Seiki se421tt

[heavymachines]

Re: Seiki se421tt

They should be labeled with something like DRV1+, DRV1-, DRV2+, DRV2-, etc.

i will take a closer look when i go into work, it has white glue on it holding the plastic cage to the pins lol, i will scrape it off the spare board to see if there are any label under it....but i am certain those are the led connector but could be wrong will double check...Thanks for the reply and help.....

[budm]

Re: Seiki se421tt

Those 4 small connectors do look like for the LED. You said the TV shutdown after a couple hours, does it act like the power switch is turn off or you lost the backlights but still have sound?
You can monitor the DC voltage on the two caps (450V) in the primary side (just use either cap) and see if the voltage drops down from around 400V to 165V when it goes into shutdown mode.

[heavymachines]

Re: Seiki se421tt

the big one in the center...

[heavymachines]

Re: Seiki se421tt

Those 4 small connectors do look like for the LED. You said the TV shutdown after a couple hours, does it act like the power switch is turn off or you lost the backlights but still have sound?
You can monitor the DC voltage on the two caps (450V) in the primary side (just use either cap) and see if the voltage drops down from around 400V to 165V when it goes into shutdown mode.

well i am using a laptop to drive the display via the VGA connector, hence no way of telling sound, it will just shut off the display but power light will stay on , and it will not turn back on till i let it sit for awhile, but it will come back on....

[heavymachines]

Re: Seiki se421tt

Which transformer that gets hot? The large one in the center or the top right for the PFC.

Large one in center, the biggest one of the three smack dab in middle....

[budm]

Re: Seiki se421tt

Look like you will need to get a can of cold spray for electronics troubleshooting or use canned air duster upside down and start cooling down component on the power board and see if you can pinpoint the trouble parts.

[heavymachines]

Re: Seiki se421tt

Look like you will need to get a can of cold spray for electronics troubleshooting or use canned air duster upside down and start cooling down component on the power board and see if you can pinpoint the trouble parts.

i do have canned air at shop, so what should i do run it till it shuts off then spray different areas till it decides to fire back up?

[heavymachines]

Re: Seiki se421tt

i do have canned air at shop, so what should i do run it till it shuts off then spray different areas till it decides to fire back up?

also want to mention it seems only the transformer gets hot very hot, could something be over volting it or there is too much resistance to whatever that transformer drives.....

[budm]

Re: Seiki se421tt

Something may be drawing too much current, that transformer looks like it produces the voltages for the LED backlights, may be the 12v for the sound, and other voltages as well.
I would expect the heat sink on the output side of the transformer will get very hot as well since all the current will have to flow through the rectifier diodes mounted on that heat sink as well.
I am not sure if the power supply will shutdown if you disconnect the LED connector, if it does stay on, then you can disconnect 3 and run just one string and see if the transformer will run much cooler. I do not expect the total current draw by the LEDs will be more than 20 Watts.

[heavymachines]

Re: Seiki se421tt

Something may be drawing too much current, that transformer looks like it produces the voltages for the LED backlights, may be the 12v for the sound, and other voltages as well.
I would expect the heat sink on the output side of the transformer will get very hot as well since all the current will have to flow through the rectifier diodes mounted on that heat sink as well.
I am not sure if the power supply will shutdown if you disconnect the LED connector, if it does stay on, then you can disconnect 3 and run just one string and see if the transformer will run much cooler. I do not expect the total current draw by the LEDs will be more than 20 Watts.

will check it out in the morning it 1:25 am here now so i better try to get some sleep cause 7:30 am will be here quick....i will update my findings... Thanks again...

[tom66]

Re: Seiki se421tt

And just looked at that psu again, now,,, is it just me or are they making more simple things then charging us extra? Just that the psu look so empty?

Yes because they have to cut down costs everywhere else to make them within the price bracket of CCFL TVs. So you will find that you get a poorer build quality, and the picture quality isn't much better - if at all. Many newer LED TVs can't even dim the backlight and use inferior LEDs. I see a lot of people buying 720p 32" LED TVs - why not go for a 1080p 32" LCD TV?

[heavymachines]

Re: Seiki se421tt

okay i tried disconnecting led strips and even added fan for the hot running gpu on main board and this thing still cuts off after few hours very weird issue, i checked soilder joints all look good, this thing is weird fellas

[heavymachines]

Re: Seiki se421tt

tried canned air trick no avail however i noticed when it does shut off if you try to restart it right away it will start to boot show the seiki logo then kick back off try few more times and it will boot and run again, could this be bad caps on main board? and it always show stby 5 volts just does not want to start sometimes..till you force it..

[heavymachines]

Re: Seiki se421tt

update..... it got to the point it would not start anymore and i unplugged a string of led and bam it starts again, plug it back in and it will shut off right away it did not do this before, before it would just light up now it just shuts off, so i think it safe to say i have some bad led's so how do i find strings of led and would it cost too much.... new to led, where can i get led strings for this beast.....

[gilly1984]

Re: Seiki se421tt

Are they repairable? Just had a google around for them but all i get is christmas lights

[heavymachines]

Re: Seiki se421tt

Are they repairable? Just had a google around for them but all i get is christmas lights

i am certain it is repairable but i would suspect these led are super cheap and will be short lived, i would imagine it would be wise if i am gonna replace em that they all must be replaced to avoid the issue reoccurring... no luck yet finding led will dig deeper....

[budm]

Re: Seiki se421tt

If you unplug one of the LED string and the TV started up, then you may have cable that may be shorted to the chassis, the LEDs are connected in series, so if one short out, it is not likley to be enough to cause it to draw too much current. One string of LED may have 50 or more LEDs in series.
I unplug the LED cables and measure between pins and also measure between pins and chassis to see if it shows any low resistance reading.

[heavymachines]

Re: Seiki se421tt

If you unplug one of the LED string and the TV started up, then you may have cable that may be shorted to the chassis, the LEDs are connected in series, so if one short out, it is not likley to be enough to cause it to draw too much current. One string of LED may have 50 or more LEDs in series.
I unplug the LED cables and measure between pins and also measure between pins and chassis to see if it shows any low resistance reading.

Thats a very good theory of whats going on and makes total sense i will have to check that out, all the pains of taking panel apart seems to be in order will report results... of course test resistance before the big task.... Thanks budm

[heavymachines]

Re: Seiki se421tt

okay i found resistance from red wire to chassis and like you said very low resistance but enough to upset the tv, anyhow i have it torn down to access the leds and will post what i find it has 2 rows on sides each having one connector and the strip on bottom has two connectors on each end of the strip i will post more of what i find...

[budm]

Re: Seiki se421tt

You have 4 connectors for the 4 LED strings, so right now one of the connector show low resistance to the chassis compared to the other 3? I will wait to see the pictures, most TV with LED will have the LED assemblies on the bottom edge of the screen for the edge-lit TV.
By the way, I see you are working on two TV's.