Edgetech 2000-CSS, User Manual

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4. GAIN A and B test points show the positive-going TVG ramp voltage for the low and high frequency
sonar channels.
5. Four test points monitor the TVG’d analog sonar data. They are:
ADC 0 Port SSL ADC2 Stbd SSL
ADC 1 Port SSH ADC3 Stbd SSL
These test points are useful when doing a rub test.
6.3.7.5 DDC Test points
This board does not have any test points. LEDs monitors display the channels on the card that are running.
Side A and Side B. In a normally operating vehicle with both channels collecting data the lights will
alternate.
6.3.7.6 Modem Board Test Points
FSK. Monitors the 3200 kHz to 2800 kHz frequency-shift-keyed signal from the topside unit. This signal
is used for optional commands. May not be present in all systems.
Trig. A TTL signal that synchronizes the topside and sub-sea units with other topside equipment.
Follows the SYNC signal input on the topside unit. It is not used in all system configurations.
6.3.7.7 Other Checks
Periodically check the integrity of the sea ground capacitor attached to the rear bulkhead.
6.3.8 Tow Cables
Historically, most system problems occur in the tow cable and their connectors. Before proceeding, verify
cable continuity from the shipboard end of the cable to the towfish. The presence of a shorted or open
wire in a tow cable can be determined by using a multi-meter. An open or shorted wire can be located
using the techniques described in the following subsections.
6.3.8.1 Shorted Wire
The following procedure may be used to approximate the distance to a single short or a point of high
leakage between a conductor pair or from a conductor to a shield.
Disconnect both cable ends.
1. Short the two connector pins (or wires if un-terminated) of the shorted pair at both ends and
measure the total resistance between the ends.