Related Manuals for DYNACO STEREO 120
Summary of Contents for DYNACO STEREO 120
- Page 1 UPDATING THE DYNACO STEREO 120 SOLID STATE POWER AMPLIFIER: SUPER HEATSINK VERSION © 2011 AkitikA, LLC All rights reserved Revision 1.12: October 20, 2011 Page 1 of 32...
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Page 2: Table Of Contents
Tools You’ll Need......................4 Project Overview ......................5 Important Safety Notes ....................5 Section 2: Checking the Stereo 120 Power Supply ............6 Opening the Amplifier ....................6 Check the Power Supply Voltages.................. 6 Section 3: Saving the Stuff that Should Be Saved .............. 7 Cutting the wires on the old amplifier modules.............. -
Page 3: Table Of Figures
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 ..............9 Figure 3-After the Amplifier Modules have been removed..........10 Figure 4- Removal of components is completed .............. 12 Figure 5-Connecting a test load to the power supply ............ -
Page 4: Section 1: About This Manual
EBay. Perhaps you could offset the cost of the UpdateMyDynaco kit by selling the original modules. The only part of your Stereo 120 that really needs to work is the power supply. With this kit, you’ll build good sounding, highly reliable amplifiers to replace the original amplifier modules. -
Page 5: Project Overview
Project Overview The project consists of the following steps: 1. Checking out the old Dynaco Stereo 120 power supply. 2. Removing the old amplifier modules, output capacitors, and a few associated bits, while saving some parts for re-use. 3. Assembling the updated amplifier module PC Boards. -
Page 6: Section 2: Checking The Stereo 120 Power Supply
Section 2: Checking the Stereo 120 Power Supply The only part of your old Stereo 120 that really needs to work is the power supply. In this section, we show how to check your power supply. If your amplifier modules haven’t been badly damaged, this is the simplest method of assuring your power supply is ok. -
Page 7: Section 3: Saving The Stuff That Should Be Saved
2. Plug the amplifier into the AC wall socket. 3. Standing off to one side, turn the power switch on. Observe the amp for about a minute to make sure no smoke is curling out of any of the modules. 4. -
Page 8: Removing The Right Channel Module
one wire, the LEFT power amplifier module is free to lift out as soon as you remove the two #6 screws that hold the LEFT heat sink to the chassis. Unscrew the screws, lift out the module, and cut the wire that you couldn’t reach in the previous step. Save the LEFT module and mounting hardware. -
Page 9: Figure 2-Location Diagram For Cutting Wires
Figure 2-Location diagram for cutting wires Page 9 of 32... -
Page 10: Figure 3-After The Amplifier Modules Have Been Removed
Figure 3-After the Amplifier Modules have been removed Page 10 of 32... -
Page 11: Removing C7 Right
Removing C7 RIGHT 1. Remove and save 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 12: Figure 4- Removal Of Components Is Completed
Figure 4- Removal of components is completed Page 12 of 32... -
Page 13: Section 4: Troubleshooting The Stereo 120 Power Supply
This section only applies if your power supply didn’t pass the test outlined in Section 2: Checking the Stereo 120 Power Supply. If your power supply did pass that test, move on to . This section describes how to verify proper operation of the power supply, separating power supply troubles from amplifier module troubles. -
Page 14: Just In Case - Trouble Shooting
2. Make sure that none of the other dangling wires is making contact with anything else. 3. When everyone is clear of the amplifier, plug it in, and turn it on. 4. Measure the DC voltage on the terminals of C12. 5. -
Page 15: Section 5: Building The Updated Circuit Boards
Section 5: Building the Updated Circuit Boards This section details the process of building the circuit boards. We start with an overview on this page. The specifics you need to start building begin on the next page. In general, you’ll start with the components that lay closest to the board, working your way toward the taller components. -
Page 16: Figure 7-Leads Soldered And Clipped
Figure 7-leads soldered and clipped When you’re done this section, there will only be one empty resistor slot, R16, a no-load, which will remain empty. Track your progress by placing a check-mark in the done column as you install each resistor. -
