Dynex DX-L40-10A Won't turn on.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I'll see what I can find locally tomorrow and start with c811 and c812 and go from there.

[R_J]

Re: Dynex DX-L40-10A Won't turn on.

I guess you don't have any scrap boards around to find a 10µf cap

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

Got 2 new caps in for c811 & c812 with new readings.

c811 reads 11.08vdc
c812 reads 4.77vdc
c814 reads 15.45vdc
c838 reads 13.84vdc
filter cap reads 384vdc

Do I need to replace c814?

[R_J]

Re: Dynex DX-L40-10A Won't turn on.

The voltages look better, C812 still seems low, check the two diodes VD813 & VD814. It would'nt hurt to replace C814

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

vd814 reads 4.77
vd813 reads 11.04

I'll swap that last cap out rq.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I swapped out c814 and there's minor change.

vd813 reads 11.11
vd814 reads 4.75

[R_J]

Re: Dynex DX-L40-10A Won't turn on.

VD813 are diodes, check them with your meter using diode check. Or if you want to, you could try swaping the diodes around. Swaping the caps will do nothing (unless they were not new caps?)

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

vd813 and vd814 both check out good with a reading of .497 for the diode setting.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I decided to spend the $ for a new PS board. I should be able to track down the offending part if I have a good board for reference. When I find the bad part that ones going in the trash and I’ll have a board of spare parts for when it goes bad the next time.

[nomoresonys]

Re: Dynex DX-L40-10A Won't turn on.

Good idea, let us know how you get along.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I got the new PS board yesterday and got it hooked up today. The main filter cap has 387vdc across it but with it plugged into the 2nd board the tv still doesn't power up. I've also powered it up with the resistor and there is a difference when I plug it into the outlet, with the resistor in I hear feedback in the speakers when I plug it in. It doesn't make that sound when I have it plugged into the 2nd board and not the resistor.
I'm guessing I have multiple issues with this tv.

[nomoresonys]

Re: Dynex DX-L40-10A Won't turn on.

Check the voltages of the connector on the new board with everything hooked up, see if you get the same as the original board, test procedure #3 below, try to do it just as instructed.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I'm not sure what readings I'm supposed to be getting but I see zero difference on any pin when I try to turn it on, this TV has a touch pad and remote to turn on, with the remote or touch pad.

Since it won't power up or turn the backlight on with the new PS board I'm now having to track down the issue on the main board. Any ideas what I should check there first?

[nomoresonys]

Re: Dynex DX-L40-10A Won't turn on.

Some testing there: https://www.youtube.com/watch?v=ocqnqmBxiqY

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

In my preliminary inspection of the caps on the main board I found one I hope is the problem with a low vdc.

CE9 reads out 1.2vdc. That's pretty low for that large cap compared to the smaller one next to it that reads 5vdc.

I can't really follow the circuit path on the top of the board and there's nothing on the bottom. Is there anything else before it I should be trying to verify?

As far as the regulators go they all look like 117's so I couldn't say what the v should be at each.

[R_J]

Re: Dynex DX-L40-10A Won't turn on.

That voltage is correct, it is the 1.1 volt supply.
Shopjimmy does offer an eeprom for this model, maybe thats the problem. You can try freezing the eeprom ic and see if the tv will turn on.
You would need to unplug the tv, freeze the ic, wait a 5~10 sec, plug the tv in and try turning it on, this sometimes works but not always.
I also see that there is a firmware file available for this model.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I just tried the freezing trick and had no results. Are there any base readings I can check on that eeprom?

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

Poking around checking cap voltages I came across cap CE48 with a reading of 0.017vcd. I checked the IC N21 right next to it and on the left side it has 12vdc and on the right its 0.017vdc. Could this be the suspect?

[R_J]

Re: Dynex DX-L40-10A Won't turn on.

N21 is a mosfet, used as a switch to control the +12v on the lvds cable to the t-con/panel. It is controlled on pin4 (gate) If the tv is not turning, 0 volts on N21 drain is normal.
As for the eeprom, you can check if it has vcc but thats about it. If you have a programmer, (CH341A) you can try reprogamming a new ic, I believe there is a bin file for this model.

[Funda]

Re: Dynex DX-L40-10A Won't turn on.

I ended up just buying a replacement main board and it's working again. Thanks for all the help in my long term struggle. lol