Author Topic: LF Capacitors  (Read 423 times)

Offline Tom

  • Trader
  • Trade Count: (+63)
  • *****
  • Posts: 1,744
LF Capacitors
« on: September 12, 2018, 06:01:59 PM »
I have a dead Samsung LCD 32" screen
It powers on but no picture, seems a common problem on these and was told the capacitors needs replacing?

Looking at trying some diy and replace the 6 caps on the power supply board and I am looking for the following capacitors, possibly some guidance and recommendations and soldering iron... as I am a total newbie at these.

2 x 500V 100uf
1 x 10V 2200uf
1 x 25V 560uf
1 x 250V 47uf
1 x 250V 22uf

Perhaps someone has a complete replacement board to swop/ sell.

Just putting it out there :)

Kindest regards
Tom
Digital Media Conversions - Preserving Memories

Offline Razr

  • Trade Count: (+4)
  • AVForums Veteran
  • ***
  • Posts: 170
Re: LF Capacitors
« Reply #1 on: September 12, 2018, 07:19:01 PM »
Would you need to replace them all . if you have a multimeter i think you can test them for continuity  , maybe someone can help if im correct?

try places like communica or mantech or something thats near you for the caps

i say get a cheap soldering iron because its going to be a one time fix and its a 32inch tv so spending big bucks is pointless , i know builders has cheapies

and rosin core solder builders also sells small pieces , but the place you get the caps will also sell

Offline Tom

  • Trader
  • Trade Count: (+63)
  • *****
  • Posts: 1,744
Re: LF Capacitors
« Reply #2 on: September 12, 2018, 08:41:38 PM »
Thank you so much Razr. I think I have heard of Mantech before.

Shocking... NOW I found out the hard way not to touch the capacitors after unplugging.... lmao

Newbie question. Can one fit "better" caps?
Digital Media Conversions - Preserving Memories

Offline JANNAS

  • Trade Count: (0)
  • AVForums Super Veteran
  • ****
  • Posts: 550
Re: LF Capacitors
« Reply #3 on: September 12, 2018, 09:29:50 PM »
You have to discharge the high voltage caps and desolder them before testing. That SMPS can kill, better take that to someone who knows this stuff ! :o

Offline Tom

  • Trader
  • Trade Count: (+63)
  • *****
  • Posts: 1,744
Re: LF Capacitors
« Reply #4 on: September 12, 2018, 10:28:43 PM »
If killed in the quest to learn something new then it wont be in vain. *said tongue in cheek
In all honesty I know these things can bite.

Next question, how does one discharge caps effectively or do I just leave the unit unplugged for a cpuple of hours before touching?
Digital Media Conversions - Preserving Memories

Offline GECO

  • Commercial Member
  • Trade Count: (+7)
  • *****
  • Posts: 7,923
Re: LF Capacitors
« Reply #5 on: September 13, 2018, 02:33:21 AM »
you can use a large 2-3k 10w resistor across the poles

Offline Tom

  • Trader
  • Trade Count: (+63)
  • *****
  • Posts: 1,744
Re: LF Capacitors
« Reply #6 on: September 13, 2018, 11:14:27 AM »
Thank you Rudi.

I ordered some Flux Capacitors last night.... From the future.  :dop:
Digital Media Conversions - Preserving Memories

Offline El Sid

  • Trade Count: (+11)
  • AVForums Grandmaster
  • *****
  • Posts: 1,129
Re: LF Capacitors
« Reply #7 on: September 13, 2018, 12:19:05 PM »
Tom I can help you with the soldering if you want - give me a shout when you have the caps. But there's no guarantee it's the caps causing the problem...

Mantech is close - Laub St off Eloff, south of the M2. RSE electronics is just around the corner from them.
« Last Edit: September 13, 2018, 12:24:20 PM by El Sid »

Offline Tom

  • Trader
  • Trade Count: (+63)
  • *****
  • Posts: 1,744
Re: LF Capacitors
« Reply #8 on: September 13, 2018, 02:38:16 PM »
Thank you so much for the info re electronics places and also the offer to solder for me El Sid

I just got my hands on a cheapie soldering iron, wire and solder sucker. Only things needed now are the caps and some plutonium.... :pleasant:
Digital Media Conversions - Preserving Memories

Offline ThomasH

  • Trade Count: (0)
  • AVForums Junior Member
  • *
  • Posts: 12
Re: LF Capacitors
« Reply #9 on: September 13, 2018, 07:15:11 PM »
Are any of the caps bulging?

Offline AudioEars

  • Trade Count: (+3)
  • AVForums Veteran
  • ***
  • Posts: 166
    • Vorna TV & Satellite
Re: LF Capacitors
« Reply #10 on: September 13, 2018, 08:06:16 PM »
Hi Tom
WhatsApp me the model of TV and part number of the PCB Samsung start with BN44..... and I will look and see what I can find  for you
On the 500V caps I use a 100w globe to discharge as one can see the globe light up for a brief moment and you know the energy has in the cap' has discharged
Rudi's way is also a great way to discharge caps
Chat soon
Kind regards
Andrew

Offline ALF

  • Trade Count: (+1)
  • AVForums Veteran
  • ***
  • Posts: 493
Re: LF Capacitors
« Reply #11 on: September 14, 2018, 06:56:26 AM »
I will replace the low voltage caps first after the transformer and must be low ESR tipe, then if it is a tube backlight and still now dispkay after caps then 90% that one of the tubes or inverter board is dead then scrap.
Then there is always a small value high voltage cap on primary side very close to a heatsink replace that also useily dries out due to heat
"the fostex thang".....

Offline Tom

  • Trader
  • Trade Count: (+63)
  • *****
  • Posts: 1,744
Re: LF Capacitors
« Reply #12 on: September 14, 2018, 04:31:56 PM »
Ah wow, thank you for replies guys. Really appreciate it

No visible bulging of the caps

There is some discoloration of the board around the low voltage caps indicating higher heat very prominent around the heatsink.

I had this before on a smaller samsung pc screen and my techie who is now in Italy replaced the caps on it and it is still working today. Thinking this is the same issue and seems a common problem.

The tv model is Samsung UA32F5000R
Part number of power supply board is BN4400... getting my magnifying glass..goodness me, I should have eaten more carrots as a kid...BN4400606BSE38D4FR130
The carrot reference... anyone ever seen a rabbit wearing glasses? Giggle...
I thank you for your patience with me as I dont want to turf this tv.
Kindest
Tom
Digital Media Conversions - Preserving Memories

Offline BobsYourUncle

  • Trader
  • Trade Count: (+31)
  • *****
  • Posts: 1,368
Re: LF Capacitors
« Reply #13 on: September 26, 2018, 10:39:39 PM »
I had a Samsung 22 inch PC screen that needed the 2 820uf( or similar , was not a common value) caps replaced if I recall correctly. That solved the issue and it worked well.
Kempton Park, Estrand,GP