Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting TVs and Video Sources
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 04-27-2019, 09:28 AM   #1
Kairi
Member
 
Join Date: Nov 2013
City & State: London
My Country: United Kingdom
Line Voltage: 240VAC 50Hz
I'm a: Hobbyist Tech
Posts: 42
Default Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Hi guys,

So I was messing with the power board to my Samsung LE40C750R2K TV whilst I was waiting for the main board to arrive and in hindsight was probably a stupid idea but I hadn't anticipated for what actually happened.

I had the power board connected the the inverter board only and switched on the TV. The backlight came on. I then unplugged the the cable connecting the power board to the inverter board (CNI801) and as soon as I did this, the blue capacitor (CI826) next to the connector starting sparking and smoke came out from it, and was especially violent at the solder point. This capacitor connects directly to ground so I guess as soon as the load was removed, the electricity could only flow through the capacitor and blowing it in the process. The cap does have a marking of 82J and 6KV which I assume can withstand 6000v

Does anybody who is more electronically savvy than me knows what may have happened here? I have plugged in power boards into the mains without anything connected in the past but nothing has happened. My logic would assume that if I unplugged the inverter board, the screen just wouldn't light up, it shouldn't blow a capacitor rated for 6kv.

I can replace this capacitor without problem but I just want to know if there's a chance that by unplugging the inverter cable, something else could have fried on the board.

The power board is BN44-00341A

Thanks
Attached Images
File Type: jpg 872067884.jpg (217.5 KB, 23 views)
File Type: jpg 771811000.jpg (272.6 KB, 15 views)
File Type: jpg 932635901.jpg (242.8 KB, 30 views)
File Type: jpg 699918507.jpg (169.2 KB, 19 views)

Last edited by Kairi; 04-27-2019 at 09:32 AM..
Kairi is offline   Reply With Quote
Old 04-27-2019, 10:01 AM   #2
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 7,990
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Unpluging the load with power on caused a spike that could have been 10-20kv or more, likely the cap is the only problem, you will find out after you replace it if the rest of the circuit still works.
R_J is offline   Reply With Quote
Old 04-27-2019, 10:09 AM   #3
tvtimmy
Badcaps Veteran
 
tvtimmy's Avatar
 
Join Date: Mar 2015
City & State: milwaukee,wi
My Country: usa
Line Voltage: 120VAC/60HZ
I'm a: Knowledge Seeker
Posts: 1,097
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

You should be ok with just replacing the capacitor.
tvtimmy is offline   Reply With Quote
Old 04-27-2019, 01:23 PM   #4
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,206
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

So you disconnect the cable on CNI801 while the backlights are on?
You have Power supply/inverter board combo., that HV connector CNI801 goes to the Balancer board.
__________________
Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809

Last edited by budm; 04-27-2019 at 01:26 PM..
budm is offline   Reply With Quote
Old 04-27-2019, 02:39 PM   #5
Kairi
Member
 
Join Date: Nov 2013
City & State: London
My Country: United Kingdom
Line Voltage: 240VAC 50Hz
I'm a: Hobbyist Tech
Posts: 42
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Quote:
Originally Posted by budm View Post
So you disconnect the cable on CNI801 while the backlights are on?
You have Power supply/inverter board combo., that HV connector CNI801 goes to the Balancer board.
Yes that's precisely what I did. The board that CNI801 connects to has a lot of mini transformer in the same style as the 2 big ones on the power board. This may very well be the balancer board you're talking about, I'm not 100% certain of the terminology but it powers the backlight.

What I'm intrigued about is why the surge happened only when I unplugged it whilst it was on, but nothing happened when I powered the PSU alone to check for voltages.

Last edited by Kairi; 04-27-2019 at 02:41 PM..
Kairi is offline   Reply With Quote
Old 04-27-2019, 02:44 PM   #6
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,206
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

The arcing Voltage can be really high.
budm is offline   Reply With Quote
Old 04-27-2019, 07:00 PM   #7
Kairi
Member
 
Join Date: Nov 2013
City & State: London
My Country: United Kingdom
Line Voltage: 240VAC 50Hz
I'm a: Hobbyist Tech
Posts: 42
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

I replaced the capacitor and the power board appears to be fine. The backlight still works but I'm sure as hell I won't be disconnecting any leads with the power on anymore.

Interestingly, I checked the capacitor with a components tester and it was reading fine. A quick check with a multimeter also shows that there's no shorts in it.
Kairi is offline   Reply With Quote
Old 04-27-2019, 07:57 PM   #8
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,206
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Never good idea to disconnect while TV is ON, especially the High Voltage, You are lucky you did not get shock from that connector (>3000V).
budm is offline   Reply With Quote
Old 04-27-2019, 08:58 PM   #9
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 7,990
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

It could be that the cap. arced internally but did not short or effect it's capacity, but it could arc and short out even with a couple thousand volts across it now.

Last edited by R_J; 04-27-2019 at 09:06 PM..
R_J is offline   Reply With Quote
Old 04-27-2019, 09:33 PM   #10
sean0118
Member
 
Join Date: Jun 2016
City & State: Sydney NSW
My Country: Australia
Line Voltage: 230VAC
I'm a: Knowledge Seeker
Posts: 76
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

The output of the power supply probably has high inductance, once you remove the load the current through the inductor will continue to flow causing the voltage to rise sharply.

Some power supplies, like flybacks in CRT TVs use this to generate very high voltages.

