HP8640B Signal Generator
I acquired a very rough example of an HP8640B for £45 hoping to use it. Aluminium corrosion has cleaned up except for the attenuator knob. Both that and the main tuning knob need a proper Allen Key as none of mine fit. It seems to be something like 1.7mm across the flats? I managed to remove all the other knobs (with difficulty) using a key approx 1.27mm AF.
There are several faults, most concerned with stiffness of switches etc but one obvious problem is the main tuning control only rotates a revolution or so. One end appears to lock but the other is squishy. Is this a common fault? I notice a few early threads so hopefully someone can point to an easy fix? Possibly someone turned the knob too far?
I also need to fix a broken catch on the AM/FM switch which looks removeable and a seized RF on/off switch?
What's the best way of restoring a smooth finish to the exposed alumium parts.. emery cloth and oil?
The main question though... No sign anywhere of the mains voltage requirement. Is it 230/240 volts ?? And.. it was sold as dead but the mains fuse is OK and I see about 20 ohms into the mains terminals when the on/off switch is pressed.
Allan G3PIY
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