Teledyne M5000B operating instructions Battery-Powered Oscilloscope Synchronization Point

Part II: Maintenance/Analysis Unit Maintenance 5

5.5.8 Integrated Reference and Measuring Signals

You can observe the reference and measuring signal at the first stage of integration by connecting the scope probe to TP6 (reference signal) and TP7 (measuring signal) at the detector unit. A dual trace scope is advantageous but not required for this observation.

The test points’ significance is that they reveal proper switch action. The display shows a sawtooth pattern that is a charge-discharge of the first capacitor in the integrating network. This ripple is the AC component of the reference and measuring signal after the pulses are converted to DC. The sawtooth patterns must be displayed 180° with respect to each other as viewed with a dual trace scope. They must both be present.

If one is missing, the switch is not switching. If the sawtooth shows a broken pattern, the switching action is feeble or irregular. Usually, you can fix the faulty condition of the switch by slightly changing the switch position.

The action of a bar magnet and a rotating chopper disc activate themagnetic mercury reed switch. An aluminum motor mounting block houses a bar magnet. This bar magnet is parallel with the mercury chopper switch.

The chopper disc is a green and black disc mounted on the filter wheel shaft next to the motor. The disc is composed of both magnetic and non- magnetic materials. As the shaft rotates, the magnetic portion of the disc shorts themagneticfluxasitpassesbetweenthemagnetandtheswitch. Thenon-magnetic portion of the disc enables flux lines from the bar magnet to activate the mercury switch.

5.5.9Battery-Powered Oscilloscope Synchronization Point

Because the line frequency cannot synchronize battery-powered oscillo- scopes, use TP8 at the detector module to provide external synchronization.

5.6Interface Board Terminals Strip

At the bottom of the interface PCB on the Control Unit, are three terminal strip where wiring is distributed to other sections of the Model 6000B System. Such as AC power for the D2 lamp power supply, DC Power to the preampli- fier, High DC voltage for the photodetector, and signals to control calibration solenoids and filters. To gain access to this terminals, the silkscreen cover must be removed. These terminals are wired in the factory.

Teledyne Analytical Instruments

Part II: 5-7