Radio Shack MPA-40 инструкция обслуживания

Owner’s Manual Please read before using this equ ipment. MPA-40 20-Watt PA Amplifier 32-2001.fm Page 1 Friday, February 4, 2000 7:53 AM[...]

2 ˆ Contents Features ......... ................ ................ ................ ................. ................ ................ ......... 3 Preparation ....... ................ ................ ............. ................. ................ ................ ......... 4 Presetting th e Controls ................ ................. ..........[...]

3 ˆ Features Your RadioShack 20-Watt PA Amplifier gives you 20 watts of solid power for your PA system. Its wide frequen cy re- sponse easily handles amplification of voice and music. It operates on eithe r 120 volts AC or 12 volts DC power so you can use it anywhere you want to de- liver special announcement s or pl ay mu- sic with great sound. I[...]

4 ˆ Preparation PRESETTING THE CONTROLS Warning: A sudde n high out put from the amplifier could dama ge your hearing or the speakers conn ected to the amplifi- er’s output. To avoid accidentally overdr iving a channel or premat urely amplifying an audio input, se t all the amplifier’s front- panel controls to their lowest set tings. To avoid [...]

5 PHONO/AUX/CD Switch — s elect the input source. Even if you connected auxiliary equipment to both the PHONO and AUX/CD input jacks, you can use only one so urce at a time . Speaker Push Termina ls — press the appropriat e tab to open a ter minal. In- sert the end of a spea ker wire into the opening, then rele ase the tab to close the termina [...]

6 3. T ouch the positive end of a 1 .5-volt flashlight batt ery to the speake r ter- minal that does no t have the wire attached to it. 4. T ouch the negative end of the bat- tery with the lose end of the wire attached to the other speak er termi- nal. Note the direc tion of the cone movement — inward or outward. 5. If the spea ker cone moves out[...]

7 • If you connect more t han two speak- ers using only se ries or only parallel connections, t he total impedance might exceed the am plifier ’s maxi- mum impedance (1 6 ohms) or fall below its minim um impedan ce (4 ohms). For example, if y ou connect fo ur 8- ohm speakers: –In series, the tota l impedance is 32 ohms (8 + 8 + 8 + 8 = 32). T[...]

8 you can make the correct connecti on. The total impedance of all the speakers must match one of the amplifier’s out put terminals ( 4 Ω , 8 Ω , or 16 Ω ) . Speakers in Series 1. T o determine the total impeda nce of speakers connecte d in series, add the impeda nce of all the speakers. For example, if you want to co nnect two 8-ohm spea k[...]

9 If you connect fou r 8-ohm speaker s in series, the total imp edance is 32 ohms (8 + 8 + 8 + 8 = 32). This exceeds the maximum rating. If you connect th ese speakers in paral- lel, the total impeda nce is 2 ohms (8 ÷ 4 = 2). This falls below the minimum rat- ing. You can arrive at a pro per total imped- ance by combining series and parallel conn[...]

10 You need a separa te transformer for each spea ker. Line transformer s have several connec- tors called taps. The primary t aps (on one side o f the transformer) a re the inputs an d are rate d in watts. The secondary taps (on the op - posite side of t he transforme r) are the outputs and ar e ra te d in oh m s. Cautions: • Before you connect [...]

11 3. Connect a wire fr om the speaker ’s positive (+) terminal t o the trans- former’s secondary tap that matches the speaker ’s total imped- ance (4, 8, or 16 oh ms). 4. Connect a wire from the speaker ’s negative (–) te rminal to the COM tap on the transfor mer ’s seco ndary side. ˆ Controls and Operation MICROPHONE 1 and 2 Inputs ?[...]

12 ˆ T roubleshooting If you should ru n into difficulties, che ck the wiring of the system. Are the re any short circuits in th e speaker wirin g? Have you provided adequate ventila - tion? Did you calculate speaker imped- ance corr ectly? Be sure microphon es and connecting cables are not defective. Be sure you ar e using large enoug h speaker w[...]

13 ˆ Care and Maintenance To enjoy yo ur amplifie r for a lon g time: • Keep the a mplifier dry . If it get s wet, wipe it dry immediately . • Use and store the amplifier only in normal tem perature environments. • Han dle the amplifier gently and carefully . Don’t drop it. • Keep the amplifier away from dust and dirt. • Wipe the ampli[...]

14 ˆ Specifications Output Power at 1 kHz, 10% THD ................. ................ .............. ................. .............. . 20 W atts THD at 1W , 1 kHz Low-Pass Filter MIC1 .......... .............. .............. .............. .............. .............. .............. .............. .............. .... 1% MIC2 .......... .........[...]

15 ˆ Notes 32-2001.fm Page 15 Friday, February 4, 2000 7:53 AM[...]

32-2001 81 10816 40B 02A00 Printed in China RadioShack A Division of Ta ndy Corporation Fort Worth, Texas 76102 Limited One-Y ear Warranty This product is warranted by RadioShack against manufactu ring defects in material and workman- ship under normal use for one (1 ) year from t he da te of pu rchase from Radi oSha ck compan y- owned stores and a[...]