It's great to be able to obtain a precious technical information for a real old equipment. The one I got helps me a lot in the area of wiring diagram to repair my antique. PDF gave me clear enough information to find out thr details. Thanks for giving me the oppotunity to be able to access to almost vanished informations.
Good quality for the scan, complete, but as usual for Tascam, not so comprehensive !
Text excerpt from page 108 (click to view)
XR-A550MD
¶ The disc motor does not rotate
Do waveforms appear for Pins 24 and 25 of IC1201 at the focus gain rough adjustment step in Test mode? YES Do waveforms appear for Pins 34 and 35 of IC1601 and Pins 1 and 2 of CN1603? YES Replace the DISC MOTOR Assy. NO Check soldering of the substrate of the DISC MOTOR ASSY of IC1601 and CN1601. NO Check soldering and parts of Pins 24 and 25 of IC1201 and the circuits around IC1201.
¶ The tracking servo does not function
Do waveforms appear for Pins 8 and 9 of IC1601, and Pins 1 and 3 of CN1101 at the tracking gain adjustment step in Test mode? YES Replace the Light Pickup. NO Check soldering of Pins 20 and 21 of IC1201, IC1601 and CN1101.
¶ The slide servo does not function
Does the pickup move toward the outer and inner circumference in Test mode? NO Do Pins 22 and 23 of IC1201 change when the pickup moves toward the outer and inner circumference in Test mode? YES Do Pins 28 and 29 of IC1601 and Pins 1 and 2 of CN1602 change when the pickup moves toward the outer and inner circumference in Test mode? YES Does voltage of positive (+) and negative (-) terminals of the Slide Motor change when the pickup moves toward the outer and inner circumference in Test mode? YES Replace the Slide Motor. NO Check soldering connecting to the Slide Motor. Check for disconnection. NO Check soldering of IC1601 and CN1602. NO Check waveforms of Pins 22 and 23 of IC1201. Check parts around IC1201. Check soldering of IC1201. YES Check waveforms of Pins 22 and 23 of IC1201. Check parts around IC1201. Check soldering of IC1201.
