Samsung LE37B650, gamma?

[Behemot]

Got this one with T370HW02 TCon with AS15-HF and ordinary picture brightness problem. From 14 pins 1-3 are at ~15,5 V, than it drops to 11 V and decreases normaly. I guess pins 2-3 are faulty and should be lower, right?

[tom66]

Re: Samsung LE37B650, gamma?

You should check gamma voltage points not chip directly. A picture of the fault would also help.

[Behemot]

Re: Samsung LE37B650, gamma?

Sure, how do you think I'd measure those tiny leads? It looks OK optically.

Image at http://www.wisiny.com/media/catalog/...0HW02%20VE.jpg, measured VG1-VG22.

[Alastair E]

Re: Samsung LE37B650, gamma?

Err--I Think Tom meant a Picture of the set's Picture--Illustrating the Fault, not a pic of the T-Con!

[tom66]

Re: Samsung LE37B650, gamma?

Could you share full voltage set? The monotonicity requirement is only a basic test. The voltages should also be symmetric about the mid point.

[Behemot]

Re: Samsung LE37B650, gamma?

Oh, stupid me Here you go. Quite a milky one, eh?

It goes like (rounded, I don't remember so many numbers)

15
15
15
11
13
8
8
7
7
5
4
2,5
0,4
0,3

Seems that also no. 5 is bad.

[Alastair E]

Re: Samsung LE37B650, gamma?

OOoh--That is Horrible!

As Tom suggests--the Voltage-readings should give some indication of the fault...

[Behemot]

Re: Samsung LE37B650, gamma?

I am idiot, soldered wrong direction. Heard a spark, only LED was still on. OK, will try for second time, new chip, hopefully nothing else is bad…maybe even this one is OK but I am not taking the risk since the soldering is the worst on it

Anyway, there was chip version with solder tab, I have full-plastic package only, will have to create some cooling for it or heat transfer to the metal cover, problem is it is at least a centimeter above the chip

[Behemot]

Re: Samsung LE37B650, gamma?

Second try is a success

After like 20 minutes it was just slightly warm. Do you think I should place there just some small heatsink or I can leave it be as it is, without cooling?

[tom66]

Re: Samsung LE37B650, gamma?

I would use a heatsink myself.

[Foppel]

Re: Samsung LE37B650, gamma?

Dear all,

thanks for this thread. I repaired my LE37B650T2P with the same problem. It was really hard to remove the old AS15-HF Chip. I tried with my rework station from two sides, but no way. Then i used a dremel tool to remove the chip. It worked for me. I removed two little pads from the board Then i used two little wires to connect it directly to the chip. I tested the tv and everything is working fine. I ordered a cooler for the raspberry pi to use it with the AS15.