Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

[dailafing]

There are so many posts online about how Samsungs were identified by the ticking or clicking relays, and everyone said it was almost always a bulging cap, or failing that it was a MOSFET...

Well, my Samsung has just joined the fun, but I was surprised to find that upon disassembly, everything looks fine to me...

No dry joints, or missing solder...
No bulging caps...
No scorching or burning
No cracked resistors or anything..

In fact, by my eye, visually everything is find save for some cobwebs and dust...

So I'd like to kindly refer to the experts here, and ask for a second opinion.
ideally I don't want to have to un solder everything and test it manually, because
1) its a pain, and
2) I don't really know what im doing.

I know how to be safe, and I've had my initiation when working on a live iMac pranging myself with 240v to earth via my chest
(Right hand earthed by holding metal LCD bezel, and left knuckle touching live 240v feed)

Please see video and pictures of my powerboard, (BN44-00162A, PSPF531801A, W2A)

Thanks

https://www.youtube.com/watch?v=4R4cOi2Yr04

[Jidis]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

I'm in the same boat as Dailafing here and was asking about the same thing on the BN44-00356B board from mine. I went ahead and ordered a BN44-00356A replacement last night, but like him, just can't help but wondering if the majority of these things have something in common with regard to failures and someone out there is making a killing by cycling "refurbs" out of all the thrown away dead boards.

The guys who sell the fifty dollar repair kits say something about the kit containing "a couple MOSFETs and a couple electrolytics" or something, but aren't any more specific. It looks like most of the TO-220 stuff on my board is in plain sight. If they're not prohibitively expensive, I'm tempted to throw them all on my next Mouser order just to know what the heck it was that actually died.

Take Care

George

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

Yo man, thanks for your input.

What's TO-220?

Anyway, yeah I recon this is a really common fault. Everyone is talking about the tv's failing on the same issue.

I'm wondering if my mosfets are gone? Since all the caps are ok? (Look ok)

But this chap I spoke to seemed to know it wouldn't be the caps...
Almost like the LCD samsungs are known for the caps going, and the plasmas are some other part that goes.... He wats about £40 to fix it "if it's what he thinks it is" and his advert was geared towards "the common samsung plasma fault, where it clicks but never comes on"

If someone knows what this issue is, please let us know...

Thanks

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

TO-220 is a package format for the transistors and diodes mounted on the heat sinks.

You should not shot gun replace parts like that unless you intend to replace every part on the power board because in many cases, when the transistors fail it takes out other components like surface mount resistors and the driver ICs.

You should check all the fuses on the board are good, most likely you will find a bad one. I had a similar power board for the 50" model and the two transistors to the left of this image were bad. The biggest ones. In addition I replaced four surface mount resistors, two surface mount diodes and a fuse.
https://www.badcaps.net/forum/attach...8&d=1393769531

[Jidis]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

What's TO-220?

Just the style of "package" that most of the important looking active parts are in on my board (the black rectangular things with the flat back often attached to a heatsink). Other than that, there are a couple little opto-isolator looking guys and a random chip or two, then a whole bunch of stuff which might be checkable with regular multimeter gear.

On the other hand, the back has a bit of surface mount action, but not many "non-passive" parts. Would still be nice if someone here had some inside knowledge they didn't mind sharing on this subject. I doubt either one of us is looking to "go into business" with it, but rather just want to fix our own board. Then again, I guess you never know who else might be reading these.

Take Care

Looks like Tom beat me to the package definition. BTW Tom- my fuses were all checked first, and they're all intact. I'm still sitting here with fingers crossed, hoping this new PSU brings my set back up though. It'll be a shame if that's not even the culprit.

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

TO-220 is a package format for the transistors and diodes mounted on the heat sinks.

You should not shot gun replace parts like that unless you intend to replace every part on the power board because in many cases, when the transistors fail it takes out other components like surface mount resistors and the driver ICs.

You should check all the fuses on the board are good, most likely you will find a bad one. I had a similar power board for the 50" model and the two transistors to the left of this image were bad. The biggest ones. In addition I replaced four surface mount resistors, two surface mount diodes and a fuse.
https://www.badcaps.net/forum/attach...8&d=1393769531

Hi tom, im glad to hear you had a similar board to this.
I've read in my studies on this that there is a way to just put the AC into this, and then test each of the pins for a voltage?

