CR-620 noisy 2SC1917 .... modern equivalent ????

Discussion in 'Yamaha' started by Bert 1100, Apr 27, 2018.

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  1. Bert 1100

    Bert 1100 Super Member

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    EDIT: it turns out the 2SC1917 were fine, the culprit was TR671 / 672 (2SC1213, replaced with 2SC945)

    Hello Yamaha people !
    I've fully restored my nice CR-620, it's all working very nicely apart from a hiss in one channel.
    Volume does NOT affect the hiss, but the treble control does, as do all other tone controls and filters. The only transistors between volume and treble control are TR601 - 602 - 603 - 604.
    They are 2SC1917, there are a few in this receiver.
    What can I use as a modern substitution ? I searched AK and hardly found any reference to these transistors... so I need some help from you specialists :)
    I have some KSC945, KSC1845 and 2SC3503...are any a good candidate ?
    Thank you !
     
    Last edited: Apr 28, 2018

     

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  2. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Perfect sub for 2SC1917 are :
    - 2SC1570 Sanyo
    - 2SC2240 Toshiba
    - 2SC1844 Nec
    - 2SC1344 Hitachi
    - 2SC2634 Matsushita

    I will choose 2SC2240 more easy to find
     
  3. Bert 1100

    Bert 1100 Super Member

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    Isn't KSC1815 a sub for 2SC2240 ? And KSC1845 close enough then :D ?

    Merci beaucoup et coucou de la Suisse !
     
  4. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Hello !
    using a sub of a sub is not right
    using a 2SC2240 is easy don't look other TR , just double check EBC position !
     
  5. sregor

    sregor AK Subscriber Subscriber

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    Tone amp is not a "picky" circuit. KSC1845 will work fine. As noted above, verify EBC position.
     
  6. Bert 1100

    Bert 1100 Super Member

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    Thanks, I'll definitely check the pinout....
    2SC2240 is obsolete, are there any reliable sources left for them ?
    I'll go ahead and replace them with KSC1845 and report back.

    Clinic, I do understand that using a substitute of a substitute is not ideal....
     

     

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  7. Bert 1100

    Bert 1100 Super Member

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    So, I tried KSC1845 in place of the 2SC1917 (TR601 - 602 - 603 - 604), it worked, but the hiss stayed exactly as it was :(.
    Then I remembered a post by @ConradH in my CR-820 thread where he mentioned to first check TR671 / 672 when a CR-620 is noisy...and it turns out this was the case.
    They are 2SC1213, I replaced them with 2SC945...hiss gone :banana:
    One of them had an hfe of 120, the other one....30 !

    Thank you ! :music:
     

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