Installation Of Optional Input Transformers - Yamaha PM4000 Operating Manual

6.16 Installation of Optional Input
Transformers
The PM4000 standard input module is
equipped with a balanced, differential input
preamplifier for the XLR connector. That preamp,
along with some circuitry for the resistive attenu-
ation pads, is located on a small printed circuit
board that "piggy back" mounts to the module's
main circuit board. Refer to Figure 6-16A.
An optional transformer balancing option may
be installed by a Yamaha PM4000 dealer or a
qualified electronic service technician. The modi-
fication kit contains a replacement circuit board
for the original differential preamplifier, and a
separate input transformer. In order to install the
kit, the following steps must be performed.
1. Shut off the power to the console.
2. Remove the Monaural (Stereo) input modules
to be connected to input transformers.
3. Install the transformer onto the included
fitting with the nut as shown in Figure 6-16B.
4. Being careful with the wiring, unfasten Angle
H of the module by removing the two small
flat head screws and, the two small bind
screws.
Figure 6-16. Optional Input Transformer Installation
Page 6-17
5. From the inside of Angle H, insert the two
small M3 screws provided, and attach the
transformer fitting. (Figure 6-16C)
6. Reset Angle H to its original position.
7. Pass all the wiring through the slit in Angle
R .
8. Solder the transformer wiring to the new
input transformer board. (Figure 6-16D)
9. Remove the present input transformer board,
and replace with the new transformer board.
10. Reinstall the input module into the console
mainframe.
The above completes the procedures for installa-
tion of an input transformer. Check the Fader and
PAD signals to verify the installation. For a
Stereo input module, up to 2 input transformers
can be installed.
* Be careful that the wiring does not protrude
from the module. Damage could result when
the module is extracted.