Altec-Lansing-438-A-Schematic 电路图 维修手册.pdf

《Altec-Lansing-438-A-Schematic 电路图 维修手册.pdf》由会员分享，可在线阅读，更多相关《Altec-Lansing-438-A-Schematic 电路图 维修手册.pdf（4页珍藏版）》请在收音机爱好者资料库上搜索。

1、SPEClflCATIONS Type: Gaiin: Input Sen1itlvity: Maximum Compresaion: Power Output: Frequency Re1pon1e: Input Impedance: Source Impedance: Loaid lmpedaince: Nolae Level: Control1: Power Supply: Tube1: Dimen1ion1: Color: Weight: Speciail FHture1: Attaick Time: Recovery Time: Humonlc Distortion: Acce110

2、rlea: Compressor Amplifier 438A AMPLIFIER OPERATING INSTRUCTIONS 90 db from Microphone input; 40 db bridgin9 600 ohm line 6.5 millivolts on Bridging input to reach compression threshold 30 db (50 db change in inptt results in 20 db change in output) + 19 dbm at 30 db compression; +24 dbm os straight

3、 amplifier : 1.5 db, 40 to 10,000 cps Bridging, 20,000 ohms unbalanced Microphone input, 30/50 ohms 150 and 600 ohms Gain control at max., -119 dbm equivalent input noise, Microphone input Gain control al min., -50 dbm output noise level Gain, AC power switch 117 volts, 60 cps, 22 watts 12A Y7, 6BC8

4、, 6CG7, 6Al5 19 L, 3 H, 6 D Metallic Gray 8 lbs. Compression meter 50 milliseconds 1 second for 63% recovery At 25 db of compression, less than 1.5%, 35 to 15,000 cps At 30 db of compression, less than 2.5%, 35 to 10,000 cps 12495 Cabinet 1515 S. Manchester Ave., Anaheim, Calif. New York. leverly Hi

5、lla, Loa A9ele1 ALTE-C 12,03 llIINTl:0 IN U A fade background music for -ents, start with an approximately mid-scale Ille 38A gain control and set the control of the music ,o. that for average music level the compressor threshold ,.,., ched. Proper listening level is then set by means of , power amp

6、lifier gain control. The voice gain controHsl is then 1ocfiusted to provide aprpaximately 25 db of compression, as .i,own on the meter, during normal announcements. If the voice channel has insufficiet gain to provide the latter condition, re- establish all settings starting with a JI 4 or higher sc

7、ale setting fo, the 438A gain control. The above settings will result in announcements at a level approxi mately 15 db above the original music level. Al the same time, during announcements the music will drop automatically to a level about 40 db below the announcement level. D- Compression Meter Ir

8、 is usually desirable to have the compreuion meter visible from the operating position. When condition, dictate a remote location for the 438A Amplifier, an Ailee .;:6049 meter should be ordered for Installation al the console. The additional meter is connected inporollel with the 438A Amplifier met

9、er by means of a pair of wires extended to the console location. Servicing All circuit components ore easily reached by opening the hinged front panel of the unit. Normal servicing can be done with o volt meter. All pertinent information is shown on the schematic. Accessory The 12495 cabinet is a pe

10、rforated metal enclosure and cover which may be used to protect the 438A Amplifier when not rock mount ed. The optional use of the panel cover will discourage unwar- ranted tampering with the panel controls. MASTER fl t/ 341A, 1520A 1530A, 15 70A FIG. I. 438A Amplifier driven by low impedance microp

11、hone and driving any Allee power amphher w1thour added transformer. A 600-ohm terminating resistor must be connected across the 438A output for amplifiers shown. Add fixed or variable attenu otion ahead of 260A Amplifier. ., l I j TRW. !PHONl - -).2 ,.,.- -8RIOGING - - ./AA INfUT MIX r 1 FIG. 2. 438

12、A driven by both microphone and phono circuit for voice-over-music operation. Use R 17 build-out resistor in 1511 A. Al,y equipment substituted for 1511 A must have its own level control and a build-our resillor of at least 40,000 ohms. MASTER vyv j f i /. V 341A,1520A !$JOA, 15 70A FIG. J Typical s

13、ystem ualng Bridging input of 438A Amplifier. The remote master provides proper 1ermination for the -4J8A and the transformer provides additional gain for the power amplirier. PARTS LIST Cl 50Mfd. lV, Co,ell Dvbllie, HI 50-l RI I 33,000 ohm1 = 10, 12 watt C2 .0., Mfd. ,COV, Mico-ld Tropicop _ Cl .00

