Samsung LA40B650T1FXXY BN44-00264A PSU FS801S fuse blowing

[Langfo]

Hi There

I have a short circuit in my BN44-00264A PSU. The FS801S blows immediately when powered up. There are no smells or visibly obvious suspect components. I've been reading through related forum posts and I think I have narrowed down the problem.

I removed components QI820 and QI821 based on a forum thread I was following (but I think this may have been unnecessary in my case). I tried the lamp across the fuse terminals. In my case I have electrician test lamps and these glowed brightly.

A few days later I discovered ~zero resistance across the +/- terminals of BD801S while it was still in circuit. I removed BD801S and still measured the same resistance across BD801S.

Yesterday, I noticed ~zero resistance across the Gate and Drain and the Drain and Source of QP801S. I removed this component and I'm now measuring an open circuit. Does QP801S sound like the faulty component.

Should I replace all the components I have removed or just the QP801S.

Also, I'm in Australia. What is a good place to source components? I have found rs.online.com which have the QI820 & QI821 components. They have a STF11NM60ND. What does the D on the end mean? Is this the same component as STF11NM60N.

http://au.rs-online.com/web/p/mosfet...stors/7612745/

They don't have the Bridge Rectifier TS6B05G, they have a KBU605G

http://au.rs-online.com/web/p/bridge...fiers/6875894/

Has anyone tried alibaba.com or aliexpress.com for components?

Thanks
Mark

[MagicSmoke]

Comparing the datasheets looks like KBU605G will work in place of TS6B05G.

If your fairly sure you did not overheat the components removed, and they test good you can reuse them.

Extra letters on P/N's are usually for inventory control or designate if on tape or loose.

I have had some luck sourcing IC's on ebay.

[budm]

"A few days later I discovered ~zero resistance across the +/- terminals of BD801S while it was still in circuit. I removed BD801S and still measured the same resistance across BD801S" Where is this BD801S? I cannot find in in the diagram.

"Yesterday, I noticed ~zero resistance across the Gate and Drain and the Drain and Source of QP801S. I removed this component and I'm now measuring an open circuit. Does QP801S sound like the faulty component." That means the PFC IC UP801S and the resistor/diode network connected to the Gate of the MOSFET may be damaged also. I would not replaced the PFC MOSFET QP801S, 802S without replacing the IC at the same time or you will take a big chance blowing the new MOSFETs.
BTW, TOM66 website has the diagram for your board

[selldoor]

Originally Posted by budm

Where is this BD801S? I cannot find in in the diagram.

In this SJ picture it is top right corner near the 2 red/orange film caps
http://www.shopjimmy.com/media/catal...264a-top_7.jpg

The OP really needs to post pictures of his own boards

[tw2005]

Originally Posted by Langfo

Hi There

I have a short circuit in my BN44-00264A PSU. The FS801S blows immediately when powered up. There are no smells or visibly obvious suspect components. I've been reading through related forum posts and I think I have narrowed down the problem.

I removed components QI820 and QI821 based on a forum thread I was following (but I think this may have been unnecessary in my case). I tried the lamp across the fuse terminals. In my case I have electrician test lamps and these glowed brightly.

A few days later I discovered ~zero resistance across the +/- terminals of BD801S while it was still in circuit. I removed BD801S and still measured the same resistance across BD801S.

Yesterday, I noticed ~zero resistance across the Gate and Drain and the Drain and Source of QP801S. I removed this component and I'm now measuring an open circuit. Does QP801S sound like the faulty component.

Should I replace all the components I have removed or just the QP801S.

Also, I'm in Australia. What is a good place to source components? I have found rs.online.com which have the QI820 & QI821 components. They have a STF11NM60ND. What does the D on the end mean? Is this the same component as STF11NM60N.

http://au.rs-online.com/web/p/mosfet...stors/7612745/

They don't have the Bridge Rectifier TS6B05G, they have a KBU605G

http://au.rs-online.com/web/p/bridge...fiers/6875894/

Has anyone tried alibaba.com or aliexpress.com for components?

Thanks
Mark

Something i notice is the TS6B05G is TS4B package 3.7mm thick, larger pin spacing.

KBU605G is KBU 7.1 mm thick, pin spacings are 2mm narrower between the legs

you can get a visual idea here http://www.taiwansemi.com/upload/fil...ine/BRIDGE.pdf

looks like an oddball , found RS1005M which also seems hard to find locally.

