SAE Mark 1b preamp repair

Hi all
I got SAE Mark 1B preamp thinking it will work. It powers up and I don't see any output working except scope out . Tape monitor is set to OUT. Unit is in very good cosmetic shape. Service manual days that if both channels don't work it most possibly be power supply issue. I want to get your sage advice and valuable input in fixing and restoring this wonderful unit
Thanks and regards
Baski

 

[N_Cook]

On 21/01/2014 18:48, gmbaskar@gmail.com wrote:

Hi all
I got SAE Mark 1B preamp thinking it will work. It powers up and I don't see any output working except scope out . Tape monitor is set to OUT. Unit is in very good cosmetic shape. Service manual days that if both channels don't work it most possibly be power supply issue. I want to get your sage advice and valuable input in fixing and restoring this wonderful unit
Thanks and regards
Baski

A bridging plug at power-amp-in required?

 

[David Farber]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:lbmj42$lps$1@dont-email.me...

On 21/01/2014 18:48, gmbaskar@gmail.com wrote:
Hi all
I got SAE Mark 1B preamp thinking it will work. It powers up and I
don't see any output working except scope out . Tape monitor is set to
OUT. Unit is in very good cosmetic shape. Service manual days that if
both channels don't work it most possibly be power supply issue. I want
to get your sage advice and valuable input in fixing and restoring this
wonderful unit
Thanks and regards
Baski


A bridging plug at power-amp-in required?

My schematic says that there is a 45 volt output from the emitter of Q17 in
the power supply. That feeds the left and right channel line level
amplifier. The emitter of Q10 and Q60 should show 45 volts. Then there is a
20 volts supply going to the eq filter board. The eq in/out switch is where
the 20 volts enters the circuit there. If you have signal at the scope
output, from there the signal goes to the discrete gain control, then to the
balance control, then to the amp, then to output jacks.

Q9-Q16 are the amp transistors for channel A. Q59-Q64 are the amp
transistors for channel B. Does the pc board show reference numbers?

Good luck.
--
David Farber
Los Osos, CA