32" Dynex DXL3210A Won't Power On

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

What components on the main board are simple to test?

Im sorry, but what is the problem again? Have you actually figured out that the PSU is bad?

You can also check the mosfets on the primary side, and on the transformer, you can check to see if any windings are open-circuit.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

I dont think the PSU is bad, since all the output voltages appear on it. The problem is that once the tv is plugged in, the p-on voltages appears consistently. As before when the tv worked, the p-on voltage read 0v until i pressed the power and it rose to 3.3v. As budm suggested it could be a main board problem that is sending out the signal to the psu too early. Also the voltages on the 24v going to the inverter board is appearing too early.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

I dont think the PSU is bad, since all the output voltages appear on it. The problem is that once the tv is plugged in, the p-on voltages appears consistently. As before when the tv worked, the p-on voltage read 0v until i pressed the power and it rose to 3.3v. As budm suggested it could be a main board problem that is sending out the signal to the psu too early. Also the voltages on the 24v going to the inverter board is appearing too early.

Seems like something on the mainboard has its output stuck on, I would trace back the P_ON signal to the chip it comes from.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

I tried tracing the pin back to any connecting components using the continuity function on my multimeter but i couldnt seem to find any before. Ill give it another try once i get home. Theres a closeup photo of the pin and nearby components in post 59 if you have any suggestions.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

I tried tracing the pin back to any connecting components using the continuity function on my multimeter but i couldnt seem to find any before. Ill give it another try once i get home. Theres a closeup photo of the pin and nearby components in post 59 if you have any suggestions.

The picture is on the wrong side of the connector though, I cant see where any of the traces go. It seems like the P_ON goes to an empty spot where a chip should be. Not saying the chip should be there though, some models exclude certain circuits, so they leave the component spaces blank.

And Im not talking about taking a picture on the back side of the board, there are no traces there to track from one of your other photos.

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

Heres a better picture of the connector.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

Heres a better picture of the connector.

Thanks

See the resistor marked R680 next to the header?

Which pin of the resistor is connected to the P_ON pin?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

Measuring from the P_ON pin and the resistor (Red probe on P_ON and black probe on the resistors pin), I get 4.72 ohms on the left side and 5.36 ohms on the right.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

Measuring from the P_ON pin and the resistor (Red probe on P_ON and black probe on the resistors pin), I get 4.72 ohms on the left side and 5.36 ohms on the right.

Hm. What number is written on the resistor?

Is your meter calibrated? (put both probes together, it should measure nearly 0 ohms)

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

It reads 81R, When I put both probes together I get 0.04 ohms.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

It reads 81R, When I put both probes together I get 0.04 ohms.

Ok, you meter is calibrated ok, and the 81R means the resistor is 81 ohms.

Seems almost like its supposed to be a pull-down resistor, but the chip that drives it seems to be shorted. 81 ohms is also low resistance for a pull-down/up resistor.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

Where and what does this trace lead to? (marked in yellow)

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

It leads to X102 and to the back of the main board to some resistors connected to the 5V pin. Following the trace leds to a dead end.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

It leads to X102 and to the back of the main board to some resistors connected to the 5V pin. Following the trace leds to a dead end.

in the third pic, what does the trace goto on the other side?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

actually my mistakes it continues to follow to more resistors.

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

actually my mistakes it continues to follow to more resistors.

Hm, and where do those go? Is there a chip on the bottom of the board?

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

Nope there doesnt seem to be a chip near there on the bottom.

The resistor you mentioned in post 67, R680, when I measure the left side pin of it, I get a reading of 5.30V and 0V if i measure the right side. Would it still be the same trace, since P_ON measures 3.06V?

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

Nope there doesnt seem to be a chip near there on the bottom.

The resistor you mentioned in post 67, R680, when I measure the left side pin of it, I get a reading of 5.30V and 0V if i measure the right side. Would it still be the same trace, since P_ON measures 3.31V?

bah, I guess it is not!

[tieny]

Re: 32" Dynex DXL3210A Won't Power On

yeah this is the problem I mentioned in post 64, having trouble trying to figure out where the P_ON trace leads

[ben7]

Re: 32" Dynex DXL3210A Won't Power On

yeah this is the problem I mentioned in post 64, having trouble trying to figure out where the P_ON trace leads

Yep I know.

If you want you can do the random probing technique, probing pins, components , around the connector. See if you can find anything that has continuity to the P_ON pin.

The only other thing I can think of is that it goes under the plastic connector, on the left side and down to something else, or it goes to a trace in one of the intermediate layers of the board.