Power-on delayESV A700
für alle Revox A700
The power-on delay prevents the annoying power-on signal, the loud popping and banging, from being transmitted to the speakers and headphones during the Revox A700's power-on phase. Later versions of the Revox A700 feature the power-on delay as standard.
Additionally, the deflection of the pointer instruments is also significantly reduced. This protects the analog VU meters, which can easily fail due to the high deflection at power-up!
The delay time is about 4 - 6 seconds.
Revox A700 with ESV
Later versions of the Revox A700 were factory-installed with a power-on delay. This can be identified by the yellow relay (ITT A26xx) on the headphone amplifier. We have refurbished this circuit board with precision-fitted components (transistors, ICs with precision sockets, electrolytic capacitors with bypasses, and additional block capacitors on the ICs).
Replacement relay
We also offer a suitable, high-quality replacement for the ITT A 26xx 18 V relay. We can supply this replacement relay with 5 V, 12 V, 18 V, 24 V, 36 V, and 48 V. The switching capacity of the relay is 2 A, just like the original.
Installation ESV A700 for all Revox A700
Open Revox A700
As always! Unplug the power cord first!
230 V~ can be fatal!
The back panel must be removed. To do this, loosen eight Phillips screws, then tilt the back panel slightly forward and carefully remove it.
Audio unit
Technology that inspires! Even today, after more than 50 years! Where else can you find something like this?
base plate
Remove the front baseboard with 3 screws and the rear baseboard with 2 screws. Since the plastic baseboards often break, we also offer matching aluminum baseboards for the Revox A700.
Remove the mixing console
Remove the front panel using two screws. Remove the controls first, of course.
plug connection
Disconnect 3 connectors - this setup is ingenious!
This is what makes the difference to all other audio equipment manufacturers!
Disconnect from device
The entire audio unit is attached to the Revox A700 with four large Phillips screws. Loosen the screws and pull the audio unit out toward the front.
headphone amplifier
The headphone amplifier is attached to the connection board with just one screw!
Desolder C12 and C22
The new turn-on delay is soldered in place of the two capacitors. C12 and C22 are then connected to the turn-on delay plus two bypass capacitors!
Power supply
The supply voltage is connected to C1 UB and toC2 -UB tapped. We drill a hole in the circuit board and route the power supply wires through it. As you can see in the photo, there's enough space.For better location, the components (C1, C2, C8, C18 and IC2) have been labeled in red and are still without bypass capacitors!
ESV A700 installed
If the relays are visible from the outside (toward the RCA jacks on the Revox A700), the switch-on delay is correctly configured. The outputs will now be switched on with a delay!
In addition to the ESV A700, we also offer the counter and the new LED VU meter as well as bearings, repair and capacitor sets, lamps and much more.
quick shutdown
To minimize the popping noise when turning off the Revox A700, the A700's S-OFF signal is required (blue wire). The S-Off signal is tapped at pin 1 on J5a (headphone amplifier) or J6.
Delay headphone output
Disconnect the conductor track
The conductor tracks Y3-OUT-L, pin 2 of connector J5a and Y3-OUT-R, pin 3 of connector J5a are separated on the connection board of the Revox A700.
Whether you use a small drill or a sharp knife to cut the hole is up to you. The important thing is that the cut is complete!
connect with ESV
The same colored strands, ge/ge or vio/vio, are soldered over the previously made separations.
This also protects the headphone outputs and the VU meters from harmful switching on and off signals.
Both the VU meters, the speakers and your hearing will thank you.
Ready
It should look something like this for you too!We reserve the right to make technical changes (availability of components, improvements, etc.)!
Now reassemble the Revox A700 in reverse order. Before doing so, visually inspect all work and modifications!
The work of converting the Revox A700 is quicker than described here. However, the tape machine is very complex, and as always, you should know what you're doing!
ESV A700
in our shop
Here you can find the power-on delay for your Revox A700
