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By the way, to be clear, if your head assembly is properly jumpered and the
machine was using a properly jumpered head assembly when calibrated, the
switching is, normally, automatic.  But this is not guaranteed to be or to
have been the case.  And, if it isn't/wasn't, then even correctly-jumpered
assembly can trigger the wrong tension.  (e,g, calibrated with 1/2" assembly
but with jumper inexplicably missing or failed - then switch to 1/4"
assembly and have twice the wanted tension.)

If you have a 1/4" head assembly on the ATR-100, there should be no jumper
between holes 1 and A on the little circuit board.  If the assembly is 1/2",
it should have the jumper.  But this would have to have been the case during
tension calibration.  Probably best to check before a transfer session.  The
extender board is adequate, rather than tentelometer, in most cases.  Ymmv.




Andrew




On 6/15/12 8:41 PM, "Andrew Hamilton" <[log in to unmask]> wrote:

>      There is different varistor tuning required for 1/2 inch reels on the
> ATR-100 (than that which is... for 1/4").  When you calibrate the session
> tension, you aim for performance which favors one or the other width tape.
> This will cause twice the tension for 1/2" tape in forward and reverse
> modes.   If you use 1/4" reels with the machine calibrated for a 1/2"
> session, or vice versa, there will is the possibly of issues with packing
> and or cue-ability.
> 
>      The machine tries to keep constant tension on both sides of the
> pinch-rollerless capstan.  When I unwind a small reel (that is "tails out"),
> I use a matching size empty reel for (playback) "supply," just to make it
> simpler for the logic.  Might not matter, since it has to sample and
> resample the whole time, but I don't want to make it think too hard. (L;
> 
>      I tried using plastic, locking NAB adapters figuring that they would
> hold the reel more stable with the shaft rotation.   But this proved in some
> cases counter-productive.  Best action on my model was with the mash down
> holders, since they hold it down well, while still allowing "micro-slip"
> during the odd, momentary servo spasm.   Also, the alu reel hold downs are
> meant to conduct static to ground - at least that's what I've read.
> 
> 
> Andrew
> 
> 
> On 6/15/12 6:54 PM, "Goran Finnberg" <[log in to unmask]> wrote:
> 
>> Alex Kroh:
>> 
>>> I am using an ATR-102 that has very sensitive and
>>> unforgiving tensioning system and I have noticed
>>> that it doesn't handle too little weight very well.
>>> In fact, it won't play back 7'' reels without the
>>> added weight of the NAB adaptors. However, it does
>>> handle 5'' reels seemingly without compromise while
>>> using the NAB adaptor.
>> 
>> You are drawing the wrong conlusion here.
>> 
>> If there is any movement whatsoever between the reel and the motor shaft in
>> servo tension controlled tape machines such as Ampex ATR102 and the Studer
>> A820 then the servo will misbehave badly.
>> 
>> The mash down NAB adaptors used in the ATR102 will see to it that the
>> plastic reels are securely bonded to the reel motor mounting plate thus
>> there will be no movement between the motor shaft and the actual reel.
>> 
>> Thus reel weight has nothing at all to do with the observed misbehaving of
>> the ATR 102 servo system.
>> 

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