ATI Audio P1000-1 User Manual

Page 4

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The four inch copper strap which you are, of course, using for your station
ground is not going to fit around the #6 chassis ground screw on the MicroAmp
rear panel. Run strap to within a few inches of the chassis and jump to the
chassis ground with shield braid. Connect the tone arm ground lead to the same
point (or any other place that works better).

Plug cartridge leads into the phono jacks. Convention is white for left channel,
red or black for right channel.

Output wiring is indicated on the rear panel label. HI outputs are in phase with
each other and are in phase with the input signal. Transformer output
MicroAmps (1000-1) may have either HI or LO outputs grounded (but not both).

Single Ended Output MicroAmp (P100-3) has the Lo output internally grounded.
Do not ground the HI output as this shorts the output.

CAUTION

Balanced differential output MicroAmps (P1000-2) has active drivers for both HI
and LO output terminals. Do not ground either HI or LO terminals. To drive an
unbalanced (one side grounded) load connect it between HI and GND terminals
and let the LO terminal float. Two separate 600 ohm unbalanced loads can be
driven from each output without interaction by connecting one between HI and
GND and the other from LO to GND. The two loads thus driven will be out of
phase with each other. Individual grounds are provided for left and right outputs.

ADJUSTMENTS

The MicroAmp has sufficient gain and output capability to overdrive some
console inputs particularly those providing preamps for high level input channels.
Two o’clock on the level pot will provide +8 dBm for 0 VU (5 cm/sec) recording
level with typical cartridges providing 1 mv/cm/sec, 12 o’clock is approximately 0
dBm, 10 o’clock is approximately –10 dBm output. Operation with the MicroAmp
pot below 10 o’clock degrades noise performance and a fixed attenuator pad
should be placed between MicroAmp and output and console input to allow
operation around two o’clock.

MAINTENANCE NOTES

Power supply voltages are + and – 20 VDC nominal, dropping to +\- VDC under
full output. Maximum allowable voltages are +\- 22 VDC (limited by IC). If
zeners are replaced remove A1, A2, and A3 ICs and check output voltage before
plugging ICs back into the circuit. Remove power when inserting or removing
ICs.

This manual is related to the following products:

P1000-2