Title: DSP-4 DC Converter Update
Bulletin #:
Models Affected: DSP-4 Bulletin Revision: A
Production Range: 04/2002-10/2002 (serial# 0402xxxxx–1002xxxxx)
DSP0004 Issue Date: October 25, 2002
Service Bulletin
Description
Early production DSP-4’s were manufactured with the incorrect DC/DC converter causing the surrounding components to weaken. Also
in these units, the HD15 connector was not sufficiently grounded to the chassis. To correct this a spacer needs to be inserted between
the connector and the PCB to raise the HD15 connector to the chassis. With the help of the EMI shield that's placed on top of the HD15,
a solid grounding connection is made between the HD15 and the chassis.
Symptoms
The DSP-4 does not turn on; the blue power LED does not light. This symptom may occur when the DSP-4 is used with an external
power supply. Alternatively, the DSP-4 produces heavily distorted sound through the audio outputs. This symptom may occur when the
DSP-4 is used with a QSC DataPort amplifier that supplies power to the module. The DSP-4 may exhibit grounding problems when the
module is running.
Instructions
Tools and materials required:
Soldering iron with fine tip (recommended range 25 to 60 W)
Desoldering station
Rosin-core solder (diameter .015 eutectic type recommended) and flux
#2 Philips screwdriver
Small boxes or compartments (to keep assorted screws during disassembly)
Tweezers
PC running Signal Manager
Oscilloscope
Location Number QSC Part Number Description
U6 IC-0000225-30 LT1617ES5 (LTKF)
D5 & D7 QD-000190-30 40V 3A Schottky SMT
C32,C33 & C35 CA-610008-30 10uF 20V tantalum
J5 PL-000194-00 Spacer, HD15 Connector
NA NA WP-000411-01 Board ID Label
Table 1. Required parts.
Procedure: Updating the DC converter and surrounding components
CAUTION: Take appropriate anti-static precautions to guard against electrostatic discharge (ESD).
1. Disconnect DSP-4 from AC and wait at least 10 minutes for internal voltages to bleed down.
2. Remove all fourteen fasteners on the front panel of the DSP-4. Turn the DSP on its side and remove the other two fasteners, then
flip the DSP over (Data Port receptacle side) and remove the remaining fasteners. Note that there are four different sizes of
screws.
3. Gently pull the chassis apart and remove the PCB boards.
4. Separate the two PCB boards and locate the board with QSC part# WP-000411-00.
5. With your soldering iron and tweezers, carefully remove U6, D5, D7, C32, C33 and C35. If you find the parts difficult to remove, try
adding new solder to the pads for better heat flow. Use the tweezers to delicately lift the part while touching the pad with the
soldering iron. Refer to Figure 1 and Figure 2 for the location of the parts to be removed.
6. Use a desoldering tool or desoldering braid to remove excess solder from the solder pads.
7. Install the new components using the soldering iron and tweezers. Refer to Table 1 for correct part numbers.
8. With your soldering iron, carefully remove C17, C21, C25 and C43. Refer to figure 1 and figure 2 for the locations of these
capacitors. There will be no parts soldered in the place of these capacitors.
9. Use a desoldering tool or desoldering braid to remove any remaining residual solder from the solder pads.
10. With your desoldering tool, remove J5. Refer to Figure 1 for the location of this HD15 connector.
11. Install the spacer between J5 and the PCB. Refer to Table 1 for the correct part number.
Replace
Remove
Replace
Remove
Replace
Figure 1. Top Layer.
Remove
D7
Remove
Replace
Figure 2. Bottom Layer.
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