Table Of Contents; Table Of Figures - DYNACO PAT-4 Assembly Manual

Table of Contents

Table of Contents ................................................................................................................ 2
Table of Figures .................................................................................................................. 2
Section 1: About This Manual ............................................................................................ 3
Who Should Attempt these Projects? ............................................................................. 3
Tools You'll Need........................................................................................................... 3
Project Overview ............................................................................................................ 4
Line Amp Distortion Reducer ..................................................................................... 4
Tone Control Switch ................................................................................................... 4
Important Safety Notes ................................................................................................... 4
Section 2: Line Amp Distortion Reducer............................................................................ 5
Line Amp Characteristics ........................................................................................... 5
How the Distortion Reduction Works......................................................................... 5
The Modification in a Nutshell ................................................................................... 5
Preparing to Remove the Circuit Boards .................................................................... 5
Modifying the Left Channel Circuit board ................................................................. 6
Modifying the Right Channel Circuit board ............................................................... 9
Inspection and Reassembly ......................................................................................... 9
Section 3: Tone Control Switch ........................................................................................ 10
Before You Begin ......................................................................................................... 10
Pre-wiring the Tone Control Switch ............................................................................. 10
Optional Gain Reducing Resistors ................................................................................ 13
Disassembling the PAT-4 Preamp ................................................................................ 13
Removing the HI FILTER switch. ............................................................................ 14
Mounting the tone control switch ............................................................................. 14
Wiring in the tone control switch.............................................................................. 14
Installing the Treble No-Click Resistors ................................................................... 16
Reassemble the PAT-4 .............................................................................................. 16
Using the Tone Control Switch..................................................................................... 17
Pops and Clicks ......................................................................................................... 17
Gain Trim Resistors ...................................................................................................... 18
Schematic .................................................................................................................. 19
Appendix: The Toothpick Trick ................................................................................... 20

Table of Figures

Figure 1-applying thermal compound and installing the heat sink ..................................... 7
Figure 2-New transistor with heatsink installed on PCB .................................................... 8
Figure 3-MPSW45A Pinout ................................................................................................ 8
Figure 4-circuit board as seen from solder side. The modification replaces Q4 ................ 8
Figure 5-Switch Wiring Diagram. The gray dashed lines indicated relations between
poles (center terminals) and throws (outer terminals). These gray lines are not on the
actual switch. The gain resistors are optional, and not included with the kit ................... 12
Figure 6-Installing the treble no-click resistors on eyelets 16, 17, and 18 ....................... 16
Figure 7-Tone control switch installed and wired to bass control, treble control and PCB's
(green wires called out in the assembly directions are blue in the pictures above). ......... 18
Figure 8-Schematic of the preamp high level stage showing the addition of the tone
control switch .................................................................................................................... 19
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