2270 - Impressive Phono Stage - leave it or recap?

Discussion in 'Marantz Audio' started by bobins08, May 14, 2017.

  1. bobins08

    bobins08 AK Subscriber Subscriber

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    I picked this Receiver up used about 6 years ago. Cosmetically its average, the Seller is an electronics tech and he replaced the left channel output and driver transistors which were blown when he got it. He reset the bias and idle current, treated the controls and switches with de-oxit and done. No recap, no major restoration but I bought a solid performer that was properly tested and set up.

    For a short time I used it as my main power source, then as my preamp stage with my restored Hafler DH 220. Most of the time over the years it has sat on a shelf but recently it is back in use in my home office powering some lovely ADS L690's. I am totally impressed with the 2270 internal phono stage.

    First I had my Vista Audio phono stage connected to the line stage (AUX) on the 2270. After a few weeks I decided to try the Marantz phono input and WOW. It is quite good. I switched back to Vista again for a week, then back again. WOW! The 2270 phono input is on par with the Vista Audio. It lacks some of the high end sparkle and liquidness you get with the Vista but it makes up for it in other ways. It has a wide sound stage with deep bass and rich smooth midrange. Like the Vista Audio, it has a very black and very quiet background.

    I have been thinking of keeping it as my long term office receiver. Because of its age I am thinking of recapping it but I would hate to recap it and lose the goodness that is there.

    Most of the recap threads say the effort is well worth it and there is lots of recommendations on parts to use. I can definitely see the benefit for main filter caps and power supply filter caps. Regarding the phono stage, is there any advice on what NOT to do?

    Thanks, Bob
     
  2. hirscwi

    hirscwi AK Subscriber Subscriber

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    Indianapolis
    The 2270 uses 2 SC458 transistors. These are known to fail. I'd replace them with KSC1845 - gain code "F".

    It's definitely worthwhile to replace the electrolytics (including the tantalum electrolytics) with good quality. There are lot's of recommendations in this forum. I prefer Nichicon Muse or Elna SILMIC II.

    After recapping and replacing the transistors you should set the clipping level. The easiest way is to set the collector of H705 to about 17VDC with R708 and the collector of H706 to about 17VDC with R709.
     
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  3. bobins08

    bobins08 AK Subscriber Subscriber

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    @hirscwi

    Thanks Bill. I appreciate you sharing your knowledge.
     
  4. sssboa

    sssboa Active Member

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    357
    It's not really much of a job. It's usually one electrolytic cap 100uF 50v and 2x tantalum 22uF 16v. There are 4x myllard caps 0.47uF which people sometimes upgrade to 1uF film usually combining with upgrade of the 100uF elecyrolytic to 220uF.
    I stayed with original specs.
     
  5. sssboa

    sssboa Active Member

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    357
    I have originally 2SC1775 not 458. Would you still replace them?

    sc.jpg
     
  6. hirscwi

    hirscwi AK Subscriber Subscriber

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    Location:
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    I don't see any reason to replace the C1775 transistors.

    but if you have the VD1122 and VD1212 diodes (these look like a small bead on a very thin wire) they should be replaced:

    · If H709 looks like epoxy bead, replace with 2 (two) 1N4448 diodes in series

    · If H707 & H708 look like H709 replace with 1 (one) 1N4448 diode – each
     
  7. sssboa

    sssboa Active Member

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    357
    Yeah, thx, I replaced the bead diodes.
     
  8. Scotteboy

    Scotteboy AK Subscriber Subscriber

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    All stellar advice, been doing almost all this on all my restorations and now some more to add ! Thats why I love this forum !
     

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