211: Difference between revisions

Triggering is done using  U65 [[155-0048-01]], which contains a horizontal amplifier (for external), trigger, and sweep generator.

The output of U65 drives the second section of dual output amplifier IC  U25 [[155-0057-00]] whose output is fed to the H-plates via output transistors  Q119/Q122.

U65 is mounted on the input board. The Unblanking signal from U65 is driven to CRT via Q134

Tek 211 can be operated from line power or the internal Ni-Cd battery. Line power is also used for charging the batteries. Internally the unit uses a DC-DC converter to generate the required voltages from the battery or line, using Q242, 2459, and T250. DC-DC converter generates the +5.6V, -5.6V, and +65V used in the unit. -1kV for CRT is generated using a voltage multiplier.

Instead of the transformer, a capacitive divider is used to step-down down the line voltage. C210 is the capacitor for providing charging voltage and C212 gets parallel to C210 for line operation. The value of these capacitors needs to be adjusted based on operating line frequency and voltage. Manual suggests recommended values of these capacitors for common line frequency and voltages. Input AC must be sinusoidal to offer the correct reactance to step-down the line voltage.