Teac-MV-8080G-Service-Manual电路原理图.pdf
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1、Service Manual Video Cassette Recorder NO.289C3090 MV-8080G MV-8080G_1 Cover97.12.10, 20:35Page 1Adobe PageMaker 6.0J/PPC RadioFans.CN 收音机爱 好者资料库 Quick Reference of Specific Parts List (Latest upgrade list Dec. 97) The parts No. of Deck Mechanisms, Face Plate Assy and Video Circuit Boards for MV-808
2、0G. CABINET sound is produced by contact between the tip of rotating heads and the edge of the tape. 2. If the tape slips downward; the tape curls or wrinkles (or makes noise) at its connection with the lead face of the drum lead. 3. During loading, play, and unloading of the cassette tape, observe
3、the tape at the supply guide roller, and take-up guide roller. 4. Make sure that there are no curls or wrinkles as shown in the figure below. Guide Roller 5. Observe the tape as it wraps around the drum during PLAY and separates from the drum during STOP. 6. As shown in the figure below, make sure t
4、hat there is no damage to C and D and that there is no contact noise between the head tips and tape edge. Drum Lead Check-2 7. If a defect is detected during check, perform the follwoing procedure for adjusting Guide Roller height. C D ?o? ?K?C?h? ?e?v ?h?A?Z?u? ?“? ?K?C?h? ?h?h Tape Upper Drum Assy
5、 Drum Lead Supply Guide Roller Take-up Guide Roller ?K?C?h? ?l?W ?h?C?o? Turn with a standard screwdriver Guide Roller Tight Screw MV-8080G_5(616)97.12.11, 9:36Page 10Adobe PageMaker 6.0J/PPC 11 4-3. TAPE TRANSPORT CHECK AT THE TAKE-UP GUIDE In general, no adjustment will be necessary for the take-
6、up guide. However, adjustments or checks will be necessary when replacing the Audio/CTL Head or parts affecting the tape transport system after a long period of operation. 1. Using an ordinary cassette tape, set to PLAY mode. 2. Turn Audio/CTL Head screw C as shown in the figure below and adjust for
7、 smooth transport at the Take-up Guide. 5. INTERCHANGEABILITY ADJUSTMENT Before using the test tape, make sure that the tape transport is normal using an ordinary cassette tape. Also, make sure that the switching point (Refer to P.5) is adjusted. If they are not, do the following checks after adjust
8、ing. 5-1. PRELIMINARY CHECKS 1.FM Envelope Waveform Check 1. Connect the CH-1 oscilloscope to TP of PB ENV and CH-2 to TP of CTL. At this time, trigger the oscilloscope externally with the signal (RF Switching Pulse) from TP of RFS. 2. Play the test tape (Stairstep). 3. Use the Channel /5 buttons to
9、 tune the tracking to center position. Adjust point 4 (X value adjustment point: test point reference P.6) so that the FM envelope output at TP of PB ENV reaches a maximum. ?“?K?C?h ?e?v ?e?v ADBEC Tape Tape Take-up Guide 4. Using the Channel /5 buttons. Perform the following 3 steps (5-7) by moving
10、 the TP of CTL waveform in both positive (+) and negative () directions in 3 ms increments. 5. Refer to the figure below. Read the level of portion (a) of the waveform. If the waveform is serrated at point (a), adjust the level so that the serrations are as smooth as possible (refer to the second fi
11、gure). FM Waveform (Maximum Output) Normal Waveform Examples Ideal FM envelope a abd ce Minimum levelMaximum level X?|?W?V?A?W?X?g? X position Adjusting Jig MV-8080G_5(616)97.12.11, 9:36Page 11Adobe PageMaker 6.0J/PPC 12 5-2. ADJUSTMENT 1. Connect the TP of PB ENV to the oscilloscope CH-1. At this t
12、ime, trigger the oscilloscope externally with the signal (RF Switching Pulse) from TP of RFS. 2. Play the test tape (Stairstep). 1.DRUM INPUT ADJUSTMENT 1. Observe the FM envelope output wave at the TP of PB ENV with the oscilloscope and press the CHANNEL /5 buttons in both positive (+) and negative
