AUO t-con - Help me identify and replace transistor please!

[tom66]

Re: AUO t-con - Help me identify and replace transistor please!

Looks like a build version error - they forgot to delete the FET from the version with the jumper in place. Or, the jumper was a bodge added after they made 50,000 boards...

[lookimback]

Re: AUO t-con - Help me identify and replace transistor please!

I found it with Google image search. Was hoping to find one with a part number which was useful. Instead I found a 2 headed coin. Lol

[T30M31]

Re: AUO t-con - Help me identify and replace transistor please!

Interesting find lookimback! Good indication that it is probably safe to try the jumper.

TN245, I will look at the MOSFETs you found tomorrow when I am thinking clearer. Tough day here so right now I am not even sure it would be a P-Channel. If you are going to try a PNP transistor you may want to look for a darlington transistor since they generally have high gain.

One of the good things about the power MOSFETs is that the Drain to Source resistance (RDS) is very low when they are turned on so they can carry a lot of current without generating much heat.

I didn't have any photos of my TCON that were good enough to locate this circuit. I left most of the thermal transfer pads in place and I was focusing on the AS15-G chip so I would have a reference if I messed up anything when I removed it.

[lookimback]

Re: AUO t-con - Help me identify and replace transistor please!

I learned the hard way T30M31, that it is good practice to always take good pics of, at the very least, the area that you are working on. I had a transistor crumble when I was removing it once and had no clue what it was. Fortunately Google image search was good to me that day.

[tn245]

Re: AUO t-con - Help me identify and replace transistor please!

Well guess what guys?? It works!!

I put in this little temporary jumper across Q812. Fired it up and all voltages are good and the picture is perfect.

I'm very happy and satisfied to have resurrected the t-con with all your help. Thanks so much for everyone's contributions! You guys are amazing!

Now, the question is, whether to just run it without the transistor or to keep looking for replacements? What would be the purpose of the switch and might there be any risks in bypassing it like on the V0 board?

As an aside, I said in another thread that the V0 board works with the V2 panel. Well it does for the most part but on certain scenes with lots of uniform greens, blues or browns there's a slight dark splodge middle-top of the screen and regular faint vertical lines visible. Not too obvious but definitely not perfect. I've seen this with two different V0 boards. With this V2 board the picture is perfect - so there must be other differences besides Q812.

[tom66]

Re: AUO t-con - Help me identify and replace transistor please!

I would say you should find a proper transistor. The purpose is probably power sequencing. Without it, the panel could be damaged.

Looks like it must be a PMOSFET. The gate is connected through 60.4 kohms and a speedup capacitor to AVDD. It's held low by a 120kohm resistor. The current flowing out of the base (if it were a base and not a gate) would not be sufficient to switch much current.

This means at 15V quiescent gate voltage will be 5V.

So you would select a PMOSFET with a threshold 5V or lower and could conduct around 1 to 2A. I'd suggest FDN360P.

[tn245]

Re: AUO t-con - Help me identify and replace transistor please!

Awesome Tom. Have ordered a FDN360P.

[T30M31]

Re: AUO t-con - Help me identify and replace transistor please!

tn245, what did you use to take the photo of the TCON with the jumper on Q812?

The detail in your photo is much better and sharper than I have been able to get with my camera. I may need to try my old fixed lens DSLR which I just remembered has a macro setting.

[tn245]

Re: AUO t-con - Help me identify and replace transistor please!

Just my Fuji Finepix s5700. On macro mode with flash. I usually have to be careful with the angle to avoid too much glare from the flash. Works great for close up stuff. I often have trouble getting good pics of entire TVs though. :-)

[tn245]

Re: AUO t-con - Help me identify and replace transistor please!

Tom that MOSFET worked great! Thanks again for your expert advice.

[tom66]

Re: AUO t-con - Help me identify and replace transistor please!

Nice one.

[lookimback]

Re: AUO t-con - Help me identify and replace transistor please!

Glad you got it working.