1. Test the woofer: Place one test lead securely on each of the RED test points on the Access
Card. A properly functioning woofer will read approximately 5.0 ohms DCR, ±0.5 ohm (See
Figure 3). A significantly higher reading indicates an open voice coil, meaning the woofer
must be replaced. A significantly lower reading indicates a voice coil that is shorting, mean-
ing the woofer must be replaced.
2. Test the compression driver: Place one test lead securely on each of the YELLOW test
points on the Access Card. A properly functioning compression driver will read approxi-
mately 4.3 ohms DCR, ±0.5 ohm (See Figure 4). A significantly higher reading indicates an
open voice coil, meaning the compression driver must be replaced. A significantly lower
reading indicates a voice coil that is shorting, meaning the compression driver must be re-
placed.
3. Test the PTP (Power Tracking Protection) network: Place one test lead securely on each of
the GREEN test points on the Access Card. A properly functioning PTP will read no more
than 2 ohms (See Figure 5). If the reading is higher, replace the SK-3 lamps on the cross-
over PCB.
4. Unplug the Access Card and re-install the switch card in exactly the same position it was in
originally. If applicable, Re-attach the security cover, gland nut cover, or NL4 cover.
Figure 3:
EVF/EVH Woofer Test
Figure 4:
EVF/EVH Compression
Driver Test
Figure 5:
EVF/EVH Protection
Network Test
Experienced technicians may perform more
sophisticated tests by connecting specialized test gear in place of the ohm meter.
Note: EVF low-frequency systems have no PTP or compression drivers, and use different woof-
ers. See the chart on page 4 for correct DCR values.
5.0 4.3 1.1
(16 Seiten)
(2 Seiten)
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