Could you tell me if this is a good idea, and might help me trace my problem?
I have a standard multimeter at the moment, and really want to start getting a better idea of what is going on here.

I just checked every fuse, and they all check out at about 2-5 ohms, out of circuit.

Also read somewhere about disconnecting certain parts to see if I get 'something' on the screen?

Perhaps if you gave me some instructions on what to try out? I can report back to you.

Id really like to fix this myself, the sense of achievement would be amazing as I've always liked electronics, but never really got into the big stuff like this...

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

I wouldn't do that.. Applying random AC will likely destroy things!

First, you should try to observe the fault(s) with the power board.

Using a digital multimeter, check the voltage on the Vs/Va output of the board. Is it matching the ratings printed on the back panel of the TV?

If not, try unplugging the Y-main and X-main boards, see if the voltages come up then.

If they do you have a bad Y-main or X-main, you can then try with one board and see if it will fire up with one board removed. With Y-main removed you will get no picture. With X-main removed the picture will be dull, purple tinted or fade in like a lava lamp.

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

Nooo, I meant ac into the right place to test the voltages that the board is producing.

Ok.... So I'm gonna be really carful and ask for clarification in everything to make sure I'm doing it right. I don't wana die, I dont wana get zapped and I don't want to make things worse.

Ok, so how do I check the vs and va. The label says vs= 205 and va = 63? I mean literally, can you gimme exact instructions just to make sure I don't make a n00b mistake.

Also, about unplugging each of the x/y boards. Should i refit the whole board and all connectors, then just remove the power from each if the left and right hand boards?

I gotta ask to make sure, please assume i know nothing for now

Again, thanks for your help.

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

Can you supply a picture of your multimeter so we know what you have?

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)



thanks

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

OK, do you see some little stand offs or domed points marked Vs and Va on your power board?

Set your meter to 500V DC, press red probe onto the point, black probe onto the chassis, this is with the TV powered on and clicking. Record the reading while it clicks on and off.

Do this for both Vs and Va.

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

ok re assembling now, and will let you know the results...

I'm a bit scared if im honest, I feel the heart pumping...

Will post a pic of the points I intend to test before proceeding.

Glad to know I got you on stand-by ("See what I did there - stand-by")

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

OK, do you see some little stand offs or domed points marked Vs and Va on your power board?

Set your meter to 500V DC, press red probe onto the point, black probe onto the chassis, this is with the TV powered on and clicking. Record the reading while it clicks on and off.

Do this for both Vs and Va.

please confirm for me that all wires should be reattached as though I had never opened it before during this test...

thanks

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

They should be. TV in original state.

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

Ok, so I got top centre and bottom right screws in to save time, the board is secure.

Please see below pic, there are two VS and two VA right next to each other?

So...
I'm going to connect all the leads back in now,
power it up with the back off, with all of the leads connected including the VS&VA power cables.

Rest the black lead of my DMM to the body, or other ground point, and then connect the red wire of my DMM to the collar of the VS&VA leads (Individually on separate occasions) that fit into the white plastic plug that fits to the board...
Then let you know what's happening

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

There is a point marked VS-TP and one marked VA-TP. You should test there, with those connectors installed as normal.

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

There is a point marked VS-TP and one marked VA-TP. You should test there, with those connectors installed as normal.

You literally sent that just in time....

I'm having difficulty finding the VS-TP or VA-TP
I guess the TP is test point?

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

Ok done VS-TP....
https://www.youtube.com/watch?v=GWUlqiIBnuM

No voltage whatsoever....

Doing VA-TP now... if I can find it...

[tom66]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

OK, now unplug the X- and Y-main board power.

The X- and Y-main boards connect to the power board through those connectors with Vs and RTN on them, note this is NOT the one with Va and RTN and 5.3V on it.

Then see if the voltages rise on VS-TP.

[dailafing]

Re: Power Supply Failed - Samsung Plasma PS-42Q96HD (BN44-00162A, PSPF531801A, W2A)

OK, now unplug the X- and Y-main board power.

The X- and Y-main boards connect to the power board through those connectors with Vs and RTN on them, note this is NOT the one with Va and RTN and 5.3V on it.

Then see if the voltages rise on VS-TP.

Should I check the VA-TP first, or is it not needed now?