Dynex DX-L40-10A

[Mr Bill]

Re: Dynex DX-L40-10A

The input voltages are off too. In post 17 i put the in/out and what i'm getting for N1, N3 ect ect. I pulled every cap off the power supply and they are all in tolerance. I even checked the esr and most were 0.01 except for the 4.7uf 450v cap which was 5.84ohm. Would you bet the main board needs to be replaced? I have this feeling that trying to diagnose one little component will take months for me to find where i can just pick up a main board for $50 plus shipping.

[budm]

Re: Dynex DX-L40-10A

$50 is cheap, and at this point, it does look like bad main board from the symptom you are having.

[Mr Bill]

Re: Dynex DX-L40-10A

I got the board and the tv fired to life.

[Mr Bill]

Re: Dynex DX-L40-10A

It didn't last long. I had it running in the basement with the volume down on 2. The snow sound came on and the screen went blank. The sound coming from the speakers was like if the volume was all the way up. The keyboard wouldn't turn the tv off, i had to unplug it. I waited a minute, plugged the tv in and now all the channels are in black & white with some wavy's (noise) in the display. I turned it off and i am going to wait about 30 minutes to cool down and see if the black and white picture remains due to heat.

Any thoughts?

[Mr Bill]

Re: Dynex DX-L40-10A

After the tv being off for about a hour i turned it back on and the color has returned. I'm going to take voltage readings now and after it fails.

[budm]

Re: Dynex DX-L40-10A

So the new board has different symptom than the old one (sound from speakers, lose control of the push buttons, backlights is on without TV on). This is tough.

[Mr Bill]

Re: Dynex DX-L40-10A

The new board seems to be doing what the old one was but at this point it still turns the backlight on when the tv is turned on and i can turn the set off with the keypad whereas before i had to unplug it.

Here is a recap of the situation:

with the new board the tv turned on, backlight came on, everything normal. After some time the tv went pop and the display went away but the backlight stayed lit up and getting the snow sound really loud. The keyboard wouldn't work. I unplugged the tv and waited a few minutes. Plugged it back in and the tv did turn on, backlight came on but the display was in black and white, no snow sound. The keypad did work just black and white. So, i turned it off for around a hour. When i turned it back on the picture wa fine. I'm wondering if this is a thermal issue.. Haven't ran the tv again to see how long it will go before doing it again.

[Mr Bill]

Re: Dynex DX-L40-10A

The tv only lasts about 15 minutes before the display goes out. I checked the voltages and everything is still the same. I did notice that the tcon cage is pretty warm. Alot warmer than the power supply. I am going to remove the cage and try to setup a fan directly on the tcon board only to maybe rule out if it is a thermal issue.

[Mr Bill]

Re: Dynex DX-L40-10A

After running a fan on the tcon area the tv stays on. So the only conclusion i can come up with is the tcon is overheating and shutting down which is causing the main board to freak out. I'll order a tcon and see what happens.

[tibimakai]

Re: Dynex DX-L40-10A

can't you put a heatsink on that component?

[budm]

Re: Dynex DX-L40-10A

You can but more likely something is failing, and will probably fail completely later. I did it before and it lasted about 6 months, I just used the Gel Superglue and check the tempearture with my Thermal gun.
http://s807.photobucket.com/albums/y...%20LTV-32W3HD/

[Mr Bill]

Re: Dynex DX-L40-10A

I ruled out the tcon board. Before i had a fan blowing on the entire back of the tv just to see how long it would go. I then setup a shoot with a computer fan blowing air directly on the tcon. I baffled around the power supply and main board to ensure the air was only hitting the tcon. The tv lost its display at its usual 20ish minutes. I tried feeling around the main board and i don't feel anything warm. I then started feeling around the power supply and the only thing i found was this one transformer that was bad hot. I did one of those touched a griddle flinch moments. The other large transformer was no where near as hot. I'm not sure if its a pfc transformer but i'm going to setup a shoot directly on the power supply tomorrow and if that works, i'll then move to the newly replaced main board.

The thing that baffles me the most is the voltages are very close to the same when its first turned on (cold) and after the display goes out, within .005v

[budm]

Re: Dynex DX-L40-10A

That is the PFC Voltage boost Inductor with sensing winding.

[Mr Bill]

Re: Dynex DX-L40-10A

i've narrowed it back down to the newly replaced main board. If i put a pc fan on the metal cage the tv will run forever. I removed the cage from the bad main board and there is one chip with a heatsink on it and a couple smd elctrolytic caps. I'm wondering if the heatsink is not making a good connection on the chip to remove heat. What is the standard way of putting a heatsink on a chip, just glue it down?

[aspentech]

Re: Dynex DX-L40-10A

Mine was making a weird popping noise, according to the wife. She could only stop it from acting up by totally cutting power. I did some troubleshooting, it powers up, nice blue screen with nothing plugged in except power. After a few minutes of pressing buttons, it locks up,m becomes darker and nothing responds. Is this power supply or main board #122917 that I can only find on Best Buy's "PartStore.com?"

[Mr Bill]

Re: Dynex DX-L40-10A

I'm thinking it the main board. I ran a fine comb through the one i have. The thing that i found odd was every main board that was on ebay at the time from reasonable $80 to outrageous $120 SOLD. So this tells me that the main board in this particular tv fails alot.

On mine after it turned on it wouldn't turn off unless i pulled the power plug.

[budm]

Re: Dynex DX-L40-10A

@bill, can we see what the setup is like on this heatsink? no clips or anything?

[Mr Bill]

Re: Dynex DX-L40-10A

I don't have the tv anymore, i returned it back to a friend of mine. He opted to put a small chipset fan over the chip that was overheating due to the cost of getting another board. I'm emailing myself the picture i took of the chip with the cage removed. I'll post it here in a few minutes.

I just checked ebay and there is a main board right now that has 8 bids and its at $122

[bkwooh]

Re: Dynex DX-L40-10A

How to you add a pc fan?

[emogolf]

Re: Dynex DX-L40-10A

help

plug in tv dx-l40-10a
loud click
red light in front comes on 1 sec
turns to blue light 1 sec
loud click
red light in front comes back on
nothing will work