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C. GROUNDING OPTIONS
1. In certain installations, it may be desirable to separate the preamplifier
signal ground from the chassis and earth grounds. Noise inducing
ground loops can be broken while retaining the safety feature of the
grounded AC power cord. The 801 should not be operated with a
ground lift or "cheater" plug on the AC power cord. For 801
preamplifiers with serial #81031 and above, simply set the AUDIO
GND toggle switch on the rear panel of the power supply unit to the
desired setting (ISO or EARTH). To isolate the audio ground from the
chassis ground on 801 preamplifiers with serial #81030 and below use
the following procedure:
i. Unplug the power supply unit from AC power.
ii. With a No.2 phillips screwdriver, remove 9 #6 power supply top cover
screws and remove cover.
iii. Locate J9 and remove it. (see Figure 5)
iv. So that it will not be lost, push the jumper on to just one of the header
pins.
v. Replace the cover before applying power.
Figure 5. Power Supply Ground Jumper Location (SN#81030 and below)
