Counter 700
for all Revox A700
LED 7-segment display, 5 digits
In 2011, while reviewing the documentation for the Studer A807 or Studer A810, I noticed that Studer generated the hysteresis of the light barrier using the luminous flux. When light hits the light barrier sensor, a larger current is supplied to the light source, making it even brighter.
This led to the first electronic counter for the Revox A700. On the A700, there is very little contrast between the cadmium-plated blade of the tape movement sensor and the aluminum front.For the sake of simplicity, the lighter aluminum front is also darkened.
The first digital counters were still four-digit and only displayed the correct value and time at a speed of 19 cm/sec. For speeds of 9.5 cm/sec and 38 cm/sec, conversions were necessary. This was very unsatisfactory when using a processor. Today, the counters are five-digit. The calculation of the played tape length and the correct display are instantaneous when switching the speed on the Revox A700..
The purpose of the counter is:
Similar to the old counter, counting the tape length and now displaying it in 5 digits using easy-to-read LED technology.
As a result you will receive:
A much more legible display of the current tape length. This, in turn, makes it easier for you to locate specific tape positions.
For each of the three speeds you will receive the appropriate belt length in hr. min. min. sec. sec.
All counter readings are retained even after the tape machine is switched off.
Another advantage is:
No slippage: The accuracy is better than with mechanical counters with belt drive, which always have slippage!
You will never need drive belts again, which have to be replaced at regular intervals with some effort (removing the front panels and removing the rear panel).
Description Counter 700
for all Revox A700
and Studer A67
White ads
We exclusively use the white 7-segment displays manufactured for us. This gives us, and you, a great deal of flexibility when it comes to choosing the color later. You can choose your color on-site, or even color combinations. White also looks very classy on the Revox A700 and complements the aluminum trim perfectly.
Filter foils
You decide how the display should look right there at home! As shown in the photo, you can also freely combine the colors. The green numbers would then represent the seconds display.
Red and white correspond to the colors of the analog counter.
Data retention
If "P-OFF" stands for power off, the data was recorded after the undervoltage was detected.
(turning off the Revox A700) is successfully saved. "P-OFF" is now displayed until the operating voltage finally collapses. The low-voltage detection is checked cyclically. If low voltage is detected, the display is blanked, and the values of the three speeds are saved to the internal EEPROM or internal flash. After the work is complete, "P-OFF" is written to the display.
Capstan Off
The internal wiring of the speed switches on the power strip prevents the "C-OFF" display. If the Revox A700 is used as a preamplifier or mixer, the capstan motor can be disabled by not selecting any of the speeds. If none of the speeds is selected, the device on the power strip will be fooled into thinking it's running at 19 cm/s. What a pity!
Revox A700
For the first 3 seconds, A700 is displayed. You should know that this is a Revox A700 tape machine! The checks and loading of the data take a while. No, not 3 seconds, but it would only be a brief flash, so we set the display to 3 seconds!
speed
For each of the three speeds of the Revox A700 tape machine, the corresponding played tape length is displayed in hours, minutes and seconds.
2 hours at 9.5 cm / sec. =
1 hour at 19 cm / sec. =
30 min. at 38 cm / sec.
Belt speed
Connector
Thanks to this small adapter board, no soldering is required. Simply remove the old counter, install the Z700 electronic counter into the Revox A700, disconnect the cable from the capstan control, plug in the adapter board, and plug the cable into the adapter board—that's it!
Removal of the analog counter
Caution! Always work on the devices without power!
Dismantling
Although the conversion is relatively simple, there are many steps to be taken, the sequence of which is self-explanatory.We supply all the necessary components for the required conversion. First, however, the Revox A700 must be disassembled. To do this, the pressure roller and the two deflection rollers of the tape tension scales must be removed.
Front panel
Now loosen the screws on the upper and lower front panels, and the screws on the control panel, remove the head cover, the frame, and the upper front panel. Now pull off all the control knobs, then remove the control panel and the lower front panel.
counter
The mechanical counter is now freely accessible and can be removed, also secured with two screws.
You can safely cut and remove the rubber drive belt. Even if you want to save it for later, that won't work. In a few years, the belt will be ruined!
back
To remove the back panel, 8 screws must be loosened.
It's perfectly sufficient if you can set the rear panel to the right a little bit aside. You only need to plug in the connector here!
Installation of the digital meter
Montage
The digital counter is mounted where the mechanical counter was once screwed in. To do this, screw in the two spacer bolts included in the delivery.
circuit board
The counter board is then screwed onto these spacers and aligned so that all five digit segments are visible through the Revox A700 control panel. Alignment of the photodiodes is not necessary.
Strands
Now guide the wires through the generous opening of the Revox A700 to the rear over the capstan control and turn the device over.
Capstan control
Tone motor control, or speed control with quartz control! The B77 should have had that too for its two speeds!
J1 is the right, 12-pin connector for the capstan control. Pins 1, 2, and 3 on J1 provide the signal for the set speed on the A700. Pin 5 carries the 24V supply voltage, and pin 9 carries the required ground.
First, disconnect connector J1 from the capstan control. Then, plug the adapter board 1.067.100.11 with the connections to the counter into the free connector J1.
Connection
and then plug the previously removed A700 connector back in – that's it, it really is that easy!
The plugs are coded, so they cannot be plugged in incorrectly or reversed polarity!
assembly
Reassembly is done in reverse order! Only connect the Revox A700 to the power supply after assembly.
Danger!
Always unplug the device before opening it! Electric shocks can be fatal.
If you have suffered an electric shock, consult a doctor. Ventricular fibrillation can lead to cardiac arrest even months later!
Counter Z700 in the shop
Here you can find our Z700 counter in our Premium-Hifi Shop:
