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SYSTEM
SUPPORT SERVICES 11046 State Road 52, Hudson, FL 34669 ● (727) 243-3656 |
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SYSTEM
SUPPORT SERVICES 11046 State Road 52, Hudson, FL 34669 ● (727) 243-3656 |
This procedure describes how to adjust and test the 30-0002-1 CM-500K Modem in the field. The purpose of this procedure is to provide field personnel with a reliable go/no-go test for the assembly, and to provide the capability of performing certain adjustments. This procedure should not be used as a substitute for routine, periodic, factory alignment of this unit.
If the documents described in this section are available on-line, they will be represented by a hypertext link, which you can click to go immediately to the referenced document.
If they are represented by plain text, then the document is not (yet) available in our on-line library, and must be obtained from SYSTEM SUPPORT SERVICES. Schematic diagrams are proprietary, and will not be available on-line.
| 1. | 35-0002 | Schematic Diagram - CM-500K Modem |
| 2. | 90-0025 | Installation and Operation Guide, Computrol Model 14-0003 Comtrol 1 Remote Tester |
| 1. | (1) | Comtrol 1 remote card cage assembly and power supplies with 30-0001-1 Common Logic board, 30-0016-3 Failure Detect board, and a known good 30-0002-1 CM-500K Modem |
| 2. | (1) | Oscilloscope and suitable probe |
| 3. | (1) | Computrol Model 14-0003 Comtrol 1 Remote Tester with extender board and power lead This unit must have a modem with a known good transmitter installed. If the condition of the modem in this unit is in question, remove it and perform the transmit half of the test procedure on this modem before attempting to use it to check out any other modems. |
| 4. | (1) | Coaxial cable with male PL-259 connector at one end, and male BNC connector at the other end |
| 5. | (1) | Coaxial cable with male BNC connectors at each end |
| 6. | (1) | 75 ohm adjustable attenuator capable of being set to 0 dB and 30 dB attenuation |
| 7. | (1) | 75 ohm feed through terminator, or 75 ohm terminator and BNC "tee" connector |
| 8. | (1) | Frequency counter capable of measuring frequencies in the megahertz range, with suitable test cable |
| 9. | (1) | 30-0002-1 assembly to be tested |
| 10. | (2) | Test leads with mini-hook connectors |
Set up the equipment in Item 1 of the "Equipment Required" section according to the "Initial Hookup of Multiplex Test Set and Cage" in the Installation and Operation Guide for the Computrol Model 14-0003 Comtrol 1 Remote Tester, Document Number 90-0025. Make sure the power to the card cage is turned OFF.
| 1. | Remove the known good CM-500K modem from slot 2 and plug the extender card with the power cable for the Comtrol 1 Remote Tester (item 3) into slot 2 in the card cage (item 1.) Connect the white power connector to the corresponding connector on the tester (J2.) |
| 2. | Connect the end of the coaxial cable (item 4) with the male PL-259 connector to the female PL-259 connector on the tester (J1.) |
| 3. | Connect the other end of this connector to the 75 ohm attenuator. |
| 4. | Connect the other coaxial cable (item 5) to the attenuator. |
| 5. | Connect the other end of this cable to the 75 ohm terminator (item 6.) Do not connect to the card cage at this time. |
| 6. | Using one of the test leads (item 10,) connect pins 40 or 42 (TTM*) to ground (any odd numbered pin except 11, 13, 15, or 17.) Connect on the extender board so modems can be swapped without having to disturb this connection. |
| 7. | Using the other test lead, connect pins 22 or 24 (DOM) to ground. Connect on the extender board so modems can be swapped without having to disturb this connection. |
| 8. | Connect the frequency counter (item 8) to pins 6 or 8 of the card edge connector on the extender board. Set the counters function and range controls to measure frequencies between approximately 500 kHz and 1.6 MHz. |
| 9. | Remove the Common Logic board (part number 30-0001-1) from slot 4 of the card cage. |
| 1. | Plug the 30-0002-1 to be tested into the extender board in slot 2. | |
| 2. | Turn on the power to the remote card cage. | |
| 3. | Allow the modem to warm up for at least five (5) minutes before attempting any adjustments. | |
| 4. | When the modem is warm, verify that the counter reads between 830 and 870 kHz. If the reading is outside this range, vary R9 until the counter reads 850 kHz. | |
| 5. | Connect signal DOM to +5 volts using the appropriate test lead. | |
| 6. | Verify that the counter reads between 1.55 and 1.57 MHz. If the reading is not within this range, note whether it is higher or lower. Repeat step 6 using a value that is higher or lower to achieve both readings within their required ranges. If the adjustment cannot be performed, the modem is defective and must be repaired. | |
| NOTE: | On boards older than revision G, it is likely that this adjustment cannot be properly made. The board should be upgraded to the latest revision. | |
| 7. | Using the appropriate test lead, connect signal TTM* to +5 volts. | |
| 8. | Connect the oscilloscope to pins 6 or 8 of the card edge connector on the extender (signal "CABLE XMIT".) | |
| 9. | Set the vertical sensitivity to 50 mV per division. Set the coupling to ground, and center the trace. | |
| 10. | Set the coupling to DC. Adjust R39 for a level as close to zero volts as possible. | |
| 11. | Power off the card cage. Remove all test leads, and reinstall the Common Logic board (part number 30-0001-1) into slot 4 of the card cage. | |
| 12. | Remove the modem under test from the extender. | |
| 1. | Connect the free end of the coaxial cable with the terminator (item 7) to the BNC jack J1 on the card cage backplane (it may be necessary to remove one or more cards to reach this connector.) | |
| NOTE: | If the card cage currently has a coaxial switch installed, disconnect both P1 and P2 from the backplane connectors J1 and J2. | |
| 2. | Install the known good CM-500K modem into slot 2. | |
| 3. | Set the 14-0003 Comtrol 1 Remote Tester as follows: | |
| a. | Once/Cont switch to Cont. | |
| b. | AR0 to AR5 to the binary representation of the Failure Detect Board address (usually 308.) | |
| c. | AR6 to AR10 to the binary representation of the Common Logic Board address. | |
| d. | SS1, SS2, and DAACK low (off.) | |
| e. | DR0 high (on.) | |
| f. | DR1 through DR15 low (off.) | |
| 4. | Set the attenuator to 0 dB. | |
| 5. | Turn on the power to the remote card cage. | |
| 6. | Verify that the LED on the Failure Detect Module is on. If it is not, recheck the test setup, paying particular attention to the address settings of the boards and the switch settings of the Remote Tester. | |
| 7. | If the LED is on, turn off the power to the remote card cage. | |
| 8. | Replace the known good modem with the modem under test. | |
| 9. | Turn on the power to the card cage. | |
| 10. | Verify that the LED on the Failure Detect Module is on. If it is not, the modem is defective and must be repaired or realigned at the factory. | |
| 11. | Set the attenuator to 30 dB. Verify that the LED is still on. If it is not, the modem is defective and must be repaired or realigned at the factory. | |
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Revised: April 24, 2006 .