Roberts-A-901-90 电路原理图.pdf

crl !- d6a =+ Er l- r+l L Vi ROBERTS MODELS A.9OI. 9q, gO-C,9O-S 7 L/ 2l:ps L/ 2 Hour I Hour 5 o .i, tno d6 o.) sd |Jl Eg o o d, n o E tE la iE oF ola ffi-ffi RadioFans.CN 收音机爱 好者资料库 l. 2. Remove lid from camying case. Remove microphone and AC supply cord from storage compartment on left side of canying 0n-0ff Switch On the Model g0, tis is a 2-position switch. When it is in the On position, power is turned on to the amplifier and tape deck. On the Models g0-S and 90-C, it is a 3-position switch. When the switch is pushed to the AII On position, power is turned on to the amplifier and tape deck. When it is in the Amp Off position, power is applied to the tape deck only. The Off position turns the power off to the entire unit. Vol ume Turning this control clockwise increases the volume in either record or playback. Turning it counterclockwise decreases the volume in either re- cord or playback. Tone This control firnctions inplayback only. Turning it clockwise from position 5 will increase the treble response; turning it counterclockwise from position b will attenuate tie response. Play-Record and Record Lock This is a 3-position control: Stop, play, and OPERAT ING Threading the Tape l. Place a full reel of tape on feed reel spindle (6?), making certain the reel slots engage the protrusions on the pan. place an empty reel on take-up spindle (2?), again making certain the slots engage the protrusions on thJpan. 2. Unwind about 14 inches of tape from the supply reel. Hold a section of tape taut and insert into the tape slot, making sure the dull-coated side faces the rear of the recorder. 3. Insertthe freeendof thetape intooneofthe slots inthe hub of the take-up reel. While holding the end in place, turn the reel two orthree times to secure tte tape to the reel. To Make a Monaural Recording I. P-lug a microphone into the Microphone jack, or place a signal from some other sburce into tre Line Input jack. 2. Depress the Record Lock and simultaneously turn the Play-Record control to ttre Record po_ sition. 3. Adjust the Volume control until the average reading on the VU meter is -b. Page 2 P REPAR ING FO R O PERAT ION case. 3. Make certain all tion- controls are in the Stop posi- FUNCTIONS OF CONTROLS Record. Turning this control clockwise from the Stop position places the unit in ptay. Depressing the Record Lock and turning the control to the Record position at the same time, places the unit in Record. NOTE: This control is interlocked with the Wind- Rewind control. It must be in the Stop position bef ore ttte Wind -Rewind c ontrol can be op e rated. Wind-Rewind Turning this controlto the left places tlreunit in ttte Wind position; to the right, in the Rewind position. NOTE: This control is interlocked with the play- Record control. It must be in the Stop position before the play-Record control can be operated. Pause When this lever is raised, pressure is removed from the drive capstan, and the take-up reel is dis_ engaged. This permits spot editing and momentary stops. NOTE: This control is not on the Model g0. INSTRUCTIONS CAUTION: Do not connect a speaker or other low- impedance load to the Output jack while making a recording. To Make a Stereo Recording l. Connect the interconnecting cable from the Channel-2 head jack to the stereo channel inthe Model 4-901 amplifier. 2. Move the On-Off switch on the tape recorder to AII On. Move the On-Off switchon theamplifier to On. 3. Turn the Volume control until the VU meter reads -5. 4. PIug microphones into the Microphone Input jacks, orplace signals from another sourceinto tte Line Input jacks. 5. Depress the Record Lock and simultaneously turn the Record-play control on the tape trans_ port to Record. 6. PlacethePlay-Record switchon A-g0Iamplifier in Record. ?. On Model 90-C, turn the switch on the built_in preamplifier, on bottom of the case, to Out. RadioFans.CN 收音机爱 好者资料库 FIG. I TOP VIEW OF MECHANISM WITH ESCUTCHEON REMOVED. F o E tT ta 8g F our ti 7 F It/lonaural Playback 1. Thread the tape (see Threading the Tape). 2. Turn the unit on and allow a few seconds for it to warm up. 3. Turn the Play-Record control to Play. 4. Adjustthe volume andtone to thedesired listen- ing leveI. Stereo Playback l. Thread the tape (see Threading the Tape). 2. Turn the tape recorder switch to Alt On. Turn the A-90I amplifier switch to In. 3. Connect the interconnecting cable from the Channel-2 jack of the tape recorderto the Stereo jack on the amplifier. 