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Summary of Contents for AkitikA DYNACO STEREO 120
- Page 1 UPDATING THE DYNACO STEREO 120 SOLID STATE POWER AMPLIFIER REV B © 2013 AkitikA, LLC All rights reserved Revision 1.17 July 27, 2013 Page 1 of 32...
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Page 2: Table Of Contents
Table of Contents Table of Contents........................ 2 Table of Figures ........................3 Section 1: About this Manual ..................... 4 Who Should Attempt this Project? ................. 4 Tools You’ll Need......................4 Project Overview ......................5 Important Safety Notes ....................5 About Components ......................5 Recommended Solder ..................... -
Page 3: Table Of Figures
Test #3........................... 30 Test #4........................... 30 Resistor Color Code...................... 32 Table of Figures Figure 1-Location of the four screws that hold the cover to the base......... 6 Figure 2-Location diagram for cutting wires ..............8 Figure 3-After the Amplifier Modules have been removed..........9 Figure 4- Removal of components is completed .............. -
Page 4: Section 1: About This Manual
Who Should Attempt this Project? You can build this kit and update your Dynaco Stereo 120 if you can: 1. solder (using normal rosin core solder and a soldering iron). 2. use simple hand tools like screwdrivers, wire cutters, and pliers. -
Page 5: Project Overview
5. Wiring in the updated amplifier modules. Important Safety Notes By purchasing this kit, you have agreed to hold AkitikA, LLC harmless for any injuries you may receive in its assembly and/or use. To prevent injuries: • Wear safety glasses when soldering to prevent eye injuries. -
Page 6: Section 2: Saving The Stuff That Should Be Saved
Section 2: Saving the Stuff that Should Be Saved Opening the Amplifier 1. Make sure the amplifier is unplugged. If it was recently powered allow the amp to sit for one full minute before proceeding. 2. Remove the four screws along the outside edge of the bottom that hold the cover in place (see Figure 1). -
Page 7: Removing The Right Channel Module
5. Cut the black wire that connects to Q6’s emitter, near the emitter. There are two wires on the emitter...you need only cut the wire that runs to the black left speaker binding post. Save the LEFT module and mounting hardware. We will re-use the heat-sink and some other bits as described in “Salvaging the heat sinks from the amplifier modules”. -
Page 8: Figure 2-Location Diagram For Cutting Wires
Figure 2-Location diagram for cutting wires Page 8 of 32... -
Page 9: Figure 3-After The Amplifier Modules Have Been Removed
Figure 3-After the Amplifier Modules have been removed Page 9 of 32... -
Page 10: Removing C7 Right
Removing C7 RIGHT 1. Remove the 3 sets of #6 hardware that hold C7 RIGHT to the bottom of the chassis. 2. Unroll one foot of the wire that’s wrapped around C7 RIGHT and connects to the RIGHT RED Binding post. 3. -
Page 11: Figure 4- Removal Of Components Is Completed
Figure 4- Removal of components is completed Page 11 of 32... -
Page 12: Salvaging The Heat Sinks From The Amplifier Modules
Salvaging the Heat Sinks from the Amplifier Modules Figure 5- Separating heat sinks and circuit boards Remove the four numbered nuts, bolts, and standoffs. Cut the wires that connect the power transistors to the circuit board. Remove the four screws that hold the power transistors to the heat sink. -
Page 13: Test The Power Supply
Figure 6-Connecting a test load to the power supply Test the Power Supply 4. Make sure that neither the resistors nor their connections rest on the chassis. This is important. 5. Make sure that none of the other dangling wires is making contact with anything else. -
Page 14: There's No Voltage At All
This section details the process of building the amplifier module circuit boards. We start with an overview on this page. Begin by carefully emptying the contents of one of the envelopes marked “Akitika Stereo 120 Amp RevB Updatemydynaco” into a broad soup bowl, as shown in Figure 7. -
Page 15: Install The Resistors
Figure 8-Closeup of Completed Amplifier board (your big cap may look a bit different) Install the Resistors In general, you install the resistors by placing the body on the silk screen side of the board, and the leads through the indicated holes. Bend the leads over on the back of the board to keep the resistors from falling out until your solder them in place. - Page 16 Keep track of your progress by placing a check-mark in the done column as every resistor is installed. The resistor values can be checked with a meter, or by reading the color code . Orient the resistor with the fat brown band on the right, then you can read both the Color Code column and the resistor from left to right.
