tandberg rc-20-servicemanual 维修电路原理图.PDF

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1、TANDBERG Remote Control RC 20 Service Manual s - : -tleJ Batr oo It tl ffi*om Remote Control r ransmitter Remote Control Unit RC 20 The RC 20 remote control svstem uses a cordless, infra-red unit to control the latest Tandberg tape and cassette decks. The system consists of a battery-driven transmit

2、ter, and a receiver which is con- nected to and gets its supply voltage from the tape/cassette deck. The RC 20 transmits information with the aid of infra-red light (IR light) which is invisible to the human eve. The transmitter unit RC 207 Battery life The current consumption for the transmitter du

3、ring use is 12 mA approximately. The battery has a capacity of about 200 mA hours. So the battery will transmit con- tinuously for about 17 hours. Mechanical dismantling The transmitter is held together by two screws. One of these screws is located under the battery. E lectrical description - The el

4、ectronics in the transmitter consists of two circuit boards. one board for the push buttons (A1-1) and one board for the IR unit (A1-2). - The heart of the transmitter is a MOS device SAB 3210 (U1). - When the push buttons are operated, the transmitter is activated and current is applied to U1. - Th

5、e oscillator frequency is about 4Z kHz and it is given by Ll, C2 and C3. - The IR output, pin 8, is now active and the command signals are applied to the base of Q2. - Transistor Q2 is a buffer the output IR, pin 8, and the current generator consisting of CR4, Q3, R8, and R9. - The purpose of the cu

6、rrent generator is to regulate the current through the infra-red light-emitting diodes to about 1.3 A irr each pulse. NOTE ! The transmitter must not be i MO) on pin 18, U1. The circuit should oscillate at about 43 kHz when the buttons are pressed. If it does not oscillate, see point J. 3. Check tha

7、t pin 6, Ul goes low when the buttons are operated. If pin 6 goes low, see point 4. 4. Use an oscilloscope to check that pin 8, Ul has a bit sequence as shown in the table. If not, check the supply leads from the operation buttons and if necessary change U1. 5. Use an oscilloscope to measure the vol

8、tage across R8 and R9. The voltage amplitude of the pulses should be between 0.55 V and 0.75 V. If not. check the diodes and Q3. Receiver RC 20R 1. The receiver is supplied with an unregu- lated voltage of about 14 V d.c. Check at C6 that Ql regulates the voltage to about 10.5 V d.c. 2. Check the re

9、ceiver pre-amplifier with an oscilloscope probe on the collector of Q7. The pulse sequence should be in opposite phase to the pulse sequence shown in table 1. 3. Check Ul with a probe on outputs A, B, C, and D. See table 1. Button operated on the transmitter Output activated in the receiver PLAY STO

10、P WIND REWIND RECORD* (both) WIND and REWIND STOP and WIND STOP and REWIND STOP and PLAY PLAY STOP WIN D REWIND RECORD and PLAY WIND and REWIND STOP and PLAY* STOP and PLAY* STOP and PLAY* I t; It G rF= o6 BC s19C n ct, IF 22 la cl- of T I RECEIVER PRE. AMP A2-1 L-I- CLK 2 UI IR SAB 3209 I I 820p c2

11、 820p RECEIVER DECODE R A2-2 U4 UI, tc J (oT (Jl - vcc ?- r- lc TE RECEIVER ol BC 1858 T:. olo I INTERGRATED CIRCUITS USED U 1 -SAB 3209 . IR RECEIVER U2 -MC.I/.001 B, OUAD2-INPUI NORGAIE (cMos) U3.5 -MC110118, OUADz-II.PUI iANBATE (cMos) U6 -HINIL332, HEXINVERTERGA,TE,OC swt t- rl Fzl f-t ll ll - -

12、 - I I l rr* I I I I uro _ _ _ _ _ _ - - - - - - - - - - cRl tD 271 cR2 LO271 cR3 LO271 so cLcKl CLCKo sb Sc z1 32ro 22 IRA z3 zt, z5 z6 zl z8 ETA UOO I l L cl 1000p TRANSMITTER I R A1-2 ER UT NORGATE IlT MNOOATE TERGATE, F s . ;oa vo o o - - - o1 BC 517 - - TRANSMITTER Transmitter, Keyboard seen fr

13、om solder side. Transmitter, IR-board seen from solder side. _-EE-q- t-; t.l l_: looooool l REwrr; a 1 t-.! i L*. r+tr l .1 1 .l li ?, 1 - ill: lt.:ijli t-Jf1 tEJ 1 - Ut *1EF- F1 l i.f rrs I ,Al*l dl ? d6s-,6JT Receiuer, Pre. amp. board, seen from solder side. R e c eia er, D e c o der b o ard seen from solder side. ,-l I )I )l l )l $l or, I _ll Hl ll -l I I _J - - - - - - s 1 ,Fr*i. YJ: tr q-N o o tr)