Toshiba 49L621U

[dick_barton]

Re: Toshiba 49L621U

+1
I'd agree. If there's a led problem then the analogue meter may well be too slow to measure the peak voltage.

[CapLeaker]

Re: Toshiba 49L621U

Can you redo all these measurement's when the TV is in that fail mode?

[dick_barton]

Re: Toshiba 49L621U

The initial post indicated that there was audio but no backlights.
The voltages given appear to support that all the DC voltages are up and running as well as Backlight On and Power On signals.
Now trying to establish what the led voltages read on power up to see if there is a led(s) / led driver fault.

[budm]

Re: Toshiba 49L621U

https://www.badcaps.net/forum/attach...1&d=1524391578
What DC Voltage do you have when measure right between the two legs of the two brown caps (100uF 160Vdc) laying on the side in that LED driver section that is marked with yellow box?

[nomoresonys]

Re: Toshiba 49L621U

BE CAREFUL when measuring filter capacitor, capacitors can carry a DEADLY CHARGE long after tv has been unplugged, can check video below.

[kristapMA]

Re: Toshiba 49L621U

Can you redo all these measurement's when the TV is in that fail mode?

you mean when its fully on? After the logo and it turns black?

[kristapMA]

Re: Toshiba 49L621U

BE CAREFUL when measuring filter capacitor, capacitors can carry a DEADLY CHARGE long after tv has been unplugged, can check video below.

Thank you for the heads up. I will watch the video when i get ready to measure it..

[CapLeaker]

Re: Toshiba 49L621U

you mean when its fully on? After the logo and it turns black?

after the logo and it turns black

[CapLeaker]

Re: Toshiba 49L621U

The initial post indicated that there was audio but no backlights.
The voltages given appear to support that all the DC voltages are up and running as well as Backlight On and Power On signals.
Now trying to establish what the led voltages read on power up to see if there is a led(s) / led driver fault.

Yeah, I know where you are going. I'd like to see the PSon and BLon state when that TV clonks out. Maybe there is a main board issue I'd like to rule out. Carry on Dick!

[budm]

Re: Toshiba 49L621U

BTW, can I get straight shot pictures of the whole bottom side of that power supply board Toshiba PK101W1230I?
Shopjimmy does not have it.

[budm]

Re: Toshiba 49L621U

https://www.badcaps.net/forum/attach...1&d=1524391578
What DC Voltage do you have when measure right between the two legs of the two brown caps (100uF 160Vdc) laying on the side in that LED driver section that is marked with yellow box?

Correction, one of them is 100uF 100V, another one is 100uF 160V.
There should be Voltage on both of them when TV is turned on.

[budm]

Re: Toshiba 49L621U

Standby
1 - 0 - 16v2
2 - 0 - 16v2
3 - 0 - 16v2
4 - 0 - gndp
5 - 0 - gndp
6 -0 - 16va
7 - 0 -gnda
8 - 0 - 16v2
9 - 0 - gndp
10 - 5 - 5v1
11 - 0 - acd
12 - 0 -pwon
13 - 0 -blon
14 - 5 - 5v1
15 - 0 - dim

POWER ON

1 - all the way - 16v2
2 - all the way - 16v2
3 - all the way - 16v2
4 - 0 -gndp
5 - 0 - gndp
6 - 0 - 16va
7 - 0 - gnda
8 - 0 - 16v2
9 - 0 -gndp
10 - 5 - 5v1
11 - 3 acd
12 - just under 4 -pwon
13 - just under 4 - blon
14 - 5 -5v1
15 - 3 - dim

When I tested 10 when the tv was on, the lights (LED) flickered on then off..

is this what you were talking about?

Something does not look right: pin 1,2, and 3 16V2. What does it mean 'ALL THE WAY'?
Pin 8 is also 16V2 but you show '0V', it should show the same as pin 1 ~ 3.
Please verify your measurement.

[kristapMA]

Re: Toshiba 49L621U

https://www.badcaps.net/forum/attach...1&d=1524391578
What DC Voltage do you have when measure right between the two legs of the two brown caps (100uF 160Vdc) laying on the side in that LED driver section that is marked with yellow box?

By legs do you mean in the green circle that I have marked?

[budm]

Re: Toshiba 49L621U

By legs do you mean in the green circle that I have marked?

Yes, need the Voltages of both caps when TV is OFF and when TV power switch is activated, observe the polarity.

[hoodyracoon]

Re: Toshiba 49L621U

interesting thread, i have a 1080p version of the same tv that has the exact same issue, same psu board. i believe it to be a shorted led leading to over current protection based on the fact the middle of the screen is slightly dimmer then the outside in the fraction of a second that the backlight runs, i tested this by taking a video of me pluging the tv in and recording the flash on screen, could be the same issue, if so the led strips like 20$ on ebay

[hoodyracoon]

Re: Toshiba 49L621U

by fraction i mean fraction of a second, probably less then a 5th of a second, definitely not slow enough to verify without a video going frame by frame

[hoodyracoon]

Re: Toshiba 49L621U

either way if its not the LEDs the psu is still only 30$ and ive basically ruled out tcon because the issue persists when i unplug it(and it wouldn't flash the backlight if it was tcon), it doesn't seem likely to tpbe the main board either, but who knows, like i said im voting bad led shorting out the LED driver leading to over current protection

[Diah]

Re: Toshiba 49L621U

By legs do you mean in the green circle that I have marked?

you have TOSHIBA LOGO show on screen at start on. this is much belong to glitch at firmware. as TOSHIBA very known with poor firmware. there are update from August 2017 to this model . download it and follow how to PDFfile with same link. you must match the firmware to your model size in your case 49 to let the INIT_CLEAR.prg work at start up when you plug in the USB first then the electric wall cord

if this didnt help you. i go to judgment the Background edge LED one of line are shorted

[nomoresonys]

Re: Toshiba 49L621U

you have TOSHIBA LOGO show on screen at start on. this is much belong to glitch at firmware. as TOSHIBA very known with poor firmware. there are update from August 2017 to this model . download it and follow how to PDFfile with same link. you must match the firmware to your model size in your case 49 to let the INIT_CLEAR.prg work at start up when you plug in the USB first then the electric wall cord

if this didnt help you. i go to judgment the Background edge LED one of line are shorted

+1, you can solve a lot of problems with a firmware update, learned that the hard way.

[hoodyracoon]

Re: Toshiba 49L621U

didn't see the mention of them seeing the logo, yeah i don't, still think mine is a led issue but get got a multimeter so i can check the led voltages, so ill see, hope its not a eprom issue for me since i don't have a way to flash it unless it has a rs232 header/set of pads