The Watkins tape echo presented was obtained from a guitarplayer using the device as just a preamp since the actual tape recording/playback circuitry did not work anymore. After some troubleshooting by Jacob a capacitor in the bias oscillator part was measured as faulty and replaced making the unit functional again.
A first view with the opened case revield a 2 replay head configuration that can be switched on/off per head. The tape mechanics is kept very simple as this unit was depicted as a low UMC (unit manufacturing cost) unit using only the minimal required components to make it to function. The tape path, as shown below, is a good example of this simplicity:
It's just straightforeward. Even the erase head was replaced by a simple magnet construct saving penny's:
and the printed circuit board was based on a more sofisticated model. It was re-used here so the extra valve position was just bypassed on the board.the quality of the board was well below par and would not been accepted by any QA department!
and, as the icing on the pudding, the device is just with two ECC83 valves a minimalistic approach to make money!
The fingerprint shows that both heads are on equal distance:
Last but not least a schematic diagram of the electronics:
-Piet
