Tektronix 1705A High VoltageOscillator Check, CRT VoltageCheck

Maintenance
1705A Spectrum Monitor 6-17
Connect the oscilloscope probeto the anode of CR5 and the probe ground to
TP1. The signal should be a clipped sine wave of+75 to +200 V p-p.
High VoltageOscillator Check
Connect the oscilloscopeprobe to T1 pin 3 (Q6 collector) and the probe ground
to TP1. Power up the supply. The signal should be a+60 V p-p, 22 kHz sine
wave.
Check the following voltagesusing the digital multimeter:
Table6 -6: High Voltage Os cillator Test Points
CircuitLocation Volta ge
T1, pin4 Approximately +40 V.
T1, pin13 Less than +2 V.
U2, pin 2 Approximately +4.8 V.
U2, pin 6 +4 to +11V.
CR9, cathode Approximately +100 V.
CRT VoltageCheck
NOTE. This check requiresa high voltage probe having an input resistance of 1
GΩor more.
Connect the high voltageprobe ground to TP1.
Load the Low VoltsSupply with the instrument, or with a 20Ω, 2 watt resistor
loading the 5 V supply.
Power up the Power Supply.
Use the high voltage probe to measurethe voltage at the anode of CR4. It
should be approximately --2530 V.
Measurethe voltage at the anode end of CR3. It should be 50--150V more
negative than the readingfrom the anode of CR4.