But in your case the voltage got high enough that it found a path through that capacitor.
sean0118 is offline   Reply With Quote
Old 04-28-2019, 04:54 AM   #11
Kairi
Member
 
Join Date: Nov 2013
City & State: London
My Country: United Kingdom
Line Voltage: 240VAC 50Hz
I'm a: Hobbyist Tech
Posts: 42
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Thanks for the explanation and bring to me the awareness of the dangers messing with the inverter. Luckily I didn't get a shock and have dodged a bullet this time.

PS board, inverter and the main board that arrived this morning, works fine. I've not plugged it into the T-con yet, and I'll make another thread about that in regards to possible risks of plugging this on since this TV has an unknown history.
Kairi is offline   Reply With Quote
Old 04-28-2019, 09:52 AM   #12
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 7,990
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

On the secondary of the inverter transformer you would'nt have received much of a shock, but the high voltage at high frequency arc will burn you, and it will hurt.
R_J is offline   Reply With Quote
Old 04-28-2019, 03:49 PM   #13
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,206
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

https://assets.shopjimmy.com/media/c...341a-top_1.jpg
It is rated at 1000V 180mA as printed on the board, the firing is proBably about 3000V. I think it will hut quite a bit.
budm is offline   Reply With Quote
Old 04-29-2019, 12:52 PM   #14
nomoresonys
Badcaps Veteran
 
Join Date: Jan 2013
City & State: midwest
My Country: U.S.
I'm a: Knowledge Seeker
Posts: 7,702
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

That would probably hut LIKE HELL.
nomoresonys is offline   Reply With Quote
Old 01-15-2022, 10:28 AM   #15
Jimmy1979
Member
 
Join Date: Apr 2015
City & State: Eindhoven
My Country: holland
I'm a: Knowledge Seeker
Posts: 88
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Quote:
Originally Posted by Kairi View Post
Hi guys,

So I was messing with the power board to my Samsung LE40C750R2K TV whilst I was waiting for the main board to arrive and in hindsight was probably a stupid idea but I hadn't anticipated for what actually happened.

I had the power board connected the the inverter board only and switched on the TV. The backlight came on. I then unplugged the the cable connecting the power board to the inverter board (CNI801) and as soon as I did this, the blue capacitor (CI826) next to the connector starting sparking and smoke came out from it, and was especially violent at the solder point. This capacitor connects directly to ground so I guess as soon as the load was removed, the electricity could only flow through the capacitor and blowing it in the process. The cap does have a marking of 82J and 6KV which I assume can withstand 6000v

Does anybody who is more electronically savvy than me knows what may have happened here? I have plugged in power boards into the mains without anything connected in the past but nothing has happened. My logic would assume that if I unplugged the inverter board, the screen just wouldn't light up, it shouldn't blow a capacitor rated for 6kv.

I can replace this capacitor without problem but I just want to know if there's a chance that by unplugging the inverter cable, something else could have fried on the board.

The power board is BN44-00341A

Thanks
Hello

What was the value of the capacitor?
I have the same problem.
Was is 82j 6kv
Or B2j 6kv?
Thanx
Jimmy1979 is offline   Reply With Quote
Old 01-15-2022, 10:55 AM   #16
lotas
Badcaps Veteran
 
Join Date: Jan 2016
City & State: Sochi
My Country: russia
I'm a: Knowledge Seeker
Posts: 743
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Quote:
Originally Posted by Jimmy1979 View Post
Hello

What was the value of the capacitor?
I have the same problem.
Was is 82j 6kv
Or B2j 6kv?
Thanx
Most likely 82pF 6kV.
lotas is online now   Reply With Quote
Old 01-15-2022, 11:09 AM   #17
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,370
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

6kv 47pf
https://elektrotanya.com/samsung_bn4...wnload.html#dl
vinceroger69 is offline   Reply With Quote
Old 01-15-2022, 11:36 AM   #18
Jimmy1979
Member
 
Join Date: Apr 2015
City & State: Eindhoven
My Country: holland
I'm a: Knowledge Seeker
Posts: 88
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Quote:
Originally Posted by vinceroger69 View Post


I found that service manual too but I donít know if itís the same.
I have a Bn44-00341a

The number on manual is not same.
Attached Images
File Type: jpg DECB06D8-6BC8-4141-A9EB-B023FFCFB0E2.jpg (111.6 KB, 6 views)
Jimmy1979 is offline   Reply With Quote
Old 01-15-2022, 11:39 AM   #19
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,370
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Quote:
Originally Posted by Jimmy1979 View Post
I found that service manual too but I don’t know if it’s the same.
I have a Bn44-00341a

The number on manual is not same.
no its a b revision service manual, but should be the same cap in my opinion, its in the exact same position next to the connector with the same board location number its the only 6kv cap on the schematic so makes sense too

Last edited by vinceroger69; 01-15-2022 at 11:43 AM..
vinceroger69 is offline   Reply With Quote
Old 01-15-2022, 12:09 PM   #20
Jimmy1979
Member
 
Join Date: Apr 2015
City & State: Eindhoven
My Country: holland
I'm a: Knowledge Seeker
Posts: 88
Default Re: Samsung LE40C750R2K capacitor on PSU blew up when unplugging inverter board

Quote:
Originally Posted by vinceroger69 View Post
no its a b revision service manual, but should be the same cap in my opinion, its in the exact same position next to the connector with the same board location number its the only 6kv cap on the schematic so makes sense too
I will order one 47pf 6kv and test it out.
If it goes Lucy in the sky then i know itís not good or other problem.
Thank you for your help👍🏻
Jimmy1979 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums © 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 04:28 PM.
Did you find this forum helpful?