Tape tension for Revox B77


1.177.138 reel size and speed
If you want to evaluate the selected reel size and speed for the Revox B77 MKI, just like for the MKII, you need this tape tension board. With the Revox B77 MKI up to serial number 53.521, only the winding motor voltage is switched between 43 V and 55 V. The drive control of the first devices doesn't notice anything. There is no Tape Tension or Reel Size input on the deck controller. From serial number 53,522 to serial number 99,999, the reel size is evaluated by the drive control. In fact, our new Tape Tension circuit board is sufficient here to evaluate the speed as well.
Via solder bridges

the device version can be set

tin bridges

The version of the tape machine can be set via 14 tin bridges. We don't know which tape machine you have - this circuit board always fits!
14 tin bridges to set the version, revox-online
Jumper for super low speed for Revox B77 revox-online

Super Low Speed


Two bridges are set only at super low speed. Here the delay = 0 and still too slow! At all other speeds, four jumpers are always required!
Spannungsregler LM317, LM337 Revox B750 revox-online

Low Speed


Set tin bridges at the points marked in red, that's it. The delay is about 20 ms
Jumper setting for low speed, Revox B77, revox-online
Jumper setting for normal speed, Revox B77, revox-online

Standard


Here, too, 4 tin bridges are to be made. The delay is also hardly noticeable here and amounts to a few ms.
Spannungsregler LM317, LM337 Revox B750 revox-online

High Speed


There are also four bridges here. The maximum delay here is 200 milliseconds.
All this is described in detail in the supplied instructions. We can also manufacture the tin bridges here on site according to your specifications.
Jumper setting for high speed, Revox B77, revox-online
Tape tension PCB for all Revox B77 from revox-online

Evaluation


We at revox-online do the evaluation not only for the preliminary phase when starting up in Play or Record so that no loops form.
We set many more parameters with it. The recording delay, the duration of the electronic braking and other times are optimally adjusted for each speed!
Spannungsregler LM317, LM337 Revox B750 revox-online
connection

cabling


The speed signal must also be routed with the ground to the printed circuit board and, in the case of the B77 MKI up to serial number 53521, also the tape tension lines to the drive control. Since there is no pin in the machine for the S-Speed signal, soldering is required here. But the soldering points are very accessible!
Cable harness for the tape tension board, Revox B77, revox-online
two soldering points for the tape tension printed circuit board from revox-online

soldering

Both connections (green = S-SPEED, black = ground), which have to be soldered, are located on the power supply board on the outer plug, so that they are easily accessible! You will receive two cable ties and two screws M3 x 10 for fastening the board and the cable harness.

motor voltage

The 43Vac and 55Vac motor voltage connections can be plugged into the 2.8 x 0.8 flat connectors. In the older versions of the Revox B77, these are soldered. Then you can use the tabs as solder terminals and solder the connections there as well. It would also be possible to solder directly on the switch, but we advise against it!
Motor voltage connections Revox B77, revox-online
Large separation of the operating voltage, Tape Tension from revox-online

new tape tension board

We have designed the new tape tension circuit board 1.177.138-22 so that you can evaluate both the reel size and the current speed for tape machines of the first series (Revox B77 MK I up to serial number 99.999). Here, too, we have the greatest possible separation between the motor voltages and the operating voltage!
Tape Drive Control

The new drive control

You only need the new drive control for the Revox B77 MKI up to serial number 53521 so that you can evaluate both the selected speed and the spool size. With the Revox B77 MKI from serial number 53522 to 99999, the change with the speed evaluation is automatically effective due to the given hardware.
Brand new tape drive control PCB for Revox B77, revox-online
Tape tension connections to the new tape drive control for Revox B77, revox-online

Tape tension connection

We have adopted the labeling of the original drive controls (or and vio). Since the new electronics only queries the resistance value, the assignment is completely irrelevant. Our wiring harness is designed so that the orange wire is slightly longer. The colors of the strands can also vary. Orange can also be yellow, red or pink - depending on availability
the required strands!
Revox B750, neue Netzteilplatine von revox-online
brand new tape tension
1.177.138

for all Revox B77 can be found in our shop
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