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 12-27-2018, 12:04 PM   #21
tom66
EVs Rule
 
tom66's Avatar
 
Join Date: Apr 2011
City & State: Leeds
My Country: UK
Line Voltage: 230Vac 50Hz
I'm a: Professional Tech
Posts: 32,373
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

Good fix, thanks for the update.
tom66 is offline   Reply With Quote
Old 06-20-2019, 11:50 AM   #22
Pat P.
New Member
 
Join Date: Mar 2019
City & State: Kitchener, Ontario
My Country: Canada
I'm a: Knowledge Seeker
Posts: 5
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

I'm chasing somewhat of the same issue. Started with a shorted cap at c204 between Vcc and gnd of Ic201 (200d6). replaced with a 50uf (original was 100) to check and everything worked for about 10min.
replaced Ic201 based on OP's xperiences as everything else seemed to test fine, as well as replacing C204 with the proper value.
Blew out the 2.0 ohm resistor and the driver FET Q202.
replaced those and IC201 again(as a precaution), and got fluctuating voltages on the high voltage pin of IC201 .
IC201 was showing high frequency bursts on the gate of the FET, and as I was continuing to probe it blew out the 2.0 ohm resistor and the FET again.
I've checked all around that area and components seem fine.
Any advice?
Pat P. is offline   Reply With Quote
Old 06-20-2019, 04:32 PM   #23
Beau28713
Member
 
Join Date: Feb 2018
City & State: Bryson City NC
My Country: United States
Line Voltage: 120Vac 60Hz
I'm a: Hobbyist Tech
Posts: 50
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

If i remember correctly I blew the same FET and resister once because I had the ic-201 removed from the circuit when I powered up the board. IF I remember correctly there is a small transformer located next to the IC-201, FET and resistor. Make sure incoming/outgoing voltage is good on that. make sure all connections and solder joints are good in the area also. A cold solder joint will cause some weird symptoms and have you chasing ghost.

Also remember there is a floating ground and a chassis ground on that board.
Beau28713 is offline   Reply With Quote
Old 06-21-2019, 05:25 AM   #24
Pat P.
New Member
 
Join Date: Mar 2019
City & State: Kitchener, Ontario
My Country: Canada
I'm a: Knowledge Seeker
Posts: 5
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

Thanks, I've given the board a good look over, but I'm sure my tired old eyes may have missed something.
I'll report back when I've had another go at it.
Pat P. is offline   Reply With Quote
Old 11-05-2019, 02:22 PM   #25
Pat P.
New Member
 
Join Date: Mar 2019
City & State: Kitchener, Ontario
My Country: Canada
I'm a: Knowledge Seeker
Posts: 5
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

Just gave up and bought a used y-sus for $45. back up and running!
Pat P. is offline   Reply With Quote
Old 11-07-2019, 08:01 AM   #26
Beau28713
Member
 
Join Date: Feb 2018
City & State: Bryson City NC
My Country: United States
Line Voltage: 120Vac 60Hz
I'm a: Hobbyist Tech
Posts: 50
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

Hey as long as it is working.
Beau28713 is offline   Reply With Quote
Old 03-20-2020, 02:56 PM   #27
alain28
New Member
 
Join Date: Feb 2018
City & State: Bailleau-Armenonville
My Country: France
I'm a: Knowledge Seeker
Posts: 3
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

I am looking for C417 and C418 value. Does the rated value is 500v ?
Thank you.
alain28 is offline   Reply With Quote
Old 03-22-2020, 02:52 PM   #28
Beau28713
Member
 
Join Date: Feb 2018
City & State: Bryson City NC
My Country: United States
Line Voltage: 120Vac 60Hz
I'm a: Hobbyist Tech
Posts: 50
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

Quote:
Originally Posted by alain28 View Post
I am looking for C417 and C418 value. Does the rated value is 500v ?
Thank you.

I no longer have this tv, but ill look around in my notes and pictures and see what i can find for you.
Beau28713 is offline   Reply With Quote
Old 03-22-2020, 08:18 PM   #29
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 8,082
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

I believe they are 0.022F
R_J is offline   Reply With Quote
Old 03-24-2020, 03:13 AM   #30
alain28
New Member
 
Join Date: Feb 2018
City & State: Bailleau-Armenonville
My Country: France
I'm a: Knowledge Seeker
Posts: 3
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

Thank you very much for the answers of Beau28713 & R_J
You can see a picture of these caps here:
http://www.coppelltvrepair.com/p/154...-image-problem

On the left and right they are C416/415 & C401/402 that seems similar to the couple C417/418.
The dielectric is light grey then the value could be low but also different because the height is not the same.


It is not for me but a colleague so I Don't have the board.
alain28 is offline   Reply With Quote
Old 03-24-2020, 08:49 AM   #31
Beau28713
Member
 
Join Date: Feb 2018
City & State: Bryson City NC
My Country: United States
Line Voltage: 120Vac 60Hz
I'm a: Hobbyist Tech
Posts: 50
Default Re: LG 50PN4500 - fluctuating Vcc/18V supply on Y-sustain board causing fault

I do believe R_J is correct in saying they are .022uF and around 500v. The safest way to proceed would to just buy the repair kit. That way you will have the correct caps and plus you will have some spare parts in case you need them.
Beau28713 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 06:35 PM.
Did you find this forum helpful?