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Thread: Tascam TSR8 pinch roller rubber turns to gunk, replacement advice.

  1. #11
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    Yup that rubber conditioner is pure crap. Used it once years ago wnd it turned a perfectly roller to a gummy mess.
    Mild dish soap for cleaning has always worked for me.

  2. #12
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    Terrys re-furbished pinch roller has arrived back & is now working on my TSR-8!

    One minor problem on my machine, is that my channel 4 signal disappears when DBX is switched on, maybe a problem with the channel card which I'll have to check when time allows!

    Or has anyone got any idea of what causes this weird problem as all other channels work fine, DBX on or off!

  3. #13
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    I would:

    1. Re-seat amp cards and dbx cards (if applicable) and if that doesn't resolve the issue...
    2. Swap an amp card and see if the problem follows the card, and if the machine has separate dbx cards do a swap with those to see if the problem follows the card.

    I love a fresh roller from Terry!

  4. #14
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    I think the DBX is integrated. If reseating doesn't help, and the problem definitely moves with the card, I can probably spare one from my parts machine.

  5. #15
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    Thanks Guys! I seem to remember a few years it being the same problem & channel before, it started working fine after I left the machine on a few hours. Could be until Xmas before I get a real chance to look inside.

  6. #16
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    I think it's a different card to the record/playback card, maybe mounted from the other side of the machine? I may be talking rubbish as it's 20 years since I owned one.

    However sometimes just moving the cards around fixes these problems by breaking the oxide on the terminals.

    Alan.

  7. #17
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    Quote Originally Posted by witzendoz View Post
    I think it's a different card to the record/playback card, maybe mounted from the other side of the machine? I may be talking rubbish as it's 20 years since I owned one.
    However sometimes just moving the cards around fixes these problems by breaking the oxide on the terminals.
    Alan.
    Yeah, looking at the service manual this morning I can only see the 8 channel cards with no daughterboards. They are quite dense circuitry, and the DBX-related pots look like they're all down one end so I would assume the DBX is onboard.

  8. #18
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    Glad you got the roller replaced. I recently bought one for $80 on eBay to fix my TSR8. I'm just glad they still make these.

  9. #19
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    I swapped the channel cards around & the problem followed the card, looks like the DBX chip & encoder trimmers are by top side left (component side). I've re soldered the relay connections just in case, part link below.

    https://uk.farnell.com/omron-electro...-2a/dp/9949178

    Another relay, I'm not sure if this one is connected to the DBX area? I'll re-flow the solder connections on this one.

    SY-12W-K Fujitsu | Mouser United Kingdom


    The 3pin molex from the relay to the dbx section is fine. It would help If I could find my service manual!

    EDIT: DBX calibration, looks like I also need a function generator, AF oscillator & an attenuator, got everything else, it appears that the cards are calibrated outside the machine. I really need to get this channel card working as I calibrated the levels before I sold my alignment tape.
    Last edited by trancedental; 10-09-2018 at 02:05.

  10. #20
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    The DBX 1252 VCA looks like it has tarnished / rusty legs, I replaced a disintegrated resistor on this rec / playback PCB a few years back when it wasn't working, they are carbon film & there might be others out of spec? There seems to have been some fluid that got onto this card. I've tried to clean it up with isopropyl alcohol, to see if I can get the VCA back.

    So far no luck, here's the switching DBX circuit schematic.


    dbx-swich-schematic-png


    U6 DBX 1252 VCA does the noise reduction

    U10 is a 4way switch for DBX on/off, signal works fine when switched out.

    U3 A NEC 4570C opamp before above switch works but the output U3 B is situated just before the DBX 1252. Also U4A opamp 4570C takes the VCA signal afterwards before the switch circuit ends.

    So either the U3 / U4 opamps & / or DBX 1252 could be faulty / or any of the components in that section?
    Last edited by trancedental; 10-09-2018 at 17:39.

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