e701i-a3 no picture but backlights

[tjmethod]

Re: e701i-a3 no picture but backlights

Well is there a short showing up in the COXA transistor?

Hey there freak new new magic transistors are in and I only had time yesterday to replace the one's on the 2 of the 3 t-cons I have the 3rd one is still in the tv. I recall, you had replaced your COXA with one of these from a Sony t-con that you had and the values are higher and they handle more power from your and is what has been working without issue on one of your 70's? I will be doing g so e testing later today- I had a hell of a time resolder the new ones in place. Just positoning was a task and a magnifying glass is a must! I even added a tiny bit of solder but wasn't easy even though I sharpened the tip with a dremel. I'm crossing my fingers

[tom66]

Re: e701i-a3 no picture but backlights

If you're talking about sharpening the tip of your soldering iron with a dremil, that pretty much destroys the tip as that has a fine alloy layer that allows the iron to work properly. You'd best just get a new tip, they're not very expensive anyway (a few dollars a piece in most cases.) And that way you can get the right size tip, I prefer using an angled flat tip.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Good deal. Just remember to to test tcon board without either ribbon connected to the output just the LVDS cable connected first to verify proper working voltages before you proceed

[tjmethod]

Re: e701i-a3 no picture but backlights

If you're talking about sharpening the tip of your soldering iron with a dremil, that pretty much destroys the tip as that has a fine alloy layer that allows the iron to work properly. You'd best just get a new tip, they're not very expensive anyway (a few dollars a piece in most cases.) And that way you can get the right size tip, I prefer using an angled flat tip.

Thanks Tom- I actually bought a 60 watt iron thats got adjustable dial that had a sharp tip but it wasnt sharp enough as the one I sharpened which does work anyway but I'm sure you're totally right. I have no formal training in soldering other than past experience. My problem is being able to see the damn things since they're so small

[vinceroger69]

Re: e701i-a3 no picture but backlights

Hey there freak new new magic transistors are in and I only had time yesterday to replace the one's on the 2 of the 3 t-cons I have the 3rd one is still in the tv. I recall, you had replaced your COXA with one of these from a Sony t-con that you had and the values are higher and they handle more power from your and is what has been working without issue on one of your 70's? I will be doing g so e testing later today- I had a hell of a time resolder the new ones in place. Just positoning was a task and a magnifying glass is a must! I even added a tiny bit of solder but wasn't easy even though I sharpened the tip with a dremel. I'm crossing my fingers

in the first picture of the tcon under the number 163 by the big chip pins theres a blob of solder that maybe shorting some pins out just make sure you remove it before powering it on.

[tjmethod]

Re: e701i-a3 no picture but backlights

Good deal. Just remember to to test tcon board without either ribbon connected to the output just the LVDS cable connected first to verify proper working voltages before you proceed

Well I found the ohm meter that I was using crapped out even thought the battery and fuze were good so I bought a new digitial multi meter. I tested a couple 1.5 AA batteries- one new and one not new but good. The readings were around 1567 on the new one and 1534 on the other. I got all 3 t-cons suited up with the new QF transistors. With each board hooked up, then the LVDS cables hooked up only, then the power cable plugged in and they all read the same. In ohm mode with the dial on 200k with the negative probe on the left middle single leg and the red probe on the top and bottom legs as shown in the pictures, I only got 2.0 on all three boards. I get the same reading with the red probe on the + of the silver capacitor still yet on 200k setting in ohms- on all three boards, but no other setting on the meter brings up a reading. I dont want to hook up the panel ribbons or power it on until I can do some tests that make sense- any idea where I go from here?

[tjmethod]

Re: e701i-a3 no picture but backlights

No reading with black probe on left middle leg and red probe on right lower leg

[freakaftr8]

Re: e701i-a3 no picture but backlights

You should be checking in DC mode on the meter. Ohms won't tell you if you are getting power. Black probe to screw terminal on tcon. Red lead to + side of the capacitor. You can also test voltage at the inductors. 3r3 , 100, and 4R7.

Should see 1.0v 3.3v and 15v or so.

[tjmethod]

Re: e701i-a3 no picture but backlights

You should be checking in DC mode on the meter. Ohms won't tell you if you are getting power. Black probe to screw terminal on tcon. Red lead to + side of the capacitor. You can also test voltage at the inductors. 3r3 , 100, and 4R7.

Should see 1.0v 3.3v and 15v or so.

Not sure you may not have picked up that I have no experience using a volt meter but it seemed the only setting theat I could get a reading was in ohm's on 200k- heres a picture of the exact same multimeter I bought only in black- what should I set the deal on and should I put the red probe in the 10A slot?- also I did put the black probe on the screw and red on the + side of the red cap and also got a reading of 2.0 in 200k on ohm's- somethings obviously wrong if I'm only getting readings on 200k in ohm's. Where would DC be or does this multimeter not have that? I hate to sound like an dumbo but I just haven't used a volt meter much.

[tjmethod]

Re: e701i-a3 no picture but backlights

Silver cap not red

[freakaftr8]

Re: e701i-a3 no picture but backlights

Ok. Black probe in COM socket red probe right above it. Not the top socket. That's used for a different application. Have the selector switch set in the top left section in 200 DC mode.

Now with tcon connected to the LVDS cable only, run 2 screws into the tv securing the tcon to the tv. Don't worry about the metal cover being there. Now power up tv.

Put the black probe into one of the holes that are not occupied by a screw for your ground.

Now with the tv powered on, use the red probe and carefully probe those round matte grey canisters on the board. They say 3r3, 100 and 4r4 or something close to that.

Are you getting any voltage?

[freakaftr8]

Re: e701i-a3 no picture but backlights

When it comes to trial and error I can't emphasize enough that you must keep your hand on the plug ready to pull the plug if nothing shows up on the screen after you power it up in 3 seconds once you power the TV up you should immediately see the back lights come on along with the silver v in the center of the screen if you do not see this in 3 seconds don't leave it plugged in you will blow up your tcon if there's something wrong still with the panel.

[Tmal0146]

Re: e701i-a3 no picture but backlights

So I got my new tcon board in and plugged up the LVDS cables and powered it up without the bottom ribbon cables plugged in. Tested voltage on the three canisters labeled 3r3, 100, and 4r4. Got 3.3, 12.57, and 0. I'm thinking my "new" board may not be as advertised. I also noticed while I was checking the voltage a small puff of smoke came from somewhere on the board. I also did the ohms test on the transistor and got like 2.45 on the top pin and 10.6 on the bottom pin. Bad board?

[Tmal0146]

Re: e701i-a3 no picture but backlights

And tried the new board just to see and got no v on the picture. Tried unplugging each side of the drivers also and still have nothing.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Huh. I dont know what to tell you. Did your probe slip off and short something out? I would request an exchange on that board. You should have has read 12v 3.3v and 1.0v IIRC.

[Tmal0146]

Re: e701i-a3 no picture but backlights

No. I don't even think I was touching anything when it did that. But the transistor ohmed that way before all that happened. I checked it first.

[freakaftr8]

Re: e701i-a3 no picture but backlights

Sounds like you got a bad tcon from the start. I ran into this 3 times on ebay.

[Tmal0146]

Re: e701i-a3 no picture but backlights

It should have ohmed 500 on one pin and some crazy high number on the other though right?

[Tmal0146]

Re: e701i-a3 no picture but backlights

I ordered this one from encompass. I'm hoping they will allow me to return it or exchange it for another one that may possibly work.

[freakaftr8]

Re: e701i-a3 no picture but backlights

It should have ohmed 500 on one pin and some crazy high number on the other though right?

Yes