Moderators: Dave Moll, Andrew Davie, Steve Anderson
Steve Anderson wrote:Harry, how are you triggering the horizontal oscillator? Are you using the suggested BRY39? I assume you were not able to get the 1.3V VDR?
It looks like severe non-linearity in the horizontal oscillator and/or the output stage. The AD series of transistors were also germanium not silicon.
Steve A.
Klaas Robers wrote:And is the scanning not scanning up? From the bottom to the top? In most cases the lines are wide in the beginning of the scan and close at the end of the scan. This is then because the input saw tooth is not a linear sawtooth but a exponential saw tooth.
Look first at the wave form on the point where "1.7 volt" is indicated. The saw tooth there should be very linear. If not: as always, rubbish in - rubbish out.
Klaas Robers wrote:Very good! But at the base of the 2N3904 I see that the frame sawtooth is still not ramping straight. This might be because of the type electrolytic capacitor of 200 uF. This should be a tantalium capacitor. The aluminium capacitors when discharged, they still keep some of their charge, which returns just after the discharge. That gives a bended sawtooth.
Klaas Robers wrote:In any way, see first that the sawtooth at the base of the 2N3904 is linear, not bended. Also look at the sawtooth form at the emitter of this transistor. This should have the SAME FORM. If that is correct, don't suspect the amplifier right of the 2N3904.
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