QSC Audio Stereo Amplifier Q205 User Guide

Service Bulletin  
Title:  
Bulletin #:  
Models Affected: RMX 2450  
Q205 Lead Stress  
RMX0001  
Issue Date:  
May 15, 2002  
B
Bulletin Revision:  
Production Range: 01/2000–05/2002 (serial # 0100xxxxx–0502xxxxx)  
Description  
Driver transistor Q205 in the RMX 2450 may have been inserted into the circuit board with the leads too taut, causing one or  
more of them to break when subjected to vibration and strain caused by handling and other normal usage.  
This bulletin describes the procedure for removing the old transistor and replacing it with one whose leads have been  
prepped to provide a sufficient amount of strain relief. In this new revision of the bulletin, we also recommend removal of the  
circuit board mounting screws that are closest to transistors Q105 and Q205, even if the amplifiers transistor leads are not  
damaged, in order to allow the circuit board to flex more and thus put less stress on the transistor leads.  
Symptoms  
After the amplifier is turned on, channel 2s clip LED lights constantly or intermittently, regardless of signal.  
Instructions  
Replacing transistor Q205 requires removal of the amplifiers top cover and some minor disassembly. No circuit boards need  
to be removed.  
Tools and materials required:  
Soldering iron with fine tip (recommended range 25 to 60 W)  
Rosin-core solder (60/40 or 63/37 eutectic type)  
Long-nose pliers  
#1 and #2 Philips screwdrivers  
Small diagonal cutters  
Desoldering equipment or solder braid  
One prepped MJE15032 transistor (see Figure 1) per RMX 2450 amplifier  
Test equipment required:  
Oscilloscope  
2-ohm resistive load (rated for at least 1200 watts)  
AC ammeter  
Figure 1. Replacement  
MJE15032, with leads  
prepped for strain relief  
Variable AC transformere.g., Variac, Powerstat, etc.rated for 25A (120V) or 12A (230V). Make sure the amplifier and  
your AC supply are compatible.  
1 kHz audio sine wave generator  
Digital multimeter  
Trimpot adjustment tool (non-conductive)  
Procedure: Removing mounting screws  
1. Disconnect the amplifier from AC and wait at least 10 minutes for internal voltages to bleed down. Remove the screws  
(thirteen #8 screws on the sides and four #4 screws on the top) from the top cover of the chassis. Lift the rear edge of  
the cover until you can unhook the front edge from the chassis, then remove the cover.  
2. Locate transistor Q205. As viewed from the front of the amplifier, Q205 is attached to the left side of the heat sink and is  
the transistor nearest to the front faceplate.  
3. There is a multi-pin connector, J204, joining a ribbon cable to the circuit board next to Q205. Disconnect it from the  
board to provide better access to the transistor.  
4. Remove the mounting screw next to Q205 that fastens the circuit board to the chassis standoff. Also remove the screw  
next to Q105 on the other channel module. These screws will be left out when you reassemble the amplifier.  
RMX0001 Rev. B  
1
 

Radio Shack Cordless Telephone 43 3901 User Guide
Radio Shack Cordless Telephone 43 3905 User Guide
Razor Riding Toy 300001 SL User Guide
RCA CRT Television P61929 User Guide
RIDGID Saw 1224 A User Guide
Rival Rice Cooker FSD201 User Guide
Samsung All in One Printer SF 330 User Guide
Samsung Computer Drive SN 324 User Guide
Samsung Digital Camera Digimax 201 User Guide
Samsung DVD Player DVD 1080P7 User Guide