You need to buy a couple of things. The first is a meter that reads DC current and the second is a 1/4" phono plug. To make things a little easier and safer, solder a wire to each of the tabs on the phone plug and strip the free ends of the wires enough so you can touch the meter leads to them. The tip of the 1/4" plug will be positive and the longer shank portion of the plug is negative. Warm up your amps. Plug the 1/4" phono plug into the jack at the top/rear of the amp. Set your meter to the scale where you can read 60 ma (miliamp) of DC current. Touch the red meter lead to the positive wire of the phono plug and the black meter lead to the negative wire of the phono plug. If the meter does not read 60 ma, then slightly loosen the jam nut at the top/rear of the amp...it has a screw in the middle of it. This is your bias adjustment pot and what you do is turn the screw ever so slightly one way or the other until you obtain the recommended 60 ma current setting. Gently re-tighten the jam nut on the adjustment pot, remove 1/4" phono plug and enjoy!
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