oscillator board
for all Revox B77

1,177,235 new development
In fact, we changed the circuit a bit!
At revox-online, we didn't want the relays to be switched on via the record LEDs on the front panel. The relays are now switched on via additional transistors. This means that 2x 220µF electrolytic capacitors can be omitted.
We rewind the oscillator coil and it is the most expensive component of all Studer Revox B77 audio cards.
the technique
the circuit

relay wiring


By changing the base circuit of the transistors, the electrolytic capacitors C 13 and C 14 can be omitted. Two additional LEDs LED 1 and LED 2 indicate on the printed circuit board that the relays are switched on. There are no bypass capacitors here. Why?
neue Relaisschaltung der Oszillatorplatine für Revox B77 von revox-online
Parallelschaltung der Einschalttransisitoren des Oszillators Revox B77, revox-online

turn-on transistor


Two switch-on transistors connected in parallel supply the oscillator with the necessary current. The series resistor is split here into R 15 and R 16 and is used at the same time for forced adjustment. This means that the power is evenly distributed to both transistors and series resistors. Thus, the power loss of the SMD components is small enough!

oscillator coil

The new coil no longer has an alignment pin! On the one hand, the coils with an adjustment pin are very difficult to obtain and then the coils are only suitable up to 100 kHz! But we need 150 kHz. The new circuit boards only have tin jumpers for adjustment! Whether we will continue to use the setting, we do not know yet!
Oszillatorspule ohne Abgleich für Revox B77 von revox-online
Schaltplan Oszillatorplatine Revox B77 revox-online

circuit

Apart from the small things mentioned, the circuit has remained Revox. Must also fit the tape machine. Instead of a spear converter, a freely oscillating oscillator could have been used here, which then controls the transformer, but why?

the new board


similar to that of the old circuit. The relays are more up-to-date, the position of the plugs of the sockets and the trimmers are specified. The jumpers that make the printed circuit board usable for all Revox B77s have moved to the solder side as tin bridges.
neue Input-Platine für Revox B77 von revox-online
Studer Revox B77, revox-online

adjustment


You cannot avoid an adjustment after replacing the oscillator board and it is absolutely necessary. The bias setting is a prerequisite for calibrating the Studer Revox B77!

ATTENTION! Never lay the tape machine on its front!

Oscillator board from revox-online

We have only changed small things, fine-tuning the frequency is no longer possible, but not necessary. It doesn't matter at all whether the oscillator oscillates at 145 kHz or 155 kHz!

if you want the best!

brand new oscillator-PCB
1,177,235
for all Revox B77 can be found in our shop
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