Related Manuals for DYNACO STEREO 120
Summary of Contents for DYNACO STEREO 120
- Page 1 UPDATING THE DYNACO STEREO 120 SOLID STATE POWER AMPLIFIER © 2011, Daniel M. Joffe All rights reserved Revision 10.0 Page 1 of 32...
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Page 2: Table Of Contents
Removing the Output Zobel Networks ..............11 Salvaging the Heat Sinks from the Amplifier Modules ..........13 Section 3: Checking the Stereo 120 Power Supply ............13 Prepare and Connect the Test Load ................13 Test the Power Supply ....................14 Just In Case –... - Page 3 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- Separating heat sinks and circuit boards ............13 Figure 6-Connecting a test load to the power supply ............14 Figure 7-The first four resistors are installed with leads bent on the back side, but not yet soldered.
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Page 4: Section 1: About This Manual
Stereo 120 Power Amplifier up to date using UpdateMyDynaco replacement 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: Important Safety Notes
Important Safety Notes By purchasing this kit, you have agreed to hold UpdateMyDynaco 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. Always unplug the power before working on the amplifier. ... -
Page 6: Section 2: Saving The Stuff That Should Be Saved
Section 2: Saving the Stuff that Should Be Saved Opening Up the Amplifier 1. Make sure the amplifier is unplugged! 2. Remove the four screws along the outside edge of the bottom that hold the cover in place (see Figure 1). Figure 1-Location of the four screws that hold the cover to the base 3. -
Page 7: Removing The Right Channel Module
The wire from C7 LEFT - terminal to Close to LEFT PC-14 LEFT PC-14 eyelet 11. eyelet 11 The wire from the LEFT input socket to Close to LEFT PC-14 LEFT PC-14 pin 12 (typically a green eyelet 12 wire). The wire from the LEFT input socket Close to LEFT PC-14 ground to LEFT PC-14 pin 13 (this is... - Page 8 Similar to before, you may not be able to reach your cutters to RIGHT Q6 E terminal. Don’t worry. We’ll make it easier now, while we check your work to this point. With the exception of this one wire, the RIGHT power amplifier module is free to lift out as soon as you remove the two #6 screws that hold the RIGHT heat sink to the chassis.
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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 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: Salvaging The Heat Sinks From The Amplifier Modules
3. Try not to get too much on your skin! Section 3: Checking the Stereo 120 Power Supply The only part of your old Stereo 120 that really needs to work is the power supply. After you’ve completed the previous section, only the power supply remains in the chassis. -
Page 14: 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 15: There's No Voltage At All
There’s No Voltage at All Check: 1. Is the AC socket powered? 2. Is the amp plugged in? 3. Is the power turned on? Remove the power, check and replace the fuse with a properly rated fuse. Sometimes, fuses just get tired. Sometimes they blow to prevent a disaster. At this point, we’re not sure what the case is here. -
Page 16: Section 4: Building The Updated Circuit Boards
Section 4: Building the Updated Circuit Boards The next few pages detail the process of building the circuit boards. The general strategy starts with the components that lay closest to the board, working your way toward the taller components. In general, we will: 1. -
Page 17: Figure 8-Leads Soldered And Clipped
Figure 8-leads soldered and clipped When you’re done this section, there will only be two empty slots for resistors: 1. R16, a no-load, which will remain empty. 2. R15, a power resistor, which we will load later. Keep track of your progress by placing a check-mark in the done column as every resistor is installed. -
Page 18: 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: Next we install diodes D1 and D4. Be careful! Diodes have a polarity. Make sure the band on the diode aligns with the banded end of the silk screen! Designation Value... -
Page 19: Last Capacitors And The Transistors
Figure 9-showing LED cathode orientation 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... -
Page 20: Winding The Output Inductor
1. Cut a 21” length of solid wire. A great place to get it is from the output inductors wound around the old Dynaco output capacitors (see Figure 10). 2. Strip back 0.5” of insulation from one end of the wire. -
Page 21: Figure 10-Starting To Wind The Output Inductor
Figure 10-Starting to wind the output inductor Figure 11-finishing step for the output inductor Page 21 of 32... -
Page 22: Solder The Lm3886 Into The Board
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. 1. -
Page 23: Final Inspection Of The Circuit Board
If you miss a right angle by a little, don’t worry. Since you’ve only soldered two pins down, it’s easy enough to reheat those two pins, and move the LM3886 up and down a bit until it sits properly. Once the LM3886 mounting looks good, solder the rest of the pins. -
Page 24: Mounting The Updated Amplifier Board To The Heat Sink
Mounting the Updated Amplifier Board to the Heat Sink 1. Use a #8 by ½” Phillips-head screw, a nut, and lock-washer to secure the mounting brackets to the PC board. Use the round hole in the bracket, not the elongated hole. Figure 14-attaching first bracket to the board 2. -
Page 25: Figure 16-Circuit Board Mounted To Heat Sink
the loose fibers before you use them. This keeps the cotton from interfering with a good thermal connection. 6. Assemble the LM3886 and circuit board to the heat-sink plate as shown in the Figure below, using the 4-40 hardware, finger-tight, but not snug. 7. -
Page 26: Section 5: Wiring In The Updated Amplifier Modules
Section 5: Wiring In the Updated Amplifier Modules This section gives the steps needed to wire the new modules into your old amplifier. You will build two wiring harnesses, a power wiring harness, and a ground wiring harness. Once they are completed, you will bolt them to the existing star ground connection. -
Page 27: Building And Installing The Ground Wiring Harness
8. Insert the left channel black wire through the left channel PGND eyelet and solder 9. Insert the right channel red wire through the left channel VCC eyelet and solder it. 10. Insert the right channel black wire through the left channel PGND eyelet and solder it. -
Page 28: Wiring The Outputs
1. Solder the left channel black wire (ground) into the remaining INGND eyelet of the left channel PCB. 2. Solder the left channel green (signal) wire into the IN eyelet of the left channel PCB. 3. Solder the right channel black wire (ground) into the INGND eyelet of the right channel PCB. -
Page 29: Section 6: Testing The Completed Amplifier
wires. If your binding posts are already correctly oriented, skip this step. If not, here’s the procedure that should be applied to whichever of the 4 binding posts don’t have the correct orientation: 1. Loosen the binding post (red or black plastic part) until you can see the hole in the mounting stud. - Page 30 a. Left channel red to black binding post should show a DC voltage of less than 100 mV if the amp has been on for about 1 minute . The longer the amp is on, the lower the DC output voltage will be. b.
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Page 31: Figure 21-Schematic Of Amplifer Module
Figure 21-Schematic of amplifer module Page 31 of 32... -
Page 32: Resistor Color Code
Resistor Color Code Figure 22-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...