Help finding transistors, ic's

[jerry]

MAN ALIVE!! I AM HAPPY TONIGHT!!!  I was able to revive the
power section of my Beta Lead!!!  (See 6/6/00 post re: "Fried Beta Lead").
I had fried quite a few transistors...

Anyway, my preamp is still dead.  I am desperately seeking replacement
transistors for Q101 & Q102 (my schematic is illegible and the actual part
reads NP107a, which I can't find in any cross reference.)  I am also looking
for a replacement for IC106 (Dual And/Or inverter gate) which reads MC14506 on the
part and schematic, but which I can't find a supplier for.  Finally, there is
IC105 which is a 7404.  Can I use any 7400 series hex inverter to replace this?

If anyone can help I would _greatly_ appreciate it!!!  I'm so desperate to play through
my beautiful Sunn again...

Thanks,

Jerry
jjai@uclink4.berkeley.edu

BTW:  anyone in the SF Bay Area with amp repair issues should check out Hal
Petcher in SF @ Guitronics (415-621-3135).  I couldn't afford his services,
but he was willing to help me with advice anyway.  He's an authorized Fender/
Marshall guy and I couldn't come as far as I have with this Beta Lead if he hadn't
helped me.

[Joe]

: MAN ALIVE!! I AM HAPPY TONIGHT!!!  I was able to revive the
: power section of my Beta Lead!!!  (See 6/6/00 post re: "Fried Beta Lead").
: I had fried quite a few transistors...

: Anyway, my preamp is still dead.  I am desperately seeking replacement
: transistors for Q101 & Q102 (my schematic is illegible and the actual part
: reads NP107a, which I can't find in any cross reference.)  I am also looking
: for a replacement for IC106 (Dual And/Or inverter gate) which reads MC14506 on the
: part and schematic, but which I can't find a supplier for.  Finally, there is
: IC105 which is a 7404.  Can I use any 7400 series hex inverter to replace this?

Hey Congrats Jerry!!!  Love it when an amp comes alive again!

Your preamp schematic must be in worse shape than mine.  Q101 and Q102 are BC107 - they are just drivers for the LED indicators and shouldn't be that critical... soundwise anyway.

I couldn't find a crossreference for IC106 either, at least not with NTE.  

BUT IC105 crossreferences with the SUNN part number (22-7404) to an NTE74C04, and not to the standard 7404 (NTE7404) version.  I'm certainly not up to speed on my chips... but the standard 7404 would be TTL and not CMOS... the Beta does use the CMOS version.  With similar specs for voltage and pinouts, maybe any hex inverter would work, but it would certainly affect the sound... and probably not in a good way.

[jerry]

Joe,

Thanks a lot!!  I was able to find a BC107 and a 74C04 without
much trouble!!  AMAZING!  I'll probably be able to give it a try this
weekend (which is coming up fast!).

The only thing I'm afraid of now is that IC106 is out...  It seems to have
a little leakage (I've been testing IC's by checking the voltage at each pin
and I'm showing .5V at a few pins that should read OL...) but maybe it still
works?  My fingers are tightly crossed!!!

Thanks for your help Joe!  (Do you own a Beta Lead as well?)  And if you
(or anyone finds a replacement for IC106, I'd love to know!  Thanks again!!!!

I'll let everyone know if I get my amp working again!

[Kevin at VMR]

The cross reference for BC107 is 123A (ECG), and I think NTE is 123.  The original part for IC106 is MC14506 (BCP C-MOS).  ECG shows a cross reference for MC14506B to ECG 4506B (IC C-MOS DUAL EXPANDABLE AND/OR INVERT GATE).  Since that is the function of the original IC106 I would say it's a safe bet that the ECG part is a direct replacement.  Good Luck!