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Electronics Reverse cassette-to-3.5mm?

Discussion in 'Modding' started by Firehed, 29 Jul 2006.

  1. Firehed

    Firehed Why not? I own a domain to match.

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    Disclaimer - if you're familiar with the workings of a cassette adaptor, skip the story and head to the bottom...

    I manged to get an old cd/cassette/radio setup ripped apart (Sharp CMS-C333), since the CD changer in it was busted. I decided that I'm going to try salvaging the FM tuner, which is fine at the moment, but wanted to try converting the dual-cassette deck into a 3.5mm jack so that I can use the unit as a speaker system for my PC (going into a mame cabinet hopefully, or else I'd just use normal speakers).

    So, I just went in head-first and kind of guessed at the wiring. The cassette unit had three little wire harnesses. One 8-pin harness went to the shared motor unit. The other two each went to the cassette-reading heads (one was a five-wire thing, two of them went to a recording head, the other was three-wire straight to the other head).

    So after disconnecting one cassette head, I managed to dig up a tape and test it in the other one, with the power harness connected as well, and it was fine. Tried the other as well, just to confirm things, and it also worked. Pretty much confirmed for me that the pink/black/white wiring was indeed a line-in type thing.

    Here comes the smart part- chop off the little plug bit, and solder it to a 3.5mm jack. Great in theory, not so much in practice. Apparently the heads put out a far lower signal strength than a line-out jack :worried: Long story short, the adaptor I made is worthless due to the signal strength difference. Anything above a volume level above 1px wide on my iPod's display from the headphone jack (tried the line-out on the dock, which is WAY above that level) and it distorts to insanity, and at about twenty times the volume level it should be.


    Anyways, the question is this - how can I convert that cassette-head-in plug into something useful by a computer/MP3 player/etc? I came up with the idea of just using one of those car cassette adaptors in the working tape deck... AFTER I cut off the plugs :wallbash: (both of them! :wallbash::wallbash: and they're incredibly painful to solder to when I have decent-length leads to work with) In any case that would have been far less than ideal, as I'd rather not waste the space, but it should have worked. Would it be as simple as working a resistor into the loop, and if so, what size? Google is turning up neither information nor products, and I haven't found a cheap amp that I could use in place of this makeshift setup either.
     
  2. Pal_Mal

    Pal_Mal New Member

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    I did a similar thing with an old stereo but rather than take the route you took I found the output of the cdplayer inside the stereo and cut the wires there. If you look inside the stereo there should be one main link ( or maybe 2) between the main AMP / radio PCB and the CD player. If your Lucky the PCB will have ledgers on it telling you which wire is which , you want to try and find L R and G . If they are not written on the PCB you might be lucky trying to follow the PCB tracks back to the main Amp on the PCB. This output from the CD player is the same as a line in. It's worked great for me ofr usingt my laptop.

    hope this is off some help
     
  3. ConKbot of Doom

    ConKbot of Doom New Member

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    you could do a simple voltage divider to reduce the signal or just use trimmer pots to make it adjustable. But it would be more desireable to find a location where you can put the signal in at line level, rather then attenuating it then amplifying it again.

    Where do the leads/tracks from the pickup head go? what chip? if your lucky it might just be an indepenant amp that you could bypass.
     
  4. Firehed

    Firehed Why not? I own a domain to match.

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    No idea where everything goes, but the CD signal trick worked perfectly. I just needed to figure out what pin was what (and the figure out which bit of the jack went to what, which took much more googling than it should have), and plug it in. Hopefully the CD changer circuitry doesn't freak out too badly with nothing else connected. But it's tested and working fine.

    Simple fix for a complex problem. Much thanks Pal_Mal :)

    Now off to get fresh air... *solder fumes*
     

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