13、 () directions. 2. A of the following figure shows incorrect waveforms. With a standard screwdriver, adjust the transport guide roller to flatten the peak of the FM envelope waveform as shown in B. NOTES: 1. If the guide roller rotates freely, tighten the screw slightly. 2. Be sure to adjust the gui
14、de roller only by small increments at a time to avoid damaging the test tape. In addition to observing the waveform, make sure that there is no slipping of the tape or curling at the drum lead. = c a d a= c a e a 0.75 and 0.75 or 20 log= 2.5 dB and 20 log= 2.5 dB 0.75 or 20 log 2.5 dB = b a b a 6. A
15、s shown in the equation below, read the FM waveform value at point (b) and make sure that: 7. Read the values at points (c) and (d) drum input and output and make sure that: NOTES: 1. Read the minimum levels for (b), (c), and (d). 2. If above checks yield normal results, proceed to page MA-8 section
16、 “ADJUSTMENT”. 3. If defects are noted, perform the following FM envelope waveform adjustment. 2.FM ENVELOPE WAVEFORM ADJUSTMENT 1. As in the previous section, observe the FM waveform and press the CHANNEL /5 buttons. Waveform alterations must be nearly parallel to each other as shown in Figure “Nor
17、mal Waveform Examples” on page P.11. 2. If the waveform changes as shown in the figure below, adjustment is necessary. Abnormal Waveform Example Drum Input Adjustment Drum input AB Supply Guide RollerTape Tight Screw Supply Guide Roller MV-8080G_5(616)97.12.11, 9:36Page 12Adobe PageMaker 6.0J/PPC 13
18、 2. If there are waveforms as shown in A or B in the above figure, adjust the supply guide roller height so that the waveform appears as shown by E, F, or G in the figure below. At this time, if the waveform fluctuates, adjust to the point of minimum fluctuation. Minimum FM Output (Correct Examples)
19、 E F GTaper Parallel Taper Maximum AC DB NOTES: 1. Fine adjustments are not required at this time. It is sufficient if the tape is engaged with the guide and that the servo operates properly (control signal picked up). 2. If the tape separates from the take-up guide or wrinkling occurs, screw C must
20、 have been excessively tightened with respect to screw A and screw B, which is causing the Audio/CTL Head to incline forward or backward. Use care in adjusting screws B and C, and screw A evenly and observe that wrinkles are not produced at the take-up guide. 5-3. INTERCHANGEABILITY ADJUSTMENT 1. Ob
21、serve the FM envelope output waveform at the oscilloscope and press to adjust the CHANNEL /5 buttons in both positive(+) and negative(-) directions. Minimum FM Output (Incorrect Examples) 3. As shown in the figure below, adjust screws B and C and screw A to align the Audio/CTL Head height with the t
22、ape. Audio/CTL Head Height Drum output CD 2.DRUM OUTPUT ADJUSTMENT 1. Adjust the take-up guide roller so that the FM envelope output flattens as shown in D of the figure below. Drum Output Adjustment 2. If the tape separates from the guide or wrinkling occurs at the take-up guide, adjust by turning
23、screw C of the Audio/CTL Head as shown in the figure below. Take-up Guide ?“? ?K?C?h? ?l?W ABE ?“?e?v?K?C?h ?e?v ?e?v DC Tape Take-up Guide Roller Tape Take-up Guide Tight Screw Approx. 0.06mm Take-up Guide PoleReference line Tape CTL Head Audio Head MV-8080G_5(616)97.12.11, 9:36Page 13Adobe PageMak
24、er 6.0J/PPC 14 3. If the FM waveform appears as shown by C or D in the above figure, adjust the take-up guide roller height to obtain a waveform such as shown in E, F, or G. At this time, if the waveform fluctuates, adjust to the point of minimum fluctuation. 4. Vary the tracking control from maximu
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