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 10-10-2018, 12:04 PM   #1
angelos
Badcaps Veteran
 
Join Date: Dec 2012
City & State: Free State
My Country: South Africa
Line Voltage: 220V AC
I'm a: Professional Tech
Posts: 226
Default Protecting a horizontal output transistor

Howdy. I get in these CW62C chassis 29 inch LG crt tvs with blown line output transistors and normally all one does to repair them is to replace the 20nf 2kv cap but unfortunately all i can source cheap is fake spares that blow 2 seconds after switch on. The original is a 2SC6090LS but thats become obsolete so now we get supplied with a ST1510FX but these are fake too. I am now being forced to buy the original transistor from the agents at a very high cost. Is there a way i can protect the transistor on switch on? I have my handy 100x probe and would like to view the collector pulse on the transistor.

Your help on this will be greatly appreciated
angelos is offline   Reply With Quote
Old 10-10-2018, 02:16 PM   #2
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: 35,358
Default Re: Protecting a horizontal output transistor

The problem is that the fake device may have low breakdown Voltage that is not high enough to be used in the circuit as required. It is like trying to use 100V rating diode in place of the 1000V rating diode, nothing you can do to solve that.
__________________
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
budm is offline   Reply With Quote
Old 10-10-2018, 03:12 PM   #3
dick_barton
Badcaps Veteran
 
dick_barton's Avatar
 
Join Date: Aug 2015
City & State: Cardiff
My Country: Wales
Line Voltage: 230V AC, 50Hz
I'm a: Hobbyist Tech
Posts: 4,796
Default Re: Protecting a horizontal output transistor

I don't know if this would help you but it does give details on some high voltage LOP transistor.
https://www.westfloridacomponents.co...s/2sc4288a.pdf
__________________
Willing to help but I'm no expert.
dick_barton is offline   Reply With Quote
Old 10-10-2018, 04:18 PM   #4
jetadm123
Badcaps Veteran
 
Join Date: Feb 2010
City & State: California
Posts: 2,139
Default Re: Protecting a horizontal output transistor

My guess would be the fake devices are using a smaller die than the originals and cannot handle the higher current. Is the genuine transistor slightly heavier than the fake? You could also open them up and compare the two. Regardless, there's nothing you can do if the fake transistors don't measure up electrically to the original. Why don't you contact a reputable parts supplier and find out if they have a genuine in stock substitute for the original?

Last edited by jetadm123; 10-10-2018 at 04:20 PM..
jetadm123 is offline   Reply With Quote
Old 10-10-2018, 04:29 PM   #5
petehall347
Badcaps Veteran
 
Join Date: Jan 2015
City & State: worcester
My Country: United Kingdom
I'm a: Knowledge Seeker
Posts: 1,702
Default Re: Protecting a horizontal output transistor

https://uk.farnell.com/stmicroelectr...ngdom%2Fsearch
petehall347 is offline   Reply With Quote
Old 10-10-2018, 09:14 PM   #6
angelos
Badcaps Veteran
 
Join Date: Dec 2012
City & State: Free State
My Country: South Africa
Line Voltage: 220V AC
I'm a: Professional Tech
Posts: 226
Default Re: Protecting a horizontal output transistor

I send an email to ST Microelectronics asking who is their distributor in south africa but i got no response.
angelos is offline   Reply With Quote
Old 10-11-2018, 08:14 AM   #7
jetadm123
Badcaps Veteran
 
Join Date: Feb 2010
City & State: California
Posts: 2,139
Default Re: Protecting a horizontal output transistor

Maybe: Avnet South Africa. 202 Chelmsford, 2nd Floor, Essex Gardens Nelson Road, Westville Durban, South Africa Phone:+27 (0)31 266 8104.

Also try contacting Fairchild or International Rectifier.
jetadm123 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 - 2019
Powered by vBulletin ®
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 01:57 AM.
Did you find this forum helpful?