Remove all the wires going to the original ST-70 PC-3 driver CCA, as well as the RCA signal input sockets, the MONO/STEREO switch, and the two front octal sockets.

Carefully flip over your Stereo 70 and locate the four screws on the sides holding the chassis together. Remove these four screws and lift off the bottom plate from the rest of the unit.

Mar 13, 2021 · Those capacitors and resistors on the input jacks and stereo/mono switch is an old mod mostly associated with Frank Van Alstine. It is done to restrict the bandwidth of the audio signal to …

Install the slide switch that fits into the stereo/mono slot with 4-40 hardware. This switch will NOT BE USED and NOT CONNECTED to the ST-70 circuitry in any way but it fills the front rectangular slot to …

We’ll get to that in a moment, but first, remove the stereo-mono switch and the power switch. Again, if your amplifier was factory-wired, you will have to drill out the rivets used to mount these switches.

Two other modifications suggested by some restorers are replacing of the input/output jacks with gold-plated ones, and removal of the stereo/mono switch from the circuit.

Carefully flip over your Stereo 70 and locate the four screws on the sides holding the chassis together. Remove these four screws and lift off the bottom plate from the rest of the unit.

Using the Isolation & Elimination methodology, we would first place RCA shorting plugs at the input to your Stereo 70. If the hum is still present, it is safe to eliminate everything but the power amplifier …

Nov 9, 2024 · I replaced the sterwo/mono switch with a gain control, added the optional speaker binding posts so I could have both the 4 ohm and 8 ohm speaker taps connected.

Mar 10, 2010 · I've read over Bobs's instructions on how to remove the mono switch several times. Also the late Bill Thomas, who many of us knew, contributed virtually the same described process years …