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Thread: 2340sx doenst erase fully

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    2340sx doenst erase fully

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    I have been doing some tape transfer tests on my 2340SX which has not seen use in a while.
    I am finding that track 3 does not fully erase the old signal on the tape...I can hear the old signal faintly in the space between songs and even under very quiet passages. Tracks 2 and 4 do not have any belled, while track 1 has a barely discernable bleed. Track 3 is more noticeable.
    If I hit record with no input signal on a pre-recorded tape,, 2 +4 are clean erased, 1 is very faint, and 3 has noticable old music bleed.

    Is this fixable by a bias adjustment or somethig of that sort?
    How would I do this. I do NOT have the manual on this machine

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    Bump????

    Any help here??

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    Hi Technoplayer,

    Sometimes this CAN be solved by biasing but it could be something else. I'm no expert on it really but my 3340 I just got had a similar problem and has been almost completely fixed by calibrating everything up to spec. I also ran into a problem once with my 38 that had this same issue on one track and I fixed it completely by tweaking the bias screw. The one you're not supposed to mess with not the one that is used when you're setting the deck up. But all these decks are different. I have a 2340sx but I haven't really looked to closely at the calibration set up on it Another thing can be the tape. I know I've had old tape on one of my decks once that wouldn't erase. The tape I was using was Maxell when that happened.
    "He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people, and eat out their substance."

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    Thanks Steve.
    I am using Maxell UD35 tape exclusively, and I ran the same reel on several other machine without any problem of this sort, so I'm, thinkin it the 2340's problem.

    I have not tried to adjust anything yet, and not sure where to start. Any guide as to where I could find the info on how to adjust the bias (either the one I am supposed to or the one im NOT supposed to)

    Thnkas for any guidance.

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    Technoplayer, Have you done any calibrating before? It's a little bit of an investment to get everything but it's worth it. You can get the manual from Tascam or ebay and the tape from here http://home.flash.net/~mrltapes/ The tape is #21T104 7.5 ips, IEC2, 200nWb

    I have the manual but I don't have a scanner to show you where it is and even then I wouldn't want to misguide you. If you have any specific questions feel free to pm me and I'll look it up for you.
    "He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people, and eat out their substance."

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    No, I have not done calibration. I do have an o'scope and and a nice DVM, so at least that should get me started. Any other test gear needed? I suppose I need to get a calibration tape. I appreciate the help. It may be a bit before I get to this...the day job needs the priority right now

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    Quote Originally Posted by technoplayer View Post
    No, I have not done calibration. I do have an o'scope and and a nice DVM, so at least that should get me started. Any other test gear needed? I suppose I need to get a calibration tape. I appreciate the help. It may be a bit before I get to this...the day job needs the priority right now
    If you have the VM then all else you really need is the MRL tape and the manual. You don't necessarily need the O'scope unless you want to check azimuth. Which might not be a bad idea though.
    "He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people, and eat out their substance."

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    Quote Originally Posted by technoplayer View Post
    If I hit record with no input signal on a pre-recorded tape,, 2 +4 are clean erased, 1 is very faint, and 3 has noticable old music bleed.
    pre-recorded tape? Is this pre-recorded tape recorded on
    this 2340SX machine or on some other machine?
    Knowledge is calculable, Ignorance has no limits.
    Dr ZEE
    MZE | Dr ZEE WORKSHOP

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    Several tracks recorded on my RT-707, and several tracks recorded on the 2340.

    >>>I do not understand what the MRL tape does for me. The problem seems to be a record bias (erase head??) issue. The MRL is for calibrating playback, correct? Or is the intent to play the MRL on one track while recording its reference signal on another track??

    To re-state the perceived problem:

    The tape has music on it previously recorded and played back on another machine.
    >>When i record over the music with other music, I can still hear a portion of the orignal song on one track.

    >>When I record over the tape with no input siganl at all, all tracks go silent except for one, which still retians some artifact music information.

    So it seems like the erase head is not applying proper bias to erase the tape.

    Is there not just a "reference" votage that i can adjust the erase bias for??

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    Quote Originally Posted by technoplayer View Post

    Is there not just a "reference" votage that i can adjust the erase bias for??
    Nop.
    There's nothing to "adjust" in respect to erase head on those machines.
    There's one single Bias "Power Station" for all and it serves erase heads 'directly' (through mechanical switch and through relay switch to be more specific, and it may be a good idea to check those, maybe dirty/oxy-rusty, you know).
    I've made a simplified diagram (see attached pic).
    You can adjust Record Bias for each Bias Switch Position by mean of vary-caps for each channel. In "the book" it is recommended to check/adjust Bias Traps first (not sure why). You can assume that yours are trapping just fine
    Also the assumption is that you get to the point of BIAS adjustment after you went through Play Back / Heads / Record aligment (again, that is by the book). If you assume that there's no need or no issues anywhere there, or if you simply don't care, then you can try to tweak Record Bias.
    You don't need MRL tape to adjust Record Bias level.
    The procedure in general is: Use the fresh tape you want to use for recording, set the deck in record for the channel you are tweaking, set monitor switch to "TAPE" position , select the BIAS switch position 1 or 2 (depending on which one you going to adjust, the switch simply selects one of two adjustable capacitors).
    You neet test tone Oscillator (source of steady signal, that is) to send to LINE input.
    The frequency may vary (it depends), the level of the signal plus the input / output level knobs position need to give you "good reading" on the VU-meter.
    In TEAC manual that I have it's 400Hz (-8dBm at input and at so-called speacified Input and Output level, which both are at knobs position pointing around "2 o'clock" or so).
    So you start recording that signal and monitoring the VU-meter. Then you turn the Adjustable Cap to find the point where you get the highest reading on the meter - the Peak, and then from that point you turn the cap slightly more until the level drops a"bit".
    How much to drop? That's a good question ...heh heh.
    In the TEAC-book, they say - 0.5dB.
    Different cook books, different meals - different stuff.

    If you want to tweak by the book, you gotta get the book. And the book will tell you what else do you need to get so you can do it by the book

    To get to the tweaking "Pod" - you need to remove bottom panel. I believe you will see sticker diagram on the inside of that panel showing different models and tweaking spots locations.
    But, seriously, you better at least get the manual and read it one time

    I am not sure if Rec Bias tweaking will fix your "problem" though. But I just can't know.

    One thing you may want to try, though, before anything else.
    Take fresh tape. Record all 4 channels something using THIS machine. Than erase and check if you still have exact the same "problem"

    here's diagram:
    Attached Thumbnails Attached Thumbnails teac_rec_bias_simplified_diagram-gif  
    Knowledge is calculable, Ignorance has no limits.
    Dr ZEE
    MZE | Dr ZEE WORKSHOP

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