Samsung HP-T5054 ysus and buffers

[JeffJ]

Had this tv given to me, pulled it apart and the tv powers up and sound works with out the ysus plugged in. Anyways...

The ysus had 1 shorted AP88N30W FET, 1 Shorted SK2873 FET and a shorted B20NK50Z FET. Everything else checks out, tested the resistors and zeener that commonly go as well and they are fine.

The upper y buffer had one of the FE3407F chips physically blown out, so i removed it and tested the buffer again for a short and it appears to be ok. The lower buffer tests free of shorts.

I am not really looking to dump a whole lot into this tv, as i am looking to donate it to some one who is down on their luck and has no tv.

The ysus I am confident that repairing these blown parts will fix it up just fine. However Question is, can i get away with replacing the single chip on the buffer and adding some heatsincks, or am i just looking to cause the rest of the chips to pop, or the lower to pop thus blowing the ysus out again. It's not a question of not having the tools or skill, as i am confident with these, its a question of am i cheeping out too much on the upper buffer here?

[tom66]

Re: Samsung HP-T5054 ysus and buffers

Usually just the first addressed IC fails, or the top one in this case.

[JeffJ]

Re: Samsung HP-T5054 ysus and buffers

Usually just the first addressed IC fails, or the top one in this case.

Hit the nail on the head. everything else looks good, no dead shorts any more. I think I'll give it a go and replace that IC, re-insulate the pins and throw some heatsincks on it. Unless you advise I'm wasting my time.

[tom66]

Re: Samsung HP-T5054 ysus and buffers

I think it should work. Those buffer ICs are usually available <$10 each.

[JeffJ]

Re: Samsung HP-T5054 ysus and buffers

I think it should work. Those buffer ICs are usually available <$10 each.

Thanks for the help, i ordered 2 of all damaged parts for under 15 bux. If it all works out i get to have that warm and fuzzy feeling of helping out someone in need.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

I think it should work. Those buffer ICs are usually available <$10 each.

I've heard that replacing a single buffer IC is a ticking time bomb, as the other ICs could also be on their way out. What has your experience been with these ICs? I'm contemplating buying one of these Samsungs with a bad Y-Sus mosfets and a bad buffer IC. I'm comfortable changing the ICs, since I've done a few.

[tom66]

Re: Samsung HP-T5054 ysus and buffers

The ICs don't wear out. The Y-main does and the failure of it damages the Y-buffer. I would replace all the FETs in the same bank as the blown one, and one buffer IC.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

The ICs don't wear out. The Y-main does and the failure of it damages the Y-buffer. I would replace all the FETs in the same bank as the blown one, and one buffer IC.

Really??? That's great news. Hopefully, I'll pick up the Samsung tomorrow. Thanks!

[tom66]

Re: Samsung HP-T5054 ysus and buffers

The ICs themselves are quite reliable.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

The ICs themselves are quite reliable.

Ok. Well, I'm guessing the previous owner tried to fire this TV up more than once, because I have four blown ICs on the buffers: Two on each buffer board Also, the B20NK50Z mosfet on the Y-Sus is badly burned; the board appears salvageable, though.

When you mentioned changing the whole bank of transistors, were you talking about the 88N30Ws on the heat sink? I haven't tested any components yet to confirm whether they're working.

[tom66]

Re: Samsung HP-T5054 ysus and buffers

All five transistors on that bank should be replaced.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

All five transistors on that bank should be replaced.

So, are you saying I should replace them regardless of whether they test ok?

[tom66]

Re: Samsung HP-T5054 ysus and buffers

They may have suffered secondary damage that is not obvious under the test current of your meter. But you may get away with replacing just one.

[tocold4u2]

Re: Samsung HP-T5054 ysus and buffers

how easy is it to remove the ic`s on the buffer board and replacing? i have 2 sets of boards that just need a ic replaced ? i have been wanting to try to replace them? any special tools needed, like a hot air station ??

[tom66]

Re: Samsung HP-T5054 ysus and buffers

Yeah, you'd best use a hot air station. It is possible without, but very difficult. A paint stripper may work, if you can keep the temperature from going too high.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

They may have suffered secondary damage that is not obvious under the test current of your meter. But you may get away with replacing just one.

Ok, thanks.

Yeah, you'd best use a hot air station. It is possible without, but very difficult. A paint stripper may work, if you can keep the temperature from going too high.

On some of my earlier attempts, I used a heat gun to remove the ICs. I ended up melting plastic on nearby connectors. My hot air station was down at the time, and I may have been a little careless and impatient. A hot air station is definitely the way to go, though.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

Ok, after I removed the melted mosfet "guts" from the back side of the board and cleaned up the pad a little, I found that one of the traces is damaged. I have a conductive pen, so I was going redraw it. Do you foresee any issues? It appears to be a ground.

[tom66]

Re: Samsung HP-T5054 ysus and buffers

I wouldn't worry it looks like that whole pad is grounded. You can verify it with a meter.

[capkid]

Re: Samsung HP-T5054 ysus and buffers

I wouldn't worry it looks like that whole pad is grounded. You can verify it with a meter.

Ok, thanks. I didn't think it was a big deal, but I wanted to make sure.

[retiredcaps]

Re: Samsung HP-T5054 ysus and buffers

On some of my earlier attempts, I used a heat gun to remove the ICs. I ended up melting plastic on nearby connectors.

I use a heat gun and use Kapton tape to protect the surrounding components.