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Page 17: Install The Small Capacitors And The Diodes
Figure 10-Zero Ohm R22 installation detail Install the Small Capacitors and the Diodes Now we’ll install the following small capacitors: Designation Value Marking Done Done 220 pF 220 pF 47 pF Here’s what these three caps look like (not to scale): Next we install diodes D1, D4 and D5. -
Page 18: Last Capacitors And The Transistors
Next we install LEDs D2 and D3 (Light Emitting Diodes – the green light from these LEDs will be of medium brightness, and thus visible in a normally lighten room. Be careful! Light Emitting Diodes have a polarity, also! Read carefully to make sure you’re putting the diodes in the right way! The cathode of the LED is indicated by a bar (negative sign) molded into the package. -
Page 19: Winding The Output Inductor
Install the transistors. Spread the outside leads a bit to make it easier to insert them into the board. Orient the transistor so its body shape matches the silk-screen outline. Leave the top of the transistor about ½” off the board! The lead length prevents stress on the body and keeps the transistor safe from too much heat during the soldering operation. -
Page 20: Solder The Lm3886 Into The Board
Figure 12-Starting to wind the output inductor Figure 13-finishing step for the output inductor Solder the LM3886 into the Board This is the last step in stuffing the circuit board. By now, you are pretty good at soldering. Your skill will help you with this step. Just follow the instructions calmly and carefully, and you’ll do just fine. -
Page 21: Figure 14-Showing Method Of Attaching Brackets To The Pcb
b. The LM3886 body should sit at right angles to the plane of the board. If the result comes up a bit away from a right angle, don’t worry. The mounting system is compliant enough that this won’t be a problem. 5. -
Page 22: Final Inspection Of The Circuit Board
Figure 16-LM3886 installation step three, just the corner pins are soldered Figure 17-The LM3886 sits up off the board to avoid shorts between the front and back rows of pins. The body should be at right angles to the circuit board Final Inspection of the Circuit Board After you’ve taken a break, look over your completed circuit board(s) one more time. -
Page 23: Mounting The Updated Amplifier Board To The Heat Sink
3. polarity of C1 (minus sign away from the indicated plus sign on the silk screen). 4. polarity of C6 (minus sign away from the indicated plus sign on the silk screen). 5. polarity of C7 (minus sign close to the edge of the board). If you get one of these polarities wrong, there is a good chance that the amplifier won’t work, or there will be damage when you power it up. -
Page 24: Section 5: Wiring In The Updated Amplifier Modules
3. Assemble the LM3886 and circuit board to the heat-sink plate as shown in Figure 14, using the 6-32 hardware, just finger-tight. 4. Square up the assembly of the circuit board to the heat sink, and use the #6 screws and fender washers to fasten the brackets to the heatsink. -
Page 25: Revise The Power System
Figure 3 shows the way the wiring was. Figure 20 shows the way things will look at the completion of the next two sub-sections, Revise the Grounding System and Revise the Power System. 1. Remove the nut and bolt that hold the ground lug to the chassis. It is located between C12 and the transformer (Refer to Figure 3). -
Page 26: Complete The Ground System
Figure 20-Rewiring the Power and Half the Grounds Complete the Ground System Please refer to Figure 21. It shows how the completed wiring will look. 1. Locate the centrally located hole in the chassis nearest the input/output panel. It previously was used for an output capacitor mounting bracket. We will locate a star-ground lug in that hole, fastened with a 6-32 screw and nut. -
Page 27: Wiring The Outputs
a. Cut the second black-white twisted pair to a 5.5” length. b. Strip ¼” of insulation off both sides of the two wires. 4. Connect the black/white twisted pair to the Left channel input jack. a. Black wire to the shorter terminal (ground) b. -
Page 28: Connecting The Right Channel Amplifier Module
a. From the component side of the board, insert the left channel black wire through the left channel INGND eyelet and solder it on the solder side. b. From the component side of the board, insert the left channel white wire through the left channel INPUT eyelet and solder it on the solder side. -
Page 29: Making The Speaker Binding Posts User Friendly
14. Check your work. The following eyelets on the PCB should each have a wire: a. VCC (red wire of the red-black pair) b. PGND (black wire of the red-black pair) c. IGND (black wire of the black-white twisted pair) d. -
Page 30: Test #2
c. Feel the heat-sinks. There should be no appreciable heating. 6. In all but a very dark room, the LED soft glow should be invisible. If the LEDs glow brightly in a well lit room, you have probably mis-loaded some resistors. If this all goes well, (no smoke or excess heating) leave the power on and move on to Test #2. -
Page 31: Figure 22-Schematic Of Amplifier Module
Figure 22-Schematic of amplifier module Page 31 of 32... -
Page 32: Resistor Color Code
Resistor Color Code Figure 23-demonstrating the resistor color code Here’s an extreme close-up of a ¼ W metal film 20K (20,000) Ohm resistor, designated by the standard resistor color code. The colors map to numbers: Color Number Black Brown Orange Yellow Green Blue...
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