Fender Passport PD-150 Service Manual - Passport
PASSPORT
®
PD-150
(This is the model name for warranty claims)
5
PCB EXCHANGE POLICY
Parts marked with a single asterisk (
*
) in the Part
Lists are not field replaceable. If a failure due to
one of these components is detected, please
contact the FMIC Customer Service Department to
order the complete PCB Assembly.
CIRCUIT DESCRIPTION
This section provides concise information about new
or unusual circuitry designs incorporated into this
amplifier model. The purpose is to aid the service
technician by providing insight into the design areas
most likely to become obstacles in troubleshooting.
Information is focused for its effective use while
maintaining the security of Fender® proprietary
information wherever possible.
The PD-150 consists of the following modules.
1. Mixer Section
2. Digital Reverb Section
3. Signal Processor Circuit and System EQ Circuit
4. Power Amplifier
5. Switch Mode Power Supply Unit (SMPSU)
The Mixer PCB module
The mixer section is mainly made up of operational
amplifiers as gain stages and therefore a technical
description will not be used here. Following is a ba-
sic circuit description to familiarize you with the
layout of the circuit.
The Mic/Line section is made up of 3 microphone /
line inputs each with a first stage preamplifier for
balanced or unbalanced inputs (locate on the mixer
board). Line inputs can operate as either balanced
or unbalanced if TRS or TR 1/4" jacks are used re-
spectively. Gain selection of 1dB/+30dB is made by
switching a different value resistor in the input
stage. At this point on channel one, the signal is
picked off for the VIP control ducking circuit made
up of U1B.
After the input stage there is one knob for contour
control, followed by an auto-pad level control where
the signal splits off into the rev/aux bus and main
signals. The main signals are then routed to a pan
circuit. Here the main signal is split between the left
and right channel signal bus. Channel three also
has an additional input via a pair of RCA connectors
where the signals are summed into mono which
may be used as an auxiliary audio signal input.
The stereo mixer section consists of a stereo pair
inputs with RCA and 1/4" stereo phone jack con-
nections. This circuit consists of an auto-pad level
control, low frequency and high frequency tone con-
trols, Rev/Aux send control and balance control with
signals feeding the left and right audio bus. The
audio bus is connected to three FETs that perform
ducking of the signals on the bus with the exception
of channel one which is the drive circuit for the VIP
ducking circuit. This function is provided by U1B.
Bus signals are buffered by U8A/B and drive the
tape output connections and drive the main left and
right master level control circuitry made up of
U9A/B. The Rev/Aux signals are buffered by U12B
and feed the mono aux send output. Main left and
right level controls are auto-pad configuration and
drive the speaker EQ circuitry made up of U10A/B.
Note: Channel 1 Mic/Line reverb function will be af-
fected by VIP control making announcements on
Channel 1 dry.
The mixer board also contains part of the signal
processor circuit and the system EQ circuit for the
power amplifier. These circuits are an integral part
of the power amplifier and appear after the return
signal path.
These circuits will all be discussed later in this doc-
ument.