Pulled the preamplifier board, isolated from rest of the unit so I can work on it.
Electrolytic capacitors on small pre-boards all replaced, transistors are original.
Signal comes-out clean and output of NA06898-1 (A & B) once it reaches the next stage there is a weird oscillation (see picture) the sinewave seems to be shaking and duplicated on scope. Positive & Negative rails are good without ripple.
Electrolytic capacitors on small pre-boards all replaced, transistors are original.
Signal comes-out clean and output of NA06898-1 (A & B) once it reaches the next stage there is a weird oscillation (see picture) the sinewave seems to be shaking and duplicated on scope. Positive & Negative rails are good without ripple.
Attachments
Try a very much slower timebase setting - there may be a low-frequency modulation to show that effect.