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Summary of Contents for AkitikA GT100
- Page 1 GT100 TWO CHANNEL AUDIO POWER AMPLIFIER ASSEMBLY MANUAL © 2012 AkitikA, LLC All rights reserved Revision 1p30 June 24, 2012 Page 1 of 44...
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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 ......................4 Important Safety Notes ....................5 About Components ......................5 Section 2: Building the Power Supply PCB ............... -
Page 3: Table Of Figures
Install the Top ......................36 Section 5: Testing It Out ....................36 Section 6: Specifications and Schematics................. 36 Appendix 1 - Resistor Color Code................41 Appendix 2 - Preparing a Shielded Cable End ............. 42 Table of Figures Figure 1-Installing resistors ....................6 Figure 2-Form the cathodes of D4-D7 as shown (banded end denotes cathode) .... -
Page 4: Section 1: About This Manual
Figure 39-Shield wired end prep completed ..............44 Section 1: About This Manual This manual gives the information you need to build Akitika LLC’s GT100 Stereo Power Amplifier. Who Should Attempt this Project? You can build this kit if you can: 1. -
Page 5: Important Safety Notes
Important Safety Notes By purchasing, using, or assembling 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: Building The Power Supply Pcb
Section 2: Building the Power Supply PCB This section details the process of building the circuit board. 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 towards the taller components. - Page 7 We recommend the following procedure: 1. Insert all the resistors of the same value, e.g. R2, R3 and R4. 2. Bend the leads as described above. 3. Solder the leads on the back of the board. 4. Clip the leads. Track your progress by placing a check-mark in the done column as you install each resistor.
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Page 8: Install The Diodes
Install the Diodes Now install the diodes. Be careful to observe the polarity markings on the diodes. You’ll notice that one end of the diodes has a band. Match the banded end of the diode with the banded end of the silk screen. Warning: Don’t cut the leads of D4-D7 until after the leads have been formed and the diodes have been soldered into the PCB. -
Page 9: Identifying The Glass Body Diodes
Identifying the glass body diodes The glass body diodes have the following identifying marks. If your vision is like mine, you may need good light and a magnifying glass. • 1N4148, D8-D11, has the number 48 visible • BZX55B33B, D1 and D14, has the number 33 visible •... -
Page 10: Install The Small Capacitors
Install the Small Capacitors Now install the capacitors: Designation Value Description Done? ( ) 10 F 100V electrolytic (polarized), cylindrical shape 10 F 100V electrolytic (polarized), cylindrical shape 10 F 100V electrolytic (polarized), cylindrical shape 100 nF 50V, Z5U, +/- 20%, marked 104 10 nF 400V, film, 20%, box shaped Notes:... -
Page 11: Install The Transistors
Install the Transistors You may have to spread the outside leads a bit to make it easier to insert them into the board. Do not install Q5 now. It will be installed later. Orient the transistor so its body shape matches the silk-screen outline. Leave the top of the transistor about ½”... -
Page 12: Install The Big Capacitors
Install the Big Capacitors Install C6 and C7. C6 and C7 are polarized. Be careful to get the polarity correct. Double check their polarity before you solder them in place. They have large terminals, so it will take a fair amount of heat and solder. -
Page 13: Figure 6-Note The Rounded Brackets Used For The Power Supply Heatsink And Pcb
Figure 6-Note the rounded brackets used for the power supply heatsink and PCB (XXX needs new picture) 1. Use two 6-32x3/8” screws to fasten a pair of mounting brackets to the heat sink, placing the screw through the 9/64” clearance hole in the bracket. Note that one hole in the mounting bracket is a 9/64”... -
Page 14: Attach The Power Supply Ground Wire
Figure 8-Installing Q5 on the heatsink and to the PCB Figure 9-Remember to solder Q5's leads 5. Solder the three leads of Q5 on the component side of the board, and clip the leads. Inspect your work from both the top and the bottom of the board to make sure there are no solder bridges between the leads. -
Page 15: Section 3: Assembling The Amplifier Circuit Boards
