[QuadList] Rebuilding RCA TR-600s - Success

[Rob Lingelbach]

On Sep 10, 2009, at 4:39 PM, John Walko wrote:

> Rob:
>
> When first starting the tape, the tension arms have some minor  
> oscillation, but once the tape locks up, they remain pretty much  
> centered.

If I'm not mistaken, there's a feedback loop in lockup back to the  
arms and it was my first experience with the whole idea of Phase Lock  
Loop.  (vague recall could be wrong)

> The one issue I noticed is if the supply reel is full (just starting  
> playback) and the take up reel is empty, we have more tension  
> issues.  Spot reels are a lot easier to work with.

the less mass in consideration, the faster the feedback loop for lockup?
I remember with large reels and mass a lot of slewing, and then  
sometimes
the eventual drop of a loop and stop, but I don't think I ever broke a  
tape on a 600.

Sometime it would be interesting to recall the Kafkaesque times when  
after 12 hours of dubbing one would blow a hole in a master for which  
there was no protection copy...

> We are trying to match reel sizes as closely as possible…but are  
> having trouble because we don’t have a take up reel as large as a  
> one-hour supply reel.  We will need to get one.

and you're not even into the 90s yet :)

> We backed off slightly and are adjusting the tension to try to keep  
> the arms centered between the two stops.

there's an art to this, and there might have been some mods to  
introduce wider tolerances to the PLL circuit(s)...

There was an engineer at Unitel, Rex Chookolingo, whom I might be able  
to find who used to tune my TR600s.   He was on the TIG not long ago...

but I think there are also several already here who have the Knowledge.

>  Regarding maximizing the RF envelope, the video just seems to look  
> better when running in manual.

sounds right.


--  
Rob Lingelbach
rob at colorist.org









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