Toshiba 50L5300UC delayed power up

[Mickster]

Hi guys,

I'm having trouble with this LED TV for the past six months.
When I turn it on - nothing happens and then between five minutes and a couple of hours it will come on and work fine.

My research online seems to point in the direction of a bad capacitor but none have popped or leaked.

I'm thinking my next step is to take a leg of each cap out of circuit and test the value but would appreciate feedback from some more experienced techs on this. Should I test anything else first?

Please see attached picture of the power board.

[martyparish]

Re: Toshiba 50L5300UC delayed power up

If you have a multimeter you should test the pins on the connector(J206) and make sure the 5v is there first. If yes, then test PWON while you power it on and see if it changes.(if working correctly it should jump to over 3v.

A more crude method: Try blowing a hair dryer on the caps to heat them up then see if the set turns on right away. Technically it could be another part that "started working" but most likely a cap.

You can even try to isolate certain caps with heat to narrow it down but I'd go ahead and replace all of them($10-$15) if you do any at all.

[ReeceyBurger123]

Re: Toshiba 50L5300UC delayed power up

Doubt its caps that Psu uses top end brands and the Tv is barely even old. I recon you possibly have a motherboard fault here heat the mother board with a hair drier see if the Tv comes on faster.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

If you have a multimeter you should test the pins on the connector(J206) and make sure the 5v is there first.

I have 3.5V on J206. I'm guessing that means something wrong in the rectifier circuit?

[CapLeaker]

Re: Toshiba 50L5300UC delayed power up

Hook everything up, turn it on, and measure all voltages on J206. Use the pin name and your voltage measured in VDC. Do that when the TV acts up and redo it when the TV is running. This way we can figure out what happens or not.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

Yeah sorry - being a bit dumb on that one. Here are the voltages on Connector J206 which all seem to be d.c. apart from NC on pin 8 :

1 12V2 12.5v dc
2 12V2 12.5v dc
3 12V2 12.5v dc
4 GND 0v
5 GND 0v
6 12VA 12.5v dc (I thought this one would be ac)
7 GND 0v
8 NC 1.8v ac
9 GND 0v
10 5V1 5.1v dc
11 ACD 3.5v dc
12 PWON 3.3v dc
13 BLON 0v
14 5V1 5.1v dc
15 DIM 3.2v dc

Thanks for the feedback guys - please let me know if you think there is anything wrong with any of those or if not what to test next.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

I'll try and get the tv running and see what they are then.

[CapLeaker]

Re: Toshiba 50L5300UC delayed power up

I see already there is no BLon signal. That signal comes from the main board and is supposed to turn your backlights on.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

Where should I backtrack to test for that? I've tried finding the circuit diagram for the board but with no luck.

[CapLeaker]

Re: Toshiba 50L5300UC delayed power up

since it took a while for the TV to come on, heat up the main board with a hair dryer and see what happens.

[ReeceyBurger123]

Re: Toshiba 50L5300UC delayed power up

Probably corrupt SPI flash again or failed BGA solder, deffo mainboard fault as I suspected caps on the Psu are very good no need to touch them Let us know what happens when you heat the mobo.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

Hairdryer had no effect after five minutes.

Is there anything here that's likely to be quick and easy or would you say I need to get a whole new board?

[Mickster]

Re: Toshiba 50L5300UC delayed power up

Sorry for the noob questions - I've not worked on tv's before. Is the motherboard the other board here, i.e. the one not pictured?

[budm]

Re: Toshiba 50L5300UC delayed power up

The one in post 1 is the power supply board, the main board is the one with input jacks and tuner jack with cable/antenna connector.

[CapLeaker]

Re: Toshiba 50L5300UC delayed power up

Sorry for the noob questions - I've not worked on tv's before. Is the motherboard the other board here, i.e. the one not pictured?

yep.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

Okay thanks for the help. So should I get a replacement main board or is there any any last things I should test first?

[CapLeaker]

Re: Toshiba 50L5300UC delayed power up

Did you heat the main board up yet? I have the impression you heated the power supply up.

[Mickster]

Re: Toshiba 50L5300UC delayed power up

Sorry - yes I did try that too but it had no effect.

[ReeceyBurger123]

Re: Toshiba 50L5300UC delayed power up

Well the Blon voltage wasnt present so your Mobo is at fault somewhere.

[CapLeaker]

Re: Toshiba 50L5300UC delayed power up

Well, you need a new main board.