User manual DRAKE DIGITAL VM2551

[. . . ] VM2551 Commercial Video Modulator (For use in NTSC systems) Instruction Manual is a registered trademark of the R. L. Drake Company P/N: 3852551B-12-2005 2 Caution Statements WARNING: TO PREVENT FIRE OR ELECTRICAL SHOCK DO NOT EXPOSE TO RAIN OR MOISTURE !WARNING!RISK OF ELECTRIC SHOCK DO NOT OPEN CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER NO USER-SERVICEABLE PARTS INSIDE REFER SERVICING TO QUALIFIED PERSONNEL A product and cart combination should be moved with care. Quick stops, excessive force and uneven surfaces may cause the product and cart combination to overturn. [. . . ] F2, F3 - AUDIO LEVEL Control & Audio Overmodulation LED The setting of this screwdriver adjustment determines the peak aural carrier deviation. After installing the unit, and with an audio source connected, adjust for 25 kHz deviation by advancing the Audio Level control, F2, until the Audio Overmodulation LED, F3, begins to illuminate. Monitor for a few minutes to assure that maximum volume of the audio source program does not cause an overmodulation condition. F4, F5 - VIDEO LEVEL Control & Video Overmodulation LED The setting of this screwdriver adjustment determines the video modulation level. After installing the unit, and with the desired nominal 1 Volt P-P video source connected, adjust the VIDEO LEVEL control F4 for the correct percentage of modulation (87. 5%). This connection is normally cabled directly from the "COMPOSITE IF OUT" connector (See R3). This external IF loop allows the use of accessories such as scramblers or alternate video sources. R3 - IF OUT Connector This is the composite IF output from the IF circuits. The composite IF provides a vestigial sideband filtered visual carrier at 45. 75 MHz combined with a level controlled (-15 dBc typical) aural carrier at 41. 25 MHz. This connection is normally cabled directly to the "COMPOSITE IF IN" connector (See R2). R4 - VIDEO INPUT Connector This is the baseband video input to the IF circuits. This input accepts baseband through 4. 2 MHz video at levels from 0. 7 Vp-p to 1. 5 Vp-p. R5 - AUDIO INPUT Connector This is an unbalanced audio input to the IF circuits. This "RCA" (phono) connector input accepts 40 Hz through 15 kHz audio at a nominal level of 250 mV RMS (approximately -10 dBu). R6 - 4. 5 MHz INPUT To use this input, remove the top cover of the modulator and move jumper J2 to the ON position. R7 - 600 W Convenience Outlet This outlet is unfused and must be limited to a 5A or 600 W load at 120 VAC. Do not defeat the safety purpose of the ground pin on the line cord plug. Pull out on the tab on the upper side of the fuse holder assembly. 6 Installation RACK MOUNTING Adequate ventilation is very important in multichannel installations. Units should be spaced apart by at least one panel height wherever possible, and some air movement is advisable in enclosed rack cabinets. Excessive heat will shorten component life and modulator performance will be degraded without proper cooling. USE WITH A STEREO ENCODER An external BTSC stereo encoder may be used with the VM2551. To sett the VM2551 for a flat audio response that will accept the BTSC composite stereo input - remove the top cover of the VM2551. Observing the PCB that contians the Audio, Video, A/V Ratio, and other components, locate the small slide switch - SW2. [. . . ] The unit must be sent to the following address: Service Department R. L. Be sure to include your street address which will be needed for UPS return. UPS Surface (Brown Label) takes 7-10 days to reach us depending on your location, Blue takes 2-3 days. Red is an overnight service. Send the unit in a way that it can be traced if we can't verify receipt of shipment. [. . . ]