Introduction

The shutter electronics provides a negative fast rise pulse which "turns on" the pockels switch. The sequence of events which leads to the occurrence of the high voltage pulse begins with a pulse from the current rate coil. This pulse triggers a multivibrator in the delay generator, which, after a time determined by the delay adjust creates a delayed sync. Pulse. This delay sync. Pulse gates on a pulser which, in turn, causes the large thyratron to conduct.

The shutter electronics consists of a low voltage supply, a high voltage supply, a delay generator, a thyratron trigger, a filament, a reservoir supply and a thyratron tube. See the block diagram shown for the shutter electronics.

Equipment needed

Voltmeter
Oscilloscope (545, 564, 551 or 555)
Electrostatic voltmeter or 1000:1 probe
Signal generator

Controls

"Power" - on-off Switch S-401 supplies 115 VAC line voltage to the unit
"Test" - Momentary switch S-402 gives a continuity check to the current rate coil circuit.
It also starts the delay circuit which ultimately triggers the high voltage pulse to the pockels crystal.
"Voltage" - The knob controls the output of the high voltage supply.
:Delay" - Potentiometer R-406 provides a calibrated time delay between T zero and T out. T zero corresponds to the time of the current rate pulse and T out to the time of the thyratron trigger.
"Trigger" - The knob determines whether the thyratron can be triggered from the internal or external source. in case that "trigger" is in the external position, the delay circuit is disconnected from the thyratron and an external circuit providing an appropriate pulse at external trigger is required.
The rheostat R-402 located on the rear of the chassic controls the hydrogen pressure and thus the breakdown point.

General Check - System Disconnected

Check Fuse
Measure resistance from chassis to AC receptacle (min. 100 meg.).
Cycle power switch and repeat (b) (min. 100 meg.).
Set voltage adjustment fully CCW
Set trigger switch to external
install (KU27) thyratron tube
Measure resistance of tube grid to ground (min. 325 ohms).

To Check Low Voltage Supply

Connect system to 115 VAC line
Turn on system (check pilot lights)
Measure voltage on delay card

Terminal 6 (Pos DC volts) Min. 28 Max. 33
Terminal 2 (Pos DC volts) Min. 23 Max. 25

Measure Voltage on trig. Card

Terminal 9 (Pos DC volts) Min. 280 Max. 330

Measure Filament voltage at

Pin7 on KU27 tube or terminal 3 on trig. card. (AC volts) Min. 6.3 Max. 6.5

Adjust reservoir voltage from arm of R402 to ground Min. 5.2 Max. 5.5

To Check HV Supply

Turn system off; discharge HV supply
Connect electrostatic voltmeter (or 1000:1 probe if scope is used) to HV supply. Make sure voltage knob is fully CCW.
Turn system on and turn voltage knob CW slowly; do not exceed 8 KV. This should occur between Dot No. 4 and 6.
Turn knob fully counterclockwise and discharge HV supply. Turn system off.

To Calibrate Delay

Adjust digidial so dial reads 0.10 when delay pot is fully counterclockwise.
Turn dial to 1.00
Turn "trigger" to external
Remove test lamp from test button
Connect scope external sync. To"T" zero (positive)
Connect Channel 1 signal through 10:1 probe
Connect signal (set at 30-40 VDC 2-10 PPM) source to (J3) current rate connector in rear of shutter
Adjust Channel 1 display DC volts .5 V/cm @ 200 us/cm
Adjust calibration pot (R2 on delay card) so that pulse is 1.00 mses wide and shape is identical to fig. 1-A. (Min. .980 Max. 1.020 msec.)
Repeat above step for 2.00 msec. (Min. 1.968 Max. 2.040 msec.)
Connect channel 2 to T out 10. V/cm 200 usec/cm. (use 1:1 probe)
Set digidial to 1.00 msec.
Confirm that T out pulse looks similar to fig. 1-B
Disconnect signal source
Repeat Confirm step above using test button
Switch Trigger knob to internal
Repeat repeat step above. (Amplitude should be slightly lower).
Connect CH-2 to trigger card No. 10 or KU27 grid (use 10:1 probe)
Set CH-2 sensitivity at 10 V/cm
Sync. CH-2 to CH-1 time base X.2 (40 nsec./cm)
Push trigger button and observe waveform similar to fig. 1-C
Replace trigger button lamp.