UTSOURCE takes 3 weeks though from china, some on ebay but expensive way to go. The prices are USD so with the $ sinking keep that in mind.

Also watch out for those on backorder parts at RS, sometimes they are automated and keep refreshing. They had some parts i was after and they were endlessly on backorder and never came in even after 12 months, suspect they became obsolete or discontinued

[budm]

Here is the diagram.

[budm]

Originally Posted by selldoor

In this SJ picture it is top right corner near the 2 red/orange film caps
http://www.shopjimmy.com/media/catal...264a-top_7.jpg

The OP really needs to post pictures of his own boards

Thanks, I see it now.

[Langfo]

Hi There

Thanks for all the replies and sorry for not posting photos of my board or the schematic diagram.

I've taken on board everyone's advice and comments. I've place an order with Utsource.net for the MOSFETs, Rectifier and the PFC chip as well as the diodes feeding into QP801S, QP802S.

I'll update when I receive the parts and solder them in.

[politics]

LG TV 42px5d-eb power not switching on

[nestor_nelida]

Originally Posted by Langfo

I'll update when I receive the parts and solder them in.

What happened finally? I have the same problem.

[motophil]

Too bad @Langfo never posted the solution

I have pretty much the same problem, FS801S blown and zero resistance across +- (or -+) on BD801S while still in circuit, which for my take only leaves four components that might be short - the rectifier BD801S itself, one of the capacitors CP801S and CP802S or the transformer/transducer LP801S (least likely for my take).

On my board the QP801S and QP802S have ~300Ohms measured with a digital multimeter on GS or GD (or SG or DG for that matter), and 0 Ohms for DS or SD - to me that sounds fine, right?

So my next step will be to take the board into work on Monday, more professional tools there, and take out BD801S, and the capacitors CP801S and CP802S to measure them out of circuit. I hope that just one of them blew and nothing else...

- Philip

[R_J]

If you can unsolder pin 6 of LP801s then you can isolate the bridge rectifier from the mosfet circuit.

[dick_barton]

I would suspect either one or both mosfets are shorted so I would take them out to check.

[motophil]

Originally Posted by dick_barton

I would suspect either one or both mosfets are shorted so I would take them out to check.

And you were spot on. The rectifier is fine, the short across +- came from the mosfets across various components on the board. One of the mosfets is shot, 0 Ohm on DS.

It was all a bit a b*tch to desolder because there are rivets in some of the PCB holes.

So I have to replace the mosfets and will also replace the UP801S (FAN7530), since that quite often seems to be the cause for the mosfets to blow.

Now, what's a good source of components in europe? Mouser and Digikey both have the components but charge €20 for shipping to Germany. Nikko Electronics sells from the UK on ebay... anybody know if that's a trustworthy source?

- Philip

[petehall347]

Originally Posted by motophil

And you were spot on. The rectifier is fine, the short across +- came from the mosfets across various components on the board. One of the mosfets is shot, 0 Ohm on DS.

It was all a bit a b*tch to desolder because there are rivets in some of the PCB holes.

So I have to replace the mosfets and will also replace the UP801S (FAN7530), since that quite often seems to be the cause for the mosfets to blow.

Now, what's a good source of components in europe? Mouser and Digikey both have the components but charge €20 for shipping to Germany. Nikko Electronics sells from the UK on ebay... anybody know if that's a trustworthy source?

- Philip

RS components

[dick_barton]

I would imagine there are plenty of ebay suppliers since most commercial companies do have a minimum purchase cost before postage is free.
You could look at cpc.co.uk or Farnell and see if they have what you want and their delivery charges.

[ivtec]

https://www.shopjimmy.com/samsung-bn...t-repair-kit/\

[motophil]

OK, so I got the FAN7530 and the STF11NM60N off ebay from nikkoelec, an UK-based vendor to avoid the shipping times from China on the one hand and the shipping cost of vendors like mouser or digikey on the other hand.

They shipped TO-220 housing (with metal tab) instead of TO-220FP (isolated)
A good thing I could get hold of two heat condcutive TO-220 pads and fitting plastic screws to mount them. Now the TV's been running for 90mins without problems, smells or smoke.


Thanks everybody for the help,

- Philip

[onkeltom6]

Hallo Philip,

Wars das mit der Reparatur und läuft der TV noch immer ?
Stehe derzeit vor dem gleichen Problem. 6.3AT Sicherung ist durch und an den Mosfets und dem Gleichrichter messe ich einen Schluss...

Gruß
Thomas