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Lab Series L-5

2/17/2004 11:57 PM
Kyle Crison
Lab Series L-5
I've been working on an lab l5 and i have misplaced one of the RCA 7909 transistor and i was wondering if anyone could help me replace it, is there any alterative? thank you any help would be great
2/18/2004 12:14 AM

7909 sounds like a date code. I could not find any number like that in the drawings. Where is it in the circuit. The output xstrs were RCA40410.
2/18/2004 6:33 PM
Albert Kreuzer

could be a negative 9V regulator in a TO-220 case. AFAIK they're out of production, but you could make something up with a LM337.  
2/19/2004 6:56 AM

Possibly, but I don't recall a -9V supply inthere.
2/20/2004 9:07 PM
Albert Kreuzer

You're right, Enzo, it was just a quick shot when I saw the number. In fact they used +/-15V for the preamp with zeners for stabilizing.  
So it's probably just a "house" number for a power transistor - can't find the L5 power amp schematic, seems I just repaired the reverb driver and power supply (made up my own schematics, more than 20 years ago). FWIW, the L3 uses TIP29 and TIP30 power transistors, as does the reverb driver of the L5. As far as I can see, there are no special parts involved anywhere, so any generic transistor of roughly the same power rating should do. Just find out if it is a npn or pnp...  
BTW, just re-read the first post, there is no mentioning of the size - maybe its a small signal transistor? Then substituting would be even easier.  
The only non-bipolar three-legged thing in there was a PF5102 JFET in the input stage. Everything else generic npn or pnp.  
2/21/2004 1:58 AM
W Begg

Check your E-mail. I'm sending you a schematic and board layout in JPEG format. Hope this helps. worked on one last year.  
2/22/2004 4:41 PM

one question: would u sell a Lab L-5?  
i've got one at home (it does not work properly, but i could fix that), and beside its great clean tone it does nothing i find useful.  
how much could i charge for this beast?  

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