Operation Test

Disconnect all test leads
With trigger in internal position, push trigger button - listen for "click".
Observe flash in KU27 tube.
Turn voltage knob clockwise to Dot No. 8. Confirm that there is no arcing.

WARNING: THIS VOLTAGE IS VERY HIGH 15-18 KILOVOLTS

If shutter passes test, fill in data sheet. Place data sheet with the shutter which should remain with the shutter until the shutter is shipped.

Shutter Electronics Block Diagram

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Waveforms

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( NOTE : THERE ARE ONE OR MORE PAGES MISSING HERE )

"Kilovolts" - Potentiometer R1 provides for selection of the firing voltage on the capacitor bank.
"Current Rate" (J5) provides a Sync. signal for the shutter electronics when the flash lamp fires.
"Remote Control" (J2) is a remote connector which makes it possible to operate the supply from a distance.
(J4) is a connector provided for connecting the flashlamp.
(J6) is a connector provided for connecting the capacitor bank.

Equipment Needed For Checkout

Voltmeter (Simpson 260 or equivalent).
Electrostatic Voltmeter.
400 uf 5 KV Capacitor.
Scope
DC hypot (0-5 KV)

Checkout of Logic Circuit

Install 1 amp fuse but remove 15 amp fuse
Place a jumper across Pin 1,2 on TB1
Connect line cord to supply and turn on AC power
When R(1) (Kilovolt potentiometer) is at its extreme counterclockwise position, the fire light should be on. Verify that fire light comes on.
Set the digidial to 2 KV. Verify fire light goes out and dump light comes on.
Depress charge button and verify that charge light comes on and dump light goes out. (dump solenoid should also lift but system will not charge.)

Checkout of Low Voltage Supply

Using the voltmeter measure 34 VDC ±10% across filter capacitor C1
Using voltmeter measure 25 V ±5% on the logic board at CR5 in respect to ground. Depress the charge button, then the dump button; this voltage should not change

Checkout of Trigger Circuit

Using the voltmeter measure 500 VDC to ground from the upper terminal of C4 or the amode of CR16
Turn the digidial to zero KV (the fire light should come on). Depress the fire button; listen for a ticking noise

Checkout of the HV Power Supply

Connect a negative DC hypot to J6
Set the digidial to 2 KV
Depress the charge button
Turn the hypot on and bring the voltage up slowly to 2 KV. Verify that the power supply fire light comes on when the hypot reaches approximately 2 KV. The meter on the power supply should read 2 KV also.

To Calibrate the HV Power Supply

Install the 15 amp fuse
Connect a 400 uf, 5 KV capacitor to J6
Turn the supply on
Set the digidial to 2 KV and depress the charge button. Verify that the system charges to approximately 2 KV and stops
Set the digidial to 4.5 KV and charge; if the supply does not stop at 4.5 KV, adjust R12 on the logic board
Set the digidial to 5.00 KV and verify that supply stops at 5.00 KV
Turn the supply off and connect the electrostatic voltmeter from ground to J6 (the solder connection of J6 do not remove the capacitor bank) and verify that the voltmeter on the supply agrees with the electrostatic voltmeter.

Checkout of the Sync. Signal

Connect a K1 flashlamp to J4
Connect an oscilloscope to J3; sync. int, time-base at .2 usec/cm and voltage sensitive on 10 V/cm
Charge supply to 3.5 KV
Fire system and verify a positive signal; if the signal is negative interchange the wires on L(1) (current rate coil).

When checkout is complete, turn supply off, disconnect capacitor and flash lamp, install cover and fill in checkout data sheet provided for K1 supplies. This data should remain with the supply until the supply is shipped.