14、5 Mfd. 600V, OMV Olac, Irle Type II I C4 .5 Mfd. 200V, Hoplli 15.390.u, - 119 _ 47,000 ohm1 = 10% watt 120 10,000 ohm, = -10%-1 wall _ 121-6100 oh;, = 101. 1 wall CJ .000IS Mfd. 600v. Erle 111 . 151 . - Tl C6, 7, I, 9 .0022 Mfd. 400V. MicOfflOld Tropicop _ - CIO 1 ,.;.;:;.:-2oc)v :-Hopkin, -.,_390:-

15、f- T2 -. , . ,leu 46ll Tl-,-leu-16402 c i 1 .0- Mfd-:-450V, Mallory ,-:jfj;9 - u , . , . 6216 Cl2. 13 100 Mfd.1,0I, Mallory ,-116 _ - 11-ifooo ohm, -10%- ;_tt_-_ _ 12 3900 ohm1 :!: 10% watt M 1 Altec_!_on_1,nv - _ Pl I Maida ;: ll 2.0,000 ohm, -10%_-_h-,;,_-;,;_11 _ _ U, 11, 12, 17 I er:!: lo,(, w_a

16、_tt _ _ R5 IIOO ohm1 -lo,(, watt - ,. _ 12 amp JAG Fvu s, _ i1, . -l.;.-.;-;.v-1.21 ao Ree1ifier Sorke, Tanian 58-0 16 100,000 ohmt : lo,(, watt 17, I, 9, 10 47,200 ohm, : l%O.po1ited-C;b.,;- Vl _ 12AY7 V!_uu-_!- _ -=-=- V2 61CI Vacvum Tube lll 220 ohm, :!: 10% wott VJ _ 6CG7 Vac.uum Tube - 11, 1 22

17、0,000 ohm, :!: lo,(, watt v, 6Al, Vocvum T1,1be 116 34 ohm,:!: Ill, ?!potiled Carbon .5CRIPTION ,fie .C38A Comprenor Amplifier is o self-powered unit capable of driving any Alrec power ompiifier to full output from low impedance microphone, and provide at the some lime up to 30 db compression Ir occ

18、upies 31 , . of rock space and is equipped with level control, power switch, fyse, pilot light and compression meter mounted on a hinged front panel. It is provided with two inputs: a Microphone input -equipped wirtton input transformer connected to accommodate o 30/ 50 ohm microphone; and o Bridgin

19、g input of 20,000 ohms imped- ance which may be used on unbalanced lines of any impedance up to that value, or above if the bridging lou is not excessive for the opplicotion. The gain control is effective for either input. Output foods of 150 or 600 ohms moy oe accommodated. The threshold and omount

20、 of comprenion, as well os the ollock and recovery time of the circuit, are fixed quantities considered optimum for overage program service. APPLICATIONS The .C38A Amplifier is intended for use in automatic level control applications in recording, TV broodcosting ond public address sys- tems. level

21、differences caused by individual voice intensities ond unequal distances of performen from the microphone con be minimized by its use. The Bridging input permits the 438A Compressor to be used to control level differences between two or more program sources or for oulomotic fading for voice-over-mus

22、ic announcements. In industrial locotians where sudden high level sounds might cause blast ing with ortendont danger to amplifiers ond loudspeakers, the .C38A Amplifier will prevent such overloading. Altec compressor ompli- fien ore also being used in TV broadcast pickup of variety, dramatic, musica

23、l ond operatic productions to minimize level disparities and to relieve the control operator from the need for over-ur 7, - DOM - . ! . _ i.,. -. ,- 5 C h0 INPUT TSI BLK Woor.r CIIA1 - CI0 I 1.0 -=.c.-r - I I I! I I I 8 I ) v RIB 33K Rl9 I _ ._.Q R 20 47K -.J/V, 130V I0K IW ._ 2:1:IV - . 6eoon. I T4

24、 C12J.+ 100T- 6216 RED St co-JILK I ce- Fl Vt A. + 117 VA.C. T RECTIFIER Jlt - Cl3 I + 100 CIIBI + filf _T _ -t-_ - . J,ilil , -I _ 3r-. r-.r 6.3 V.A.C. c11J.+ 401- _ ) &AL 6C &BC _ l _ 1 _ -_. .I! ALTEc LANSING 438 A COMPRESSOR AM PLI Fl ER CHASSIS 2 -X1 :_ . _ . V3 1 8D I MV l I - I I lur V4 6AL5 BLU 600,J I ro=1 OUTPUT TS 2 2 3 . GNO 3 I() I 3 TS 2 STRAPPING LEGEND J. OHMS K l,OOOl M 1,000,0001. ALL CAPACITANCE VALUES IN NfO UNLESS OTHERWISE INOICATtO . ._.