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  1. LesE

    Pioneer SX-828 diagnostic/repair assistance needed

    Here is the schematic of the amplifier assembly showing the calculated voltage values for all of the transistor leads. Hope it helps.
  2. LesE

    help locating Pioneer A 71 service manual

    It would be interesting to know if any of the circuit board part numbers in the A-71 match the part numbers in the A-858.
  3. LesE

    help locating Pioneer A 71 service manual

    This indicates that the A-858 is the 220/240V version of the A-71. https://www.audioservicemanuals.com/p/pioneer/pioneer-a/pioneer-a-858/2456191-pioneer-a-858-service-manual The A-71 manual on eBay is likely the additional manual (KU/CA) refered to in the A-858 document and may be the only...
  4. LesE

    Spec-1 & Spec-4

    https://drive.google.com/file/d/1g8gqWbq_4mkDE3S3QHCupDc2g5656fu9/view?usp=drive_link https://drive.google.com/file/d/1U5zIhSgbs1ZFgP7oNlaBXgQDvEyWcPvW/view?usp=drive_link
  5. LesE

    Adcom GTP-750 Service Manual

    https://www.audioservicemanuals.com/a/adcom/adcom-gtp/9419936-adcom-gtp-750-service-manual
  6. LesE

    SX-980 Balance pot

    A comparison to an SX-1080 should be valid since both the SX-980 and SX-1080 use the GWG-112 Flat Amplifier Assembly with an ACV-190 balance control. Here is a photo from @RS Steve 's SX-1080 thread which shows that the shaft of the balance control is short. Here is the same SX-1080 with...
  7. LesE

    SX-1010 - no bias no offset

    You may also want to try decreasing C5 from 4.7uf to 2.2uf. This will allow the protection relay to drop a little sooner when powering down which may be sufficient to suppress the pop you are experiencing. The following shows how this change affects the relay coil current upon power down. In...
  8. LesE

    Pioneer VSX-D1S capacitor question.

    For future reference, here is a list of the capacitor types used by Pioneer. Capacitors with the "CE", "CSS" or "CSY" part number prefix as listed in the service manuals are "Aluminum Electrolytic" type.
  9. LesE

    Best Way to Connect a RG-1?

    Yes, that should be fine. Welcome to Audiokarma!
  10. LesE

    SX-1250 issue

    Here is the service manual. https://drive.google.com/file/d/1Tr2EDRlOKA8fytESnw3Kp3qjNsg2iGnW/view?usp=drivesdk
  11. LesE

    PIONEER: Serial number -> production year?

    I can say with complete certainty that the W prefix is 1976. I purchased my PL-530 new on Jan 22, 1977 and the serial number prefix is WK which has to be November 1976. I also have an SX-1250 that I purchased on May 1978 which has a serial number prefix of WH (August 1976). In this case, I...
  12. LesE

    Avid 105 speakers

    From High Fidelity November 1975
  13. LesE

    Roy Allison / RA labs speakers

    Here is an RDL Acoustics and RA Labs product brochure. Unfortunately, some of the pages are a little fuzzy. https://www.classicspeakerpages.net/library/allison/rdl_acoustics/rdl_acoustics_ra_labs_broch/
  14. LesE

    SX-880 left channel volume stays on even when turned down

    ACV-161 was also used in other models.
  15. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Replacing those caps should be fine. You can also replace Q8 & Q9 (2SA725) although that won't solve your problem. Pin 20 receives 13V directly from the power supply board and it isn't switched. Pin 3 also gets 13V from the power supply board but it is routed through the function switch. Pin...
  16. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Yes, your voltages all look great. As for the FM, check to make sure that the B+ voltages to the AWE-043 Tuner Assembly are present and that the grounds are solid. Your plan to revisit the function control is a good idea since one of the B+ voltages are provided to the tuner through that...
  17. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Sounds like you're good to move on to the other issues.
  18. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Do you get lights and relay click with the fuse removed? I suspect that with the fuse removed, you are measuring the path through the transformer secondary windings and the cold lamp filaments.
  19. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Oh, I see. I misunderstood. Pins 1 & 2 are shorted because those two pins are connected through the fuse so you're good.
  20. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    As you mentioned, pin 2 provides AC voltage to pin 12 on the protection board. When the receiver is powered off, this AC voltage disappears which the protection circuit detects and immediately drops the relay to prevent a thump from reaching your speakers. This same voltage also drives all of...
  21. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Good work! We'll need to address the jumper that's shorting pins 1 & 2 when you're ready.
  22. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Previously, you measured -35.6V on pin 7 and pin 7 is connected directly to one side of R2 so one side of R2 should read -35.6V. Check to make sure you have continuity between pin 7 and R2.
  23. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    I just noticed from your previous readings that Pin 7 is -35.6VDC which is good. Perhaps check the voltage drop across R2 to determine the current flow when you get back to it tomorrow.
  24. LesE

    Pioneer SX-737 Restoration - No Relay Click or Sound

    Is the 1A fuse healthy?
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