Marantz 2275 Restoration - 1974

Discussion in 'Audio Visual' started by aokman, Oct 25, 2009.

  1. Asteroid

    Asteroid Member

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    Cool project bud, vintage audio gear for the win! I'm not a big fan of led lighting myself, old gear needs the warm yellow glow! :leet:

    Anyway calibrating the amplifier section is easy. Measure the DC offset and ensure it is within specs, on some amps this can be adjusted while on others you need to replace some transistors to correct if it's too high. Then check and adjust the bias.

    Tuner alignment is a completely different kettle of fish. That requires specialised equipment and needs to be done professionally (although if the tuner is stable and sounds decent I'd not bother).
     
    Last edited: Nov 3, 2009
  2. itachi46

    itachi46 Member

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    well i will not use the tuner so i dont really care about that..

    and u have no idea how unaccessible those lights are to be replaced and how often they blow out >.< i totally understand why he went LED
     
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    aokman

    aokman Member

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    cheers :) yeah im going to leave the tuner if i can, it works fine anyway but i ordered all the caps it needs just incase... I also love the old lighting, unfortunately its not viable for this amp anymore as the lamp covers have become very brittle from the heat like every other 2275 and i dont want to put them through any more heat :(
     
  4. Asteroid

    Asteroid Member

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    You just need to know where to look! If they're blowing too often I'd imagine they're being run too hot, so check the voltage being applied to the lamps and check the globes are the correct rating.

    Sansui AU-217 & TU317:D

    Oh it's usually advisable not to replace the caps in the tuner section without having an alignment afterwards.
     
  5. itachi46

    itachi46 Member

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    and sry for the noobie-ness but whats a bias o.o i thought they only existed in tube amps (hence i never came across them >.<)
     
    Last edited: Nov 3, 2009
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    aokman

    aokman Member

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    got bored this afternoon and decided to get the annoying bit out of the way which is refinishing the faceplate....

    Sanded the scratches out of the face and blended it in with the existing finish - filed and refinished the bezel sides from where the amp has been smacked into things also :)

    heres a quick piccie of the results, ill get more details ones shortly :)

    expecting mr fedex with my caps tomorrow :)

    before:

    [​IMG]

    after:

    [​IMG]
     
  7. itachi46

    itachi46 Member

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    man i just opened my amp up to see how i'd LED the lights (the one that looks like fuses) where did you put your ac->dc converter? and what colours did you use to get a similair colour to the old one?
     
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    aokman

    aokman Member

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    im mounting the converter near one the power supply board on the chassis, im using blue leds for the main backlight also...

    Santa just dropped off his sack of capacitors for me and i got cracking with the tone board :)

    Heres a pic of how it went anyway, all the electrolytics are done and all the tantalums are done.

    [​IMG][​IMG]
     
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    aokman

    aokman Member

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    Todays work so far:

    P800 board has been stripped of caps and relay - washed the board down and removed PCB glue, replaced all caps with Panasonic FC series - replaced relay with new part and also replaced the insulator for the tranny :D

    [​IMG][​IMG][​IMG]

    [​IMG][​IMG][​IMG]
     
  10. itachi46

    itachi46 Member

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    hehe new caps seems so much smaller it looks.. weird >.<
     
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    aokman

    aokman Member

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    haha yup :) new technology caps can be over 100% smaller in some cases :)
     
  12. itachi46

    itachi46 Member

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    how bout the 2 massive 55v caps? are the new ones smaller too?
     
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    aokman

    aokman Member

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    im using Panasonic THA series caps :) 80v @ 15000uf - they are the same diameter and about 0.5cm shorter, you have to compromise on some specs to get caps with the same diameter for the holders. Even so these caps should be more than a match for what the old caps could do :)

    [​IMG][​IMG]
     
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    aokman

    aokman Member

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    Well final update for the weekend, spent most of the day on it today between running around grabbing little bits...

    I managed to strip it down removing both amp modules, old filter caps and the transformer. I cleaned up the main chassis while the area was clear as best as i could :)

    I repainted the transformer as i wasn't happy with the paint on the top of it, refitted it to the amp and resoldered all the wiring - also installed the new caps with ring terminals and cut down/drilled holes in the main coupling for the 2 caps to suit the new style connectors :)

    Overall its been a busy day, the transformer was more of a challenge than i thought it would be, ive never felt something so heavy before :D Trying to heat up big bits of metal with 2 soldering irons always makes for fun and games aswell :upset:

    [​IMG][​IMG][​IMG]

    [​IMG][​IMG][​IMG]

    [​IMG][​IMG]
     
  15. neoprint

    neoprint Member

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    What? They're taking up negative amounts of space now?

    Or was that a joke I didn't get...

    Anyway, looks good dude
     
  16. itachi46

    itachi46 Member

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    think he meant 50% ;)
     
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    aokman

    aokman Member

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    haha yeah my bad :D
     
  18. Xenolah

    Xenolah Member

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    Nice thread, I find this old gear fascinating. I recently recapped a Sony ES series amplifier, the build quality of some of this older equipment is excellent - the sound is great too! Good luck with the rebuild.
     
  19. THeX

    THeX Member

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    I was once lucky to be able to see a Denon, Marantz, Pioneer, Yamaha, Sony amps all at the same price ranges opened up. The build quality in the Sony ES amps are still very made to a very high standard - I was very impressed.
     
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    aokman

    aokman Member

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    Well time for an update :D

    i have now recapped every board and reassmbled the guts of the amp :)

    I have just been through and done the idle current, DC offset and DC supply calibrations.

    I ran the amplifier for an hour to warm up the components and let the caps settle in and adjusted to the following results:

    DC supply: 35v
    Idle current: 24.9mvdc both channels
    DC offset: 0.000v both channels

    [​IMG][​IMG][​IMG]

    [​IMG]

    getting a buzz through the speakers at the moment but its probably because the front is dismantled still i guess either that or its grounding as it goes away if i touch the chassis.

    The sound it is putting out so far is just astonishing, it has so much more depth than im used to, especially with instruments where you hear the entire action and not just the result

    More to come :D
     
    Last edited: Nov 13, 2009

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