[QuadList] Rebuilding RCA TR-600s

[Chill315 at aol.com]

A couple of notes as to what to look for to solve your issues.  I have  not 
worked on this machine but the symptoms are universal.
 
The following is all speculation and conjecture.  Do not take it for  
gospel.  All legal statements etc. according to my Marx Brother  Lawyers.
 
First, the seeing of two syncs and bursts.  This is due to the timing  
difference between the machine and the house sync that you are using.  The  
house sync is being inserted back in according to what you said earlier.   All 
that needs to solve this is to find out how to get the H phase to align  with 
the house sync.  If you are in Regen mode, this will  disappear. 
 
The issue with the color bars changing color in the regen mode tells me  
that the machine is not gen-locking to the incoming black burst in that  mode. 
 A way to tell this is to trigger your scope from the outside house  burst 
and look at the output of the machine.  If the two signals are  moving, then 
you are not locked.  
 
You should do this to get the machine to be in time with the external  
black.  Show house burst on one channel of the scope and the output on  the 
other.  Then triggering off the house, get the two signals to line  up.
 
Reel tensions have to be done quickly.  Do not remove the reel motors  as 
there is a possibility of issues.  The reel turntable heights are set to  
SMPTE standards and not knowing how RCA did it you may have a minor issue.   
Ampex did it by putting shims under each bolt for the reel motor.  These  are 
very specific to each one so if you change, then it requires a way to get  
the height back to normal.  Possibly you could set up a measurement system  
to note the height of the table above the deck at all four bolt holes and 
then  replicate the numbers when the motor is replaced.  I have never had a 
motor  go bad in over 20 years.  The only time that I had to remove a motor was 
 when someone slammed a reel on and broke the pin that holds the turntable 
to the  shaft.  I was lucky that the Ampex person that built the deck had 
marked  the shim sizes on the back of the deck.
 
The issue of the black and white tape looking good and then the color tape  
going bad is interesting.  I do not know if the machine plays all three  
standards.  If so was the switch in the correct position?  Or does it  auto 
switch like the TR-70?  If the latter, then look at that  circuitry.  The auto 
EQ does not have a burst in low band black and white  so is shut off.  
Manual adjustment is required and it is sometimes not that  easy to see the 
banding in black and white.  Play back color bars and see  if the auto EQ is 
working.  If not, do the manual adjustments to get the  picture looking right.  
Then try the auto. It may be so far out that it can  not adjust.
 
The long lock up would also be an indication of the fact that the machine  
may be in the wrong standard.
 
Hope that helps.
 
Chris Hill
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