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
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
BC142 can be substituted by BC141 available from Cricklewood Electronics.
Or you can get the BC142 from http://www.littlediode.com/components/search.php?mode=search&simple_search=Y&posted_data%5Bby_title%5D=Y&posted_data%5Bby_shortdescr%5D=Y&posted_data%5Bby_fulldescr%5D=Y&posted_data%5Bby_sku%5D=Y&posted_data%5Bincluding%5D=all&substring=BC142&search_redirect=Y
Or you can get the BC142 from http://www.littlediode.com/components/search.php?mode=search&simple_search=Y&posted_data%5Bby_title%5D=Y&posted_data%5Bby_shortdescr%5D=Y&posted_data%5Bby_fulldescr%5D=Y&posted_data%5Bby_sku%5D=Y&posted_data%5Bincluding%5D=all&substring=BC142&search_redirect=Y
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.
May be worth asking cricklewoodelectronics They often seem to be able to source unusual transistors.
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?
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?
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.
This will reduce operating temperature and may result in a more robust driver that does not burn 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.....
Littlediode aren't cheap but for one offs they are sometimes the last resort - other than E-Bay.
After some more testing and inspection it seams the out put transistors are blown and not he drive transistors. The originals are RCA16006 (2n3055). Am i best to replace it with the same 2n3055 or it there a drop in replacement that would be better. there are a few different versions of the 2n3055 and it looks like the main difference is the Maximum operating frequency (Ft) 2n3055(2.5MHz), 2n3055E (3MHz) or 2n3055H(0.8Mhz). I also Believe there is the option of using a TIP3055 which looks to have the same specs as the 2n3055E but this may require a circuit modification.
Thanks
Tom
Thanks
Tom
I think, it is the same model than the showed by post #80 about
http://www.diyaudio.com/forums/soli...odels-quasi-complementary-power-output-8.html
I would try the available versions from Magnatec, available by RS components:
Buy General Purpose Transistor PNP transistor,BC143 1A Magnatec BC143 online from RS for next day delivery.
Buy General Purpose Transistor NPN transistor,BC142 1A Ic 2Vce Magnatec BC142 online from RS for next day delivery.
For datasheet ask here:
sales@semelab-tt.com
If you observe unwanted oscillation effects, check C3 and C37 for compensation.
I miss the miller capacitor between C and B of the BC117 (T7). Maybe present and only a missprint in the schematic.
Today's 2N3055 are not suited to replace vintage versions. Use therefore the MJ21194 - go to
http://www.onsemi.com/pub_link/Collateral/MJ21193-D.PDF
check also this thread:
http://www.diyaudio.com/forums/solid-state/189161-2n3055-amp-claims-200-220-watt.html
Last edited:
after a while I did find some new old stock RCA-2n3055H. From my research the H is the correct for this application. It has the same frequency transition (ft) as the 2n5056 also noted in the circuit diagram. It does seam little slow 0.8MHz compared to most modern transistors like the MJ21193. I am little confused as to what the H stands for some say high power some don't say anything and just note it as 0.8MHz.
If i was to go with say the MJ21193 would i need to do any modifications? I read that when these faster transistors are used in vintage equipment some people have put a 20pf capacitor between base and emitter to reduce oscillations.
Thanks
If i was to go with say the MJ21193 would i need to do any modifications? I read that when these faster transistors are used in vintage equipment some people have put a 20pf capacitor between base and emitter to reduce oscillations.
Thanks
Anywhere in the first or the last URL from my previous post you will find that information.
Check out also this thread:
http://www.diyaudio.com/forums/parts/167680-vintage-transistors.html
so as post #20/21 about
http://www.diyaudio.com/forums/solid-state/48383-citation-12-substitute-transistors-2.html
Last edited:
The 2N3055E and 2N3055H are very different. The H is the more difficult one to obtain, the common one is the E variant. I believe that the TIP3055 is modelled on the E variant.
- Status
- Not open for further replies.