Page 17: Install The Small Capacitors And The Diodes
Install the Small Capacitors and the Diodes Now we’ll install the following small capacitors: Designation Value Marking Done? 220 pF 220 pF 47 pF Here’s what these three caps look like (not to scale): Next we install diodes D1 and D4. Be careful! Diodes have a polarity. -
Page 18: Last Capacitors And The Transistors
Last Capacitors and the Transistors Now, the medium tall polarized electrolytic capacitors: C1 and C6 are polarized. Make sure the negative sign on the capacitors faces away from the positive sign on the silk screen! Designation Value Marking Done? 47 F, 63 V 47 F, 63 V, and minus sign for polarity 47 F, 100 V 47 F, 100 V, and minus sign for polarity... -
Page 19: Solder The Lm3886 Into The Board
1. Cut a 21 1/2” length of 16 AWG solid wire from the output inductors wound around the old Dynaco output capacitors. 2. Strip back 3/8” of insulation from both ends of the wire. Be careful not to nick the conductors. -
Page 20: Figure 11-Showing Method Of Attaching Brackets To The Pcb
square in the figure should be very nearly 1” by 1”. Print this page, and set the board and brackets against the page to check the LM3886’s height above the board. 3. Match the outline of the LM3886 and the PC board to the drawing. When the match is pretty good, solder one corner pin of the LM3886. -
Page 21: Figure 12-Template For Checking Mounting Height Of Lm3886
Figure 12-Template for checking mounting height of LM3886 Carefully inspect your soldering. Make sure that all pins of the LM3886 are soldered, and that there are no solder bridges between pins. Inspect the board from both the top and the bottom! Figure 13-LM3886 installation step three, just the corner pins are soldered Page 21 of 32... -
Page 22: Final Inspection Of The Circuit Board
Figure 14-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. Looking on the component side, double check: 1. -
Page 23: Mounting The Updated Amplifier Board To The Super Heat Sink
Mounting the Updated Amplifier Board to the Super Heat Sink Figure 15-Mounting assembled PCB to super heat sink 1. In addition to the assembled circuit board with the mounting brackets in place, have the following items ready: a. The super heat sink plate b. -
Page 24: Figure 16-A Completed Amplifier Module
Figure 16-a completed amplifier module Figure 17-Showing Detail of attaching power wiring harness to C12 Figure 18-Showing the Final Wiring (shown with original, rather than super heatsinks) Page 24 of 32... -
Page 25: Section 6: Wiring In The Updated Amplifier Modules
Figure 19-Final wiring viewed from the other side of the amplifier (shown with original, rather than super heat sinks) Section 6: Wiring In the Updated Amplifier Modules This section gives the steps needed to wire the new modules into your old amplifier. Here’s the plan: 1. -
Page 26: Building And Installing The Ground Wiring Harness
bare wire on C12’s positive terminal. Keep the wires near the terminal. Solder both wires in place, and cut the extra length of bare wire extending past the terminal. Figure 17 shows a close-up of the arrangement. Figure 20-wiring harness 5. -
Page 27: Wiring The Inputs
4. Form the second of the wires along the chassis toward the place where the left channel amplifier will sit. Figure 21-Ground wiring harness Wiring the Inputs 1. The right channel twisted pair is long enough that it may be comfortably re-used. Form it down along the chassis to the place where the right channel amplifier will sit. -
Page 28: Connecting The Right Channel Amplifier Module
b. From the solder side of the board, insert the left channel white wire through the left channel INPUT eyelet and solder it on the component side. 4. Solder the black wire coming from the star ground to the remaining INGND of the left channel amplifier. -
Page 29: Making The Speaker Binding Posts User Friendly
7. Check your work. One OGND terminal will not have a wire, and the following eyelets on the PCB should each have a wire: e. VCC f. PGND g. IGND h. IGND i. INPUT j. OGND k. OUTPUT 8. Make sure that the bottom lip of the heat sink is clean, and also the place where it mounts to the chassis. -
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 there is neither smoke nor excess heating, leave the power on and move on to Test #2. -
Page 31: Figure 22-Schematic Of Amplifer Module
Figure 22-Schematic of amplifer 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...