Section 3: Assembling the Amplifier 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 12-Leads Soldered And Clipped
Figure 12-leads soldered and clipped When you have completed this section, there will only be one empty resistor slot, R16, a no-load, which will remain empty. Keep track of your progress by placing a check-mark in the done column as every resistor is installed. -
Page 17: Install The Small Capacitors And The Diodes
Designation Value Color Code Done? Brown, Black, Black, Gold, Brown Brown, Black, Black, Gold, Brown Brown, Black, Black, Gold, Brown Brown, Black, Black, Gold, Brown Brown, Black, Black, Black, Brown 51K1 Green, Brown, Brown, Red, Brown 51K1 Green, Brown, Brown, Red, Brown 100K Brown, Black, Black, Orange, Brown 100K... -
Page 18: Last Capacitors And The Transistors
Here’s what the diodes look like (not to scale): Next we install LEDs D2 and D3 (Light Emitting Diodes – note that in normal operation, these diodes will be dark. However, in a fully darkened room, you’ll see a dull green glow from the powered LEDs.) 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... -
Page 19: Winding The Output Inductor
And the non-polarized capacitors: Designation Value Marking Done? 1 F, 63 V or 1 uF, 63 V or 100V (box shaped mylar 100V capacitor) 0.1 F, 100V 0.1 F, 100V 0.1 F, 100V Install the transistors. Spread the outside leads a bit to make it easier to insert them into the board. -
Page 20: Final Inspection Of The Circuit Board
4. Wind 5 turns of wire, closely spaced, so it looks like Figure 15. When you get to the end of the coil, fold the end across the existing turns, toward the L1B hole. 5. Pull the end of the wire through the L1B hole, and solder it on the back of the board. -
Page 21: Installing The Lm3866 And Mounting The Amplifier Board To The Heat Sink
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. Look at the solder side of the board. Make sure that: 3. All component leads are soldered (it’s easy to forget one or two, and that will cause either unreliable operation, or no operation at all!) 4. -
Page 22: Figure 17-Mounting The Pcb To The Heat Sink
Figure 17-mounting the PCB to the heat sink 6. Place a dab of thermal compound on the back of the LM3886 and spread it into a thin film, being careful to keep the leads clean. 7. Fasten the LM3886 to the heatsink using a 6-32x3/8” screw. Tighten all the mounting screws as you make sure that the LM3886 is parallel to the plane of the board. -
Page 23: Attach The Amplifier Module Wires
Figure 19-a completed amplifier module 10. Repeat the process to build the amplifier module for the second channel. Attach the Amplifier Module Wires Designate one of the completed amplifier modules as LEFT, and the other as RIGHT. To prevent errors, it may help to make and apply LEFT and RIGHT masking tape lapels to the amplifier modules. -
Page 24: Attaching Right Module Power Wires
Figure 20-shielded cable for left channel 9. Working with one end of the shielded cable, insert the red wire into the IN eyelet, inserting it from the solder side, and soldering it on the component side. 10. Working from that same end, insert the drain wire into the INGND eyelet closest to the IN eyelet. -
Page 25: Section 4: Wiring It All Together
11. Cut a 8” length of 18 AWG stranded white wire. Remove 3/8” of insulation from both ends. 12. Insert the first end of the white wire into the OUT eyelet of the PCB, inserting it from the solder side, and soldering it on the component side. 13. -
Page 26: Speaker Binding Posts
Figure 22-positioning the RCA input jacks and ground lug Speaker Binding Posts The two speaker output connectors are heavy duty 5-way binding posts. Install them into the chassis according to the following diagram. Make sure that the Red binding post is on the top, and that the black binding post is on the bottom. -
Page 27: Figure 23-Wiring Iec Power Connector
i. Black wire to L (line) terminal. ii. White wire to N (neutral) terminal. Figure 23-Wiring IEC power connector 4. Slide the ½” pieces of black heat shrink tubing up and over the terminals and shrink them in place using the tip of your solder iron, passed quickly and lightly over the heat shrink tubing. -
Page 28: Transformer Installation
10. Starting with the switch outside the chassis, push the FASTONs on the bottom switch terminals as indicated in Figure 25. Figure 25-Installing power wires on the switch 11. Make sure that the | is at the top of the opening before you insert the rocker switch into the chassis. -
