PA-1_Test_Spec 电路图.pdf

TEST SPECIFICA nON: TL Audio PENTODE PRE-AMPLIFIER. Issue 1: 28th February 1995. Tolerance on inputs +/-o.3dB, outputs +/-ldB, unless stated otherwise. I. MAINS VOLTAGE: Set to 240V. 2. GROUND CONTINUlTY: Limit 0.01 ohms. 2.1 Measure the resistance between the ground pin of the IEC inlet to the chassis ground screw. 3. VISUAL INSPECnON: Inspect the unit, paying particular attention to the following items: 3.1 - the orientation of power supply diodes and capacitors, 3.2 - the orientation of ICs, 3 . 3 - all mains wiring, 3 .4 - the quality of external paint and silk screening, 3.5 - check all knobs and switches operate freely and are uniformly spaced from the panel, 3.6 - all XLR connectors are locked, 3.7 - LED alignment with front panel. Tests 4 and 5 should be performed on each channel: 4. PHANTOM POWER: +24V+/-IV. Pentode: 48V On, measure on pins 2 and 3 ofMic input socket with 6K8 termination jig. Check associated LED. Turn off 48V. RadioFans.CN 收音机爱 好者资料库 . 5. INPUTS: 5.1 MIC INPUT: Output OdBu. Pentode: Mic Input, Gain 50dB, Trim 0dB, LF Cut off, HF Cut off, Fader Max, Nominal level +4dBu. A2: 1KHz, Sine, -50dBu, 22-22K Filter, Meter. 5.2 TRIM: +/-12dB. Pentode: Adjust Trim, checking corresponding change in output. Return to OdB. 5.3 GAIN: Pentode: Reduce Gain in IOdB steps, checking corresponding reduction in output. Leave in 20dB position. 5.4 DISTORTION: Limit 0.05%. A2: Level -20dBu. 5.5 FREQUENCY RESPONSE: Limit -2dB, 30Hz-40KHz. A2: 22-22K Filter off, Sweep. 5.6 HF Cut Filter. Pentode: Set HF Cut to 15KHz. A2: Sweep, check -3dB selected frequency. Repeat at 10KHz and 5KHz. Return to Off. 5.7 LF Cut Filter. Pentode: Set LF Cut to 50Hz. A2: Sweep, check -3dB selected frequency. Repeat at 100Hz and 150Hz. Return to Off. 5.8 MIC INPUT NOISE: Limit - 72dBu (EIN = -122dBu). Pentode: Disconnect input and replace with 150R termination, Gain 50dB. Remove termination. 5.9 INSTRUMENT INPUT: Output -4dBu. Pentode: Input to Instrument Jack Socket. A2: Level-4OdBu. RadioFans.CN 收音机爱 好者资料库 i.- 5.10 SIGNAL, PEAK and CLIP LED: Pentode: Gain 20dB, input to Mic socket. A2: Adjust level and check LEDs illuminate at the output levels specified. +/-2dB: Signal -20dBu, Peak +lSdBu, Clip +24dBu. 5.11 NOMINAL LEVEL: A2: Level -20dBu. Pentode: Gain 20dB, check output switches between OdBu and -14dBu. 5.12 FADER: A2: Level -20dBu, nominal level +4dBu. Pentode: Gain 20dB, check output OdBu fader maximum, and fade to no signal. 5.13 OUTPUT NOISE: Limit -85dBu. 6. PHASE. 6.1 PHASE: Limit 0 +/-2deg. Pentode: Adjust channel A Gain for -OdBu +/-3dB output. A2: Phase (needs OUT B to CH B cable). 6.2 PHASE REVERSE: Limit -180 +/-2deg. Pentode: Phase Reverse. 7. SOAK TEST. 8. AUDIO/QA TEST. RadioFans.CN 收音机爱 好者资料库