Help required: how to run a cassette deck from a bench psu?

Discussion in 'The Projects Forum' started by illuminate, Apr 30, 2013.

  1. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    Hi,

    I want to run a Tascam 112MkII pro audio cassette deck from a precision linear bench psu (not yet purchased) to undertake a scientific task, but don't know how it could be connected. Can anyone advise me?

    I have two groups of wires coming off the pcb upon which the transformer sits. One is labelled "to Cont M PCB" (5 wires) and the other "to Main PCB" (4 wires).
     
  2. BMorse

    Senior Member

    Sep 26, 2009
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    really clear pictures of these boards would help a lot, at this point we can only assume.
     
  3. RayInMS

    Member

    Dec 12, 2012
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    That unit requires 120V AC. Is the unit not in the case?

    http://tascam.com/content/downloads/products/322/112mkII-TechDoc.pdf
     
  4. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    Maybe I am a little premature - I haven't got photos at the moment as I am awaiting delivery of the unit.

    I was hoping to upload the Service Manual but the file size is too big, and the zip size is no smaller.

    Page 1/11 shows the power supply arrangements.

    I will try to think of something else.
     
    Last edited: Apr 30, 2013
  5. illuminate

    Thread Starter New Member

    Apr 30, 2013
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  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    Why do you want to this? This look like a pro unit. So it should have a good power supply inside. I might be wrong here. But perhaps using a good sound card on a PC is a better option
     
  7. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    Here is a jpg screenshot of the power schematic.
     
  8. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    Thank you for your reply.

    The normal power supply generates a line frequency magnetic field that radiates into the unit's playback head and circuitry, which is what I want to avoid.
     
  9. t06afre

    AAC Fanatic!

    May 11, 2009
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    You can get transformers that convert 230 volt to 120 volt or the other way. I am quite sure your school have some. If not they are not so expensive for then you do not need much power. Like in a cassette deck
     
  10. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    I think you have misunderstood - this is not a school project.
     
    Last edited: Apr 30, 2013
  11. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Looking at the diagram it supplies AC to the main pcb for some reason, so running it from a DC supply is of no use, why dont you remove the transformer and place it external if its buzzing?
     
  12. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    I know that it can be done as there is a company who adapts the 122 model in the way that I am attempting.

    As I said initially, I am engaged in a scientific project and require the enhanced performance of a low noise and ripple linear DC supply.
     
  13. RayInMS

    Member

    Dec 12, 2012
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    Have you contacted this company? If they know how to do it, ask them or buy their technology. I'm a super-noob but I can tell you that what you want to accomplish will be pretty difficult (and seems counterintuitive me).

    Good luck with your experiment.
     
  14. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    It would be indiscreet to ask the company to reveal their design technology, and their modified deck retails at $5950.

    I bought mine at a fraction of that amount. If I can work out how to run it off a high end PSU I will have saved a lot of money.
     
  15. RayInMS

    Member

    Dec 12, 2012
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    There appears to be a DIP switch in your schematic that allows operation from 230v. Have you tried that?
     
  16. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    The internal circuit voltages are the same for all the line voltage varients - be it US, Euro or UK, so if I bypass the standard transformer it will not matter. The AC line voltage ends at the PSU.
     
  17. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    Here is a copy of the Tascam 112Mkii power supply schematic.

    As far as I can identify, there are two outputs +12VDC and -26VDC, but I have no idea what voltages "F" and "P Down" are, or indeed what they represent.
     
  18. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Ususaly F is an AC voltage used for a filament.
    Is there a tube (valve) in the recorder?
    It could also be for a VFD display.

    Bertus
     
  19. illuminate

    Thread Starter New Member

    Apr 30, 2013
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    I am afraid that I do not know.
     
  20. bertus

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    Apr 5, 2008
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