Page 29: Figure 26-Joining The Secondaries
Figure 26-joining the secondaries 6. Mount the toroidal transformer to the chassis using the hardware shown in Figure 27. Rotate the toroid so that the primary wires (with the FAST-ON connectors) will comfortably reach the switch and the secondary wires comfortably reach the power supply board PCB. -
Page 30: Testing The Power Supply
7. Slide the FASTON connectors from the toroidal power transformer on the indicated terminals of the switch. Either wire can go to either terminal. It may help to keep a hand in front of the switch as you push the FAST-ONs in place. Figure 28-connecting up the power transformer 8. -
Page 31: Final Amplifier Wiring
1. Open the fuse drawer in the IEC power connector and install the main fuse and the spare fuse. Close the fuse drawer. 2. Make sure that the power switch is in the off position (the bottom part of the rocker switch, labeled with a 0, is flush with the front panel). -
Page 32: Figure 30-Spread Thermal Compound On The 3/8" Wide Ridge
Figure 30-spread thermal compound on the 3/8" wide ridge 3. Place the amplifier module into the chassis and secure it in place using two black 6/32-1/2” flat-head screws inserted from the bottom of the chassis. Hint: The easiest way to do this is to hang the side of the amp over the edge of the work table (the mass of the power transformer should keep the amp on the table, but be careful, please). -
Page 33: Wiring Amplifier Power
Wiring Amplifier Power 1. Identify the red/black zip cord that connects to the left amplifier module VCC and PGND pins. Route them along the chassis floor and toward the VCC and PGND pins of the power supply. a. Insert the red wire into the VCC pin closest to the large capacitor, C6, from the component side of the PCB and solder it on the solder side. -
Page 34: Wiring Input Connections
Wiring Input Connections 1. Left Module: Identify the shielded cable on the left module that connects to the IN and INGND eyelets of the PCB. Route it through the air to the left channel RCA input jack. a. Solder the red wire to the center terminal of the jack. b. -
Page 35: Visual Inspection
2. Right Module: Prepare a 2.5” length of 18 AWG black stranded wire, stripping 3/8” of insulation from both ends. a. Solder a #6 lug to one end of the black wire. b. Locate another #10 lug. Solder the following three wires to it: i. -
Page 36: Install The Top
Install the Top Slide the top in place. Install the 15 #2x1/4” black Phillips head screws that keep the top in place. Section 5: Testing It Out Once the visual inspection looks ok and any shortcomings have been corrected, you can apply power to the amplifier and check for the lack of smoke. - Page 37 Separation: Input Impedance: 51 K Ohms Sensitivity: 1 Volt RMS input produces 20.59 Volts RMS output Weight: 15.5 lbs Page 37 of 44...
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Page 38: Figure 34-Power Supply Schematic
Figure 34-Power Supply Schematic Page 38 of 44... -
Page 39: Figure 35-Amplifier Module Schematic
Figure 35-Amplifier Module Schematic Page 39 of 44... -
Page 40: Figure 36-Overall Wiring
Figure 36-Overall Wiring Page 40 of 44... -
Page 41: Appendix 1 - Resistor Color Code
Appendix 1 - Resistor Color Code Figure 37-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... -
Page 42: Appendix 2 - Preparing A Shielded Cable End
Appendix 2 - Preparing a Shielded Cable End For the ultimate control of noise on the input wiring, we have supplied shielded cable. This section tells how to prepare the ends of the shielded cable. This process will be repeated four times, at both ends of both input cables (although the cables will have different overall lengths). - Page 43 Separate and twist the drain wire. Peel back and remove the foil. Remove the plastic wrap from the red and black wires. Drain, Red, and black wires are exposed now that gray insulating jacket, foil shield, and plastic over-wrap have been removed. Page 43 of 44...
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Page 44: Figure 38-Shielded Cable End, As Of Step 4
1. Remove ½” of insulation from the black wire and save the ½” piece of insulation. 2. Cut Red wire so that 1” protrudes beyond the shielded cable’s gray jacket. 3. Cut the drain wire so that 1” protrudes beyond the shielded cable’s gray jacket. 4.
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