Pioneer Rt-707 Torque Measuring

[DRozell]

I was trying to measure the different torques on my RT-707 yesterday. In step 9.3 of the service manual, "Takeup Torque Adjustment at PLAY", I don't understand what direction figure 23 is telling me to pull the tension gauge for B' and C'. The manual states to "pull the tension gauge in the C' direction", which, if I follow the methodology used for A, B, C and D, means I should be pulling down on the left hand side of the reel. During forward playback the right hand reel is moving counterclockwise and the C' arrow is pointing down in the same direction as the reel is turning. What the heck I'm I missing? It did take me a while to figure out that there was back torque on the supply side reel during play (i.e. back tension torque) as that reel was working against the takeup reel to create tape tension so I'm probably missing something obvious.

 

[tapetech]

Just move/pull the scale in the opposite direction of the reel movement.

Doesn't matter if you pull Up, Down or Sideways.

So in FWD Play, pull scale sideways to the right since the reel spins to the left. String on top of hub

Or pull scale Up since the reel spins down, String on left side of hub

Or pull scale down since the reel spins up. string on right side

All the same

 

[Craig Skeet]

I'm struggling with this too. Does anyone know how to attach the gauge to the spool? Does it matters how far away from the centre of the reel it is attached?
I can't find any information on this.

 

[tapetech]

Does anyone know how to attach the gauge to the spool? Does it matters how far away from the centre of the reel it is attached

You wrap string ( or recording tape) around empty standard reel hub (not large diameter hub)
The distance matters and it is a standard empty reel hub size

For FWD back tension it is 70 to 80 grams

 

[Craig Skeet]

Does anyone know how to attach the gauge to the spool? Does it matters how far away from the centre of the reel it is attached

You wrap string ( or recording tape) around empty standard reel hub (not large diameter hub)
The distance matters and it is a standard empty reel hub size

For FWD back tension it is 70 to 80 grams

Many thanks for the reply,but I'm still not clear. If you wrap a string around the hub the hub will still be able to spin and when you pull it will just go to the centre top or bottom of the hub.
Do you attach the string to one of empty reel hub "spokes "?.
I'm sorry if this is a stupid question, but I'm still not clear and measuring this wrong will obviously mess things up.

 

[SCompRacer]

Yes you should anchor one end of string on the reel. Use a long string, like 30 inches. Make a small loop for spring scale hook. If the reel has an anchor pin, make a small loop on one end of string. If reel has spokes, tie one end of string around one and wrap string around hub. Reel with slots in hub, tie a knot on one end.

Teac specified a diameter for the reel hub in service manual when measuring tension. Math could be used to convert spring scale results for hubs of different diameter and they sometimes posted that formula in manual.

 

[Craig Skeet]

Yes you have to anchor one end of string on the reel. Use a long string, like 30 inches. Make a small loop for spring scale hook. If the reel has an anchor pin, make a small loop on one end of string. If reel has spokes, tie one end of string around one. Reel with slots, tie a knot on one end.


That's great. This is the first really clear answer I've found on this subject. Many thanks.

 

[tapetech]

 

[tapetech]

When you are threading tape, you need to attach the tape to the empty hub. Right? You do the exact same thing with the string. You can use tape instead of string if you want. Then put deck into play and slowly pull the spring gauge away from the deck to get the force reading on the scale (if you are measuring play mode tensions). For example for forward play back-tension you want the force on the scale to be 70g to 80g.