BC142/143 transistor replacement

[tomst]

Hi
I have a leak Stereo 30 plus and have just burned up a BC142 (T8 on the diagram) drive transistor due to a worn out trim pot. The mentioned transistors are getting quite difficult to find. Does anyone have any ides as to a good replacement for both. The output transistor on this amp is is the RCA16006 (same as 2n3055 i believe)
thanks
Tom

[AndrewT]

do you have data for the 142/143?

[tomst]

Sorry circuit diagram here

[tomst]

Does this help

[KatieandDad]

BC142 can be substituted by BC141 available from Cricklewood Electronics.

Or you can get the BC142 from http://www.littlediode.com/component...rch_redirect=Y

[AndrewT]

5W, 50Vce0, 1A, 12pF, 20MHz
Many To126 could do this job.
All To126 are ecb pin out.

[Spiny]

try ebay uk, there are a few of each about, seems the 143 is the difficult one, futurlec have the 142.

May be worth asking cricklewoodelectronics They often seem to be able to source unusual transistors.

[tomst]

Thanks for the replies.
The little Diode company has both the 142 and 143.
Should i just use these again or would it be better to use something different?

[AndrewT]

If you can get heatsinks for the top hat style case then buy the same.
This will reduce operating temperature and may result in a more robust driver that does not burn out.

[wahab]

Originally Posted by AndrewT

20MHz
Many To126 could do this job.
All To126 are ecb pin out.

Not all TO126 suit the purpose since Hfe is 5 typical at 20Mhz , that s about a 100Mhz Ft , so a replacement should be fast enough , BD139/140 pair will do it perfectly although the output pair is so slow that 20Mhz Ft devices should work flawlessly , but one never knows.....