50w 1987 bias pot - middle leg connection?

[Governator]

I’m about to commence my 50w build, and am not sure where or how the middle leg of the bias pot is connected on the board? All of the instructions and diagrams only show the two outside pin connections on the board but no mention of the middle leg. On the schematic it has the wiper of the pot (middle leg) connected to the right side pin that is connected to the 47k resistor on the board, I just can’t see if this is what is done underneath the pot. The last two amps I built were cathode bias so I’m not sure about this. Any help greatly appreciated, thanks.

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[martin manning]

The "ears" are the wiper connection.

[wpaulvogel]

This is how you solder it in. The ground is applied to the wiper terminals just like Martin described. Only one turret needs grounding. You bend the one leg terminal around and solder it to the capacitor lead. I bend the cap leads and feed them through the pot ears and the turret holes. Take needle nosed pliers and bend the ears 90 degrees so the pot lays across the top of the turrets.

[Governator]

The pot I have doesn’t have ears, it only has the three pins, pretty sure the middle one is the wiper. I’m guessing the middle pin needs to be connect to one of the other ones?

This is the one I have:

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[martin manning]

Yes the middle pin is the wiper, and it should be connected to one of the other pins (either one) to use it as a variable resistor. If you want to use that trimmer you’ll have to improvise. It’s a vertical mount type, which may not be as convenient to adjust. Besides the horizontal mounting, the one in the layout conveniently connects the positive leads of the two caps together.

[Governator]

I also have one of these ones below (25k), I could solder the middle pin to the bottom ground bus, solder the left pin to the capacitor lug (which is also ground) and solder the right pin to the 47k resistor led. Thoughts?

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[martin manning]

Sounds like a good plan.

[Governator]

Not as pretty as the ones with ears, but this will work, probably with a dab of hot glue where the telly blu-tac is to hold it in place. I can’t seem to get hold of the ones with ears in my country.

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