Tektronix 502 series, Instruction Manual

Page: 49 / 114

Troubleshooting the H o rizo n ta l A m p lifie r
For no trace or spot
If both beams are visible when the horizontal
deflection plates are externally shorted together,
but disappear when the short is removed, the
horizontal amplifier is in a state of unbalance.
The procedure for troubleshooting the Horizontal
Amplifier is somewhat the same as that ex­
plained previously for troubleshooting the Verti­
cal Amplifiers for unbalance.
Corresponding
points on opposite sides of the Horizontal Am­
plifier circuit should be progressively shorted
together until a point is reached where the
beams do not return to the face of the crt. The
stage immediately following this point is the one
which is defective. Check for open resistors in
the cathode and plate circuits.
For
insufficient
or no horizontal deflection
If the gain of the Horizontal Amplifier de­
creases, the trace will not extend to the left and
right sides of the crt screen. In addition, the
sweep timing will no longer be calibrated on
any range of the TIME/CM switch. If the change
in sweep timing and sweep length is slight, it
may be possible to correct this trouble by ad­
justing the high voltage and the XT CAL and
X20 CAL controls according to the instructions
contained in the Recalibration Procedure.
If the decrease in gain of the Horizontal Am-
lifier is more pronounced, or if there is no sweep
at all, check for components which will affect
the gain but not the balance of the amplifier.
The input cathode follower, V183B, should be
checked as one of the first steps. Also, the com­
mon resistances in the cathodes of the difference
amplifier stages should be checked.
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MAINTENANCE — TYPE 502
5-13