4. Make certain the Play-Record switch on the amplifier is in Play. 5. Turn the Play-Record controlon the tapetrans- port to Play. 6. Adjust theVolume controls onthe tape recorder and amplifier to a balanced output. Speed Change To change the tape from 7 V 2 to 3 3/ 4 ips, re- move the thumbscrew and bushing from the capstan. When the bushing is not being used, store it on the bushing post. lndex Counter After atape is threaded onthe recorder, set the Index Counter to 000. The index numbers can then be noted at the beginning of each selection, for future reference. External Speaker An external speaker may be plugged into the Output jack. The internal speakerwill be fusconnected when using an external speaker. Erasing Tape To erase one track of a tape, turn the knob on top of the head clockwise. This raises the erase head tothe half-track position. To erase both tracks at the same time, turn the knob counterclockwise. This Iowersthe erase headto the full-track position. When the unit is in the Record position, the erase head is automatically positioned before a new recording is made. To erase the tape without putting a new re- cording on it, turn the volume to minimum and the Play-Record control to Record. To Use the Second Track (ltylonaurall l. Turn the Play-Record control to Stop. n O I n u) Page 3 I I 2. 3. Remove the reel containing the tape, and place it on the left (supply) reel spindle. Place the empty reel on the right (take-up) reel spindle. To Remove Tape Transport Mechanisn from Case I. Remove the two screws in the spindle pans (one in each pan), 2. Remove the two screws holding tle dress plate, and remove the dressplate. 3. Remove one screw on the right side of the es- cutcheon and the 7 V2-tps bushlng from the left side. Remove the pressure roller. Remove the Play-Record and Wind-Rewind knobs. Remove the escutcheon. Remove the four screws holding the tape trans- port to the case. Unplug all connections to the tape transport and speaker, and lift the tape transport from the case. 9. To reassemble, reverse the foregoing proce- dure. To Remove Amplifier from Case l. Remove the four screws holding the amplilier and escutcheon to the case. 2. Unplug all connecting plugs. Record-Playback Head Alignment With Standard Alignment Tape l. Thread the tape (see Threading the Tape). 2. Connect a 0.5-volt AC voltmeter to a standard phono plug, and insert the plug into the Output jack. 3, Turn the Tone control to maximum. 4. Remove thetwoscrews fromthehead cover, and remove the head cover. 5. Insert a screwdriver, through the hole in the head shield, into the alignment screrr. 6. Play back thetape at full volume, and rotate the 4. Thread the tape, and proceed with the recording as described under To Make a Monaural Re- cording. D ISASSEMBLY ADJUSTMENTS LU BR ICAT ION Lift the amplifier from the case. To reassemble, reverse the foregoing proce- dure. To Renove Prean:p fron Case on A4odel 90-C l. Remove the two screws from the bottom of the case, 2. Unplug aII connecting plugs. 3. Lift the preamp from the case. 4. To reassemble, reverse the foregoing proce- dure. To Remove Model A-901 Anplifier fron, Case l. Remove the four screws holding the amplifier to the case. 2. Remove the four screws holding the speaker cover on, 3. Disconnect the speaker. 4. Feed theAC cord throughthe hole inthe storage compartment. 5. Lift ttre amplifier from the case. 6. To reassemble, reverse the foregoing proce- cure. 3. 4. 4. 5. 6. t - 8. alignment screw in either direction until the 10,000-cycle note givesthe highest meter read- ing. Record-Playback Head Alignment With Con mercial Music Tape 1. Thread the tape (see Threading the Tape). 2. PLay back the tape at a normal listening level, and adjust the head alignment screw for maxi- mum clarity of high-pitched instruments. Brake Shoes When brake shoes (34) and (80) become worn, loosen the mounting screws and rotate the shoes a few degrees until a new braking surface is exposed. Lubricate the following parts every three months Page 4 in heavy service, every six months in moderate ser- ffi -ii,:., _.rN, tvr tl.: .: :!F.-l ffii:-;i-,.,.1r, :#;* :. . . .f * - rrlr :.- -L speaker hum, and VU meter 2. Defective output tube. 2. Replace output tribe. does not read on record. No record or playfack, but l. Preamplifier tube defective. I. Replace preamplifier tube. slight speaker hum variable with volume control. Noisy playbackor poorhigh- I. Heads misaligned. I. See Head Alignment. frequency response. 2, Heads magnetized. 2. Dernagnetize heads. Wow or flutter at? L/2-ips 1. Speed change bushing slip- l. Tighten screw (120). speed. ping on shaft. lnsufficientdrive at? L/ 2-or I. Defective main drive idler l. Replace main drive idler 3 3/4-ips speeds. wheel (3i). wheel (3I). 2. Oil on capstan. 2. See Cleaning. 3. Main drive belt (8) defec- 3. Replace main drive beft (IlB). tive. 4. Drive motor(I24)or starting 4. Replace drive motor (I24) or capacitor defective. starting capacitor. Tape spills when going f rom I. Reel diameters unequal. l. Tape reels mustbave the same wind or rewind to stop. diameter. 2. Brake shoes (34) and (80) 2. Replace oradjust brake shoes worn or out of adjustment. (3a) and (80). lndex Counter does not I. Counter belt (I27) worn or l. Replace counter belt (127). function. broken. MECHANICAL PARTS LIST Ref . No- Part No.Description I 2 3 4 5 6 7 I 9 l0 n t2 l3 t4 l5 r6 l? t8 l9 20 20A 2T 90-50-43 90-50-r5 90-50-47 90-50-64 90-52-27 90-50-16 90-38 90-50-22 90-50-r? 90-50-30 90-50-89 90-50-79 90-50-81 90-50-80 90-52-23 90-52-r2 90-50-94 90-50-32 Reel Table Screw(2) Reel Table (2) Pinch Wheel Screw Pinch Wheel-Models 90 lirigfiffi 9O-C AMP. CHASSIS TOP VIEW. 9O.C AMP. CHASS IS BOTTOM V IEW. 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