. You can start by testing all 3 legs of all the Voltage regulator on the main board.
BTW, jumping the PS-ON directly to the power source with out using current limiter resistor is not good idea, especially if you did remove the PS-ON wire going back to the main board first which you can damage the switched Transistor that controls the PS-ON signal line.
You should also use low beam of the 1157 so you will reduce the inrush current, if you check the cold resistance of the 1157 filaments, you will find that it has very low cold resistance that can easily overload the power supply or damage it. You can easily calculate what the inrush current will be using Ohms law.

[markmac3]

Re: vizio

As I indicated, your main board is not sending the PS-ON to turn on the power supply, so you need to find out why it is not sending the PC-ON. You can start by testing all 3 legs of all the Voltage regulator on the main board.
BTW, jumping the PS-ON directly to the power source with out using current limiter resistor is not good idea, especially if you did remove the PS-ON wire going back to the main board first which you can damage the switched Transistor that controls the PS-ON signal line.
You should also use low beam of the 1157 so you will reduce the inrush current, if you check the cold resistance of the 1157 filaments, you will find that it has very low cold resistance that can easily overload the power supply or damage it. You can easily calculate what the inrush current will be using Ohms law.

this was all the voltage regulators I saw on main board and there readings
u11 no voltage on any leg
u9 in 4.9 out 2.5 gr 1.2
u8 in 2.5 out 1.2 adj 0
u2 in 4.9 out 3.3 gr 2.0
u5 in 4.9 out 2.6 gr 1.3
and the ps_on wire was still on when I tried the jump.

[markmac3]

Re: vizio

As I indicated, your main board is not sending the PS-ON to turn on the power supply, so you need to find out why it is not sending the PC-ON. You can start by testing all 3 legs of all the Voltage regulator on the main board.
BTW, jumping the PS-ON directly to the power source with out using current limiter resistor is not good idea, especially if you did remove the PS-ON wire going back to the main board first which you can damage the switched Transistor that controls the PS-ON signal line.
You should also use low beam of the 1157 so you will reduce the inrush current, if you check the cold resistance of the 1157 filaments, you will find that it has very low cold resistance that can easily overload the power supply or damage it. You can easily calculate what the inrush current will be using Ohms law.

I found a total of 7 voltage regulators on main board. 6 had the 1.25v between adjust pin and center pin and the correct voltages on the output (+1.25v). the one that did not read any voltage is different(bigger) than the others. theres 5- 1117, 1- 7805 and 1- 1084. the 7805 did not read any voltage on any pins. the other day when I jumped the ps_on,(and have not done that again) I did have voltage on that regulator, 12v in 4.9 out is what I remember. what would be my next step?

[markmac3]

Re: vizio

I saw the post from retiredcaps on how to display my readings from voltage regulators. I hope this is correct. all look good except U11. is it bad? also cant find datasheet for U9, I cant get a clear picture to show but the only other markings a what looks like a backwards C with 2 dashed lines vertically through the C and 2 vertical dashed lines to the right of the C.

U11
7805CT
AMK 805G
pin 1= 0v
pin 2= 0v
pin 3= .270

U4
AMC1117
F0838G
pin1 = 2.076
pin2 = 3.336
pin3 = 4.960

U9
1084
0810EL
pin 1 = 1.256
pin 2 = 2.508
pin 3 = 4.917

U8
AMC1117
F0838G
pin 1 = 0
pin 2 = 1.261
pin 3 = 2.508

U2
AMC1117
F0838G
pin 1 = 2.050
pin 2 = 3.307
pin 3 = 4.916

U5
AMC1117
F0838G
pin 1 = 1.383
pin 2 = 2.647
pin 3 = 4.905

U7
AMC1117
F0838G
pin 1 = 2.082
pin 2 = 3.341
pin 3 = 4.919

[attainteddragon]

Re: vizio

your vr's are good. you can not consider u11 bad as it does not receive any voltage.

[markmac3]

Re: vizio

your vr's are good. you can not consider u11 bad as it does not receive any voltage.

What would be my next step, kinda stuck on what to check.

[budm]

Re: vizio

So right now we are dealing with the original boards. What do you get as far as the Voltages and the PS-ON if you install the replacement main board you bought?
BTW on post #17, you indicate of having 3.3V at the power switch, but does it change state when the power switch is activated?

[markmac3]

Re: vizio

So right now we are dealing with the original boards. What do you get as far as the Voltages and the PS-ON if you install the replacement main board you bought?
BTW on post #17, you indicate of having 3.3V at the power switch, but does it change state when the power switch is activated?

the readings are from the replacement boards. on the power switch I am getting 2.3, not 3.3 as I had posted. not sure if that's a typo, but I am getting the 2.3 volts back to the board on J6 pin 8. J6 goes to power switch,volume,source..etc, but no voltage on ps_on when power switch is pushed

[budm]

Re: vizio

What happen if you use the remote to turn on the TV? We want to make sure it is not the power switch problem, to have two main board acting the same way is odd unless the replacement board is also bad.

[markmac3]

Re: vizio

What happen if you use the remote to turn on the TV? We want to make sure it is not the power switch problem, to have two main board acting the same way is odd unless the replacement board is also bad.

I get the same results using remote. I checked the pins on the remote sensor which is hooked to the power switch board. had 3.9v on one pin, it would drop the voltage when pressing the remote power button, nothing stable to read but it got no lower than 3.3. also checked J6 and on pin 5 it had the voltage drop like the remote sensor

[markmac3]

Re: vizio

Just got another Tcon board,and like the Bob Segar song, still the same. I unsoldered all caps, one at a time, to check, found a couple out of the 10%range, replaced them and still nothing. Thanks budm an ivtec for your help really appreciate it.