CR1020 Restoration Guidance

Discussion in 'Yamaha' started by LFazio51, Nov 25, 2017.

  1. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Location:
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    Good afternoon all and Happy Holidays! Hard to believe 2017 is almost over (sorry for the overused cliche')!

    I recently acquired a CR1020 with the intent of restoration. I'm short on experience (other than over a year of research prior to engaging) but am diligent towards educating myself in order to gain the necessary comfort level to proceed with the actual work. Upon power-up (w/DBT) the unit is very distorted on one channel while the speaker protect relay "buzzes" in place. Given the age and desire to restore it, I shut it down and began inspecting and learning my way around it.

    Upon inspection , it became clear that the design of the e.cap board, coupled with the power supply board that houses the speaker protect relay, leaves much to be desired; likely the reason behind the service bulletin calling to replace resistive components due to heating. The left side of the power supply board on my 1020 is situated directly over the left (relative to board placement) diode rectifier on the e.cap board and is severely discolored due to this heat. I'm almost certain that the additional heat generated by this design has also shortened the life of many capacitors on the left side of the main power supply board. Implementing the SB and replacing faulty capacitors seems to be in order for proper restoration. I'm looking for additional research in this task and was hoping to capitalize on some veteran knowledge in order to properly prepare myself prior to initiating repairs - any advice and direction would be greatly appreciated.

    I've also noticed that there are quite a large quantity of capacitors and small transistors on the main power supply board as well. The (2) transistors in the middle of the board, attached to heat sinks (I believe TR712/715 - SD284/SD880) look to be very lose. I'll test once I secure a tester but I'm a little hesitant to replace ALL caps since there are so many. Again, I would certainly welcome any direction in this area as well.

    Working on the main power supply board would seem to require complete disconnection if your goal was to gain easy access for soldering such small components as well as properly cleaning it, and, gaining easy access the e.cap board below. As previously stated, I'm absorbing ALL advice and recommendations.

    I've not ventured into the main power amp boards as my initial thoughts were to gain easier access once removing the power supply board and e.cap board if recommend by others. I'm sure there is a wealth of knowledge concerning this component of the unit and any advice would be most gracious.

    I'm not going to concern myself with the pre-amp/tone, phono, or tuner board until restoration of the power supply board is complete; I'd like to know clean supply is available before troubleshooting or simply upgrading capacitors and transistors on this board. I believe this to be the proper approach but sometimes, due to the level of disassembly, I also realize that it may make sense practically due to access. Overall direction on "repair logic" with respect to sequence would go a long way to point me in the right direction.

    I plan to source the 12v 60ma lamps (incandescent) from David Wojnarowski and have learned that these are wired in "series" but they don't look like it. In fact, they appear to be soldered to pins "LB, LC, & E for the dial pointer where it seems like they should be wire-wrapped. They are also not the typical "red/white" leads, rather solid white for both terminals. If considering connectors LB & LC situated along the bottom left side on the power supply board (while viewing the unit from the front), the (2) bulbs connected appear to have a leg going to each of these terminals - that looks to me like they're in parallel and, along with the solder, causes me to believe someone else may have incorrectly attempted to replace them (photo below). Any advice or diagrams to confirm how these lamps should connect would be very helpful.

    On to parts procurement. I know that capacitors can be sourced from Mouser or Digikey, however, cross-referencing and sourcing components such as the proper transistors, speaker protect relay, etc. is not something I'm too familiar with. If anyone can help in this area it would save me a great deal of time, but more importantly, give me a fighting chance at restoration, rather than blowing-up my unit as a result of using an incorrect transistor (i.e. TR712/715), etc.

    Finally, the CR1020 manual from HFE and AK appear to be severely lacking in clarity, if anyone has a reasonably better copy, or can direct me to one, many thanks!

