Related Manuals for AkitikA PAT-4
Summary of Contents for AkitikA PAT-4
- Page 1 PAT-4 UPGRADES ASSEMBLY MANUAL Line amp distortion reducer Tone control switch © 2013-2022 AkitikA, LLC All rights reserved Revision 2p02 August 24, 2022 Page 1 of 24...
-
Page 2: Table Of Contents
C16 Leakage and Replacement – PAT4RENEW boards ..........13 Pre-wiring the Tone Control Switch ................13 Optional Gain Reducing Resistors ................15 Disassembling the PAT-4 Preamp ................16 Removing the HI FILTER switch................16 Mounting the tone control switch ................17 Wiring in the tone control switch................ - Page 3 Figure 6-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 ....15 Figure 7-Installing the treble no-click resistors on eyelets 16, 17, and 18 .......
-
Page 4: Section 1: About This Manual
Section 1: About This Manual This manual gives the information you need to build and install the various upgrades to the Dynaco PAT-4 Preamp. As of this writing, the following PAT-4 upgrades are available from Updatemydynaco, a division of Akitika LLC: ... -
Page 5: Project Overview
Use the appropriate section for the job at hand. 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: ... -
Page 6: Section 2: Line Amp Distortion Reducer
Section 2: Line Amp Distortion Reducer Line Amp Characteristics The line amp in a properly working PAT-4 has about 0.02% distortion when driving a 100K Ohm load at 1 Volt RMS. Typical units measure about -74 dB for the second harmonic of a 1 kHz test signal, and perhaps -90 dB for the third harmonic. -
Page 7: Modifying The Left Channel Circuit Board
c. Eyelet 4 d. Eyelet 5 e. Eyelet 6 f. Eyelet 7 7. Repeat the process for the right channel PC board, the one closer to the front of the preamp. As you remove each wire, place a clearly marked masking tape label on the wire with the number of the eyelet from which the wire was removed. -
Page 8: Figure 1-Applying Thermal Compound And Installing The Heat Sink On The Mpsw45
indicated places. Note that the emitter of the transistor goes toward the bottom of the PCB (away from the eyelets, see Figure 5). d. Solder the three leads of the new transistor in place. Figure 1-applying thermal compound and installing the heat sink on the MPSW45 Page 8 of 24... -
Page 9: Figure 2-Similar Series Of Heat Sink Installation Pictures For Ztx614
Figure 2-Similar series of heat sink installation pictures for ZTX614 Page 9 of 24... -
Page 10: Figure 3-New Transistor With Heatsink Installed On Pcb
Figure 3-New transistor with heatsink installed on PCB Figure 4-MPSW45A and ZTX614 Pinout Page 10 of 24... -
Page 11: Modifying The Right Channel Circuit Board
Figure 5-circuit board as seen from solder side. The modification replaces Q4 Modifying the Right Channel Circuit board Now it’s time for a second judgment call. You probably have enough access to the right channel PCB that you can remove Q4, the metal transistor with the clip-on heat-sink, with no further disassembly. - Page 12 3. Re-fasten the u-shaped brackets to the bottom of the chassis. 4. Reinstall the cover using the 4 screws (2 on each side) that hold it in place. 5. You’re ready to listen to music with lower distortion. Page 12 of 24...
-
Page 13: Section 3: Tone Control Switch
It’s important to check C16 for leakage. The quickest and easiest way to do so is to rotate the bass control while the PAT-4 is connected to your power amp and speakers. Listen carefully for a scratching sound as you rotate the Bass pot. - Page 14 4. Dress the wires from steps 1-3 off to the right, keeping them together. A piece of masking tape around the wires may be helpful. 5. Bend a hook in the ¼” uninsulated portion of a green wire, insert it through the lower BASS 1 hole, and crimp it in place.
-
Page 15: Optional Gain Reducing Resistors
Figure 6-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 Check Your Work Review your work against Figure 6. -
Page 16: Disassembling The Pat-4 Preamp
1 minute before starting this section. Here are the steps to disassemble the PAT-4 preamp to the extent you’ll need to in order to gain access to remove the Filter switch and replace it with the Tone Control Switch. -
Page 17: Mounting The Tone Control Switch
To remove the HI FILTER switch: 1. Cut the 6 wires near where they enter the HI FILTER switch. 2. Coil the two black wires, leaving them out of the way; near, but not making electrical contact to, the bottom of the chassis. 3. -
Page 18: If You Are Installing Tone Control Switch With Original Dynaco Circuit Boards
b. Route the red wire of the pair to the open center terminal of the portion of the treble pot closest to the front panel. Remove ¼” of insulation, and solder the wire to the middle terminal of the pot. 6. -
Page 19: Installing The Treble No-Click Resistors
If you have PAT4RENEW Circuit boards, this function is already built-in. There is no need to perform this step if you have installed the PAT4RENEW circuit boards. Skip ahead to “Reassemble the PAT-4”. If you have original PAT4 circuit boards, then you will add the resistors as shown in this section. -
Page 20: Reassemble The Pat-4
Connect the negative lead of the meter to ground. 4. Remaining clear of the exposed 120 Volts, plug the PAT-4 in and power it up. 5. Observe the DC micro-ammeter. As the capacitor charges at first, there will be significant charging current. -
Page 21: Gain Trim Resistors
C16 is originally 50 µF, but 47 µF is an equally fine replacement. It should have a working voltage rating of greater than or equal to 25 Volts. Why does C16 become leaky? It sits right above R20, a 620 Ohm, 1 Watt resistor that dissipates about 640 mW. - Page 22 Gain Trim Resistor Value Gain Reduction Open circuit 0 dB (e.g. no effect) 1.53 dB 3.02 dB 6800 4.08 dB 3300 6.7 dB 2200 8.46 dB 1210 or 1200 Ohms 11.23 dB The unmodified high level stage has about 21 dB of gain when driving a high impedance load and the volume control is turned fully clockwise.
-
Page 23: Schematic
Schematic Figure 9 shows how the tone control switch fits into the high level amplifier stage. Figure 9-Schematic of the preamp high level stage showing the addition of the tone control switch Page 23 of 24... -
Page 24: Appendix: The Toothpick Trick
Appendix: The Toothpick Trick This appendix describes an easy way to clear the solder from a hole in the PCB. It can also be used to clear the solder from terminals on pots or jacks. Doing so makes it easier to install a new component, or reinstall wires that were temporarily removed to allow access to some other component.
Need help?
Do you have a question about the PAT-4 and is the answer not in the manual?
Questions and answers