    Thanks for indulging me on such a lengthy post but I was hoping to properly convey my status so those able to help would take an interest and do so. I've posted some pics that may help with anyone that has some additional questions concerning yearly design; seems to me that Yamaha may have modified the e.cap and power supply board config in later years - I believe mine would be an earlier model. Again, I think most can see my status with regards to this project and where I need to go, so, thanks for reading and much appreciation in advance for all your advice and support.

    Happy Holidays and Merry Christmas!

    CIG_IMG009.jpg

    CIG_IMG028.jpg

    CIG_IMG037.jpg
    IMG_0347.JPG
     
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  2. avionic

    avionic " Black Knights " Subscriber

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    Series - parallel...
     
  3. avionic

    avionic " Black Knights " Subscriber

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    OEM was wire wrapped. Those have be replaced before if they were soldered.
     
  4. avionic

    avionic " Black Knights " Subscriber

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  5. avionic

    avionic " Black Knights " Subscriber

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    Location:
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  6. avionic

    avionic " Black Knights " Subscriber

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    Service bulletins were for the CR-2020..Not really needed in the CR-1020.
     

     

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  7. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Location:
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    First, thanks so much for the information. I've not had a chance to "link-up" to everything you sent but will definitely do it as soon as I get a chance.

    I guess I'm a little confused by "series-parallel." I've attached a photo of the manual below and a hand drawn sketch of my understanding of series. I'm certain I'm confused as more may be happening under the board on the trace but I really can't see that area at the moment. I'd really like to better understand this as they certainly look to be in parallel to me. Is the "series" connection on the underneath side of the circuit board?

    IMG_0348.JPG

    IMG_0351.JPG
     
  8. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Location:
    Beaumont, Texas
  9. avionic

    avionic " Black Knights " Subscriber

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    Very HiQ color pdf files. Norman is the bomb..
     
  10. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Sir, I just noticed that you were retired USAF. I'm honored that you took the time to respond and "THANK YOU FOR YOUR SERVICE!"
     
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  11. avionic

    avionic " Black Knights " Subscriber

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    No need to " Sir" me. I work for a living.:D But thanks anyway..:thumbsup:
     
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  12. LFazio51

    LFazio51 AK Subscriber Subscriber

    Messages:
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    Location:
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  13. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Location:
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    That manual is "da bomb!" Very nice - thanks much! :banana:
     
  14. avionic

    avionic " Black Knights " Subscriber

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    I told you they were..:thumbsup:
     
  15. avionic

    avionic " Black Knights " Subscriber

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    I usually disconnect the two blue fuse wires and the short black (E) wire, on the opposite side of the board, from the lug on the e-cap board with the two blue wires. That should give you enough slack to flip the board over.
     
  16. Mrv8q

    Mrv8q Well-Known Member

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    Thanks to the OP and Avionic, I’m going to follow this post.
     

     

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  17. avionic

    avionic " Black Knights " Subscriber

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    If you choose to re-cap the e-cap board. Pay close attention to the capacitors current polarity. The silkscreened (+) mark is wrong for one of the smaller caps.
     
  18. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Location:
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    YES! I can see where that it would - will try it in the morn (unless curiosity gets the best of me tonight!)

    Concerning the e.cap board, I noticed that the manual indicates both filter caps are 18,000/71v yet the ones the ones installed are only 15,000/63v. Is this common? Sorry had to ask as it's been bugging me. I doubt the large ones are bad but I'll test them, along with the others, I have to say, regardless of their condition, given the amount of "tear-down," it may be prudent to replace.

    I can't thank you enough for this advice Avionic!
     
  19. avionic

    avionic " Black Knights " Subscriber

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    LOL the E-cap schematic is correct for the CR-2020 (Uses the same board) ie 18000µf/71 vdc
     
    Last edited: Nov 25, 2017
  20. avionic

    avionic " Black Knights " Subscriber

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    DSC03600.JPG
    In this photo the lower brown cap , close to the thumb, is installed wrong
    IMG_0584.jpg

    The top photo is and untouched board.
     

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