AkitikA PAT-4 Manuel utilisateur
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PAT-4 PHONO PREAMP
REPLACEMENT (PAT4PPR)
ASSEMBLY MANUAL
© 2017 AkitikA, LLC
All rights reserved
Revision 1p08 January 25, 2017
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Table of Contents
Table of Contents ................................................................................................................ 2
Table of Figures .................................................................................................................. 2
Section 1: About This Manual ............................................................................................ 4
Who Should Attempt these Projects? ............................................................................. 4
Tools and Supplies You’ll Need ..................................................................................... 4
Recommended Solder ..................................................................................................... 5
Project Overview ............................................................................................................ 5
Important Safety Notes ................................................................................................... 5
Section 2: About the Phono Preamp Upgrade .................................................................... 6
Effects of the Modification ......................................................................................... 6
Prerequisites ................................................................................................................ 6
Building the PAT4PPR Circuit Boards....................................................................... 6
Component Order............................................................................................................ 7
Install the Resistors ......................................................................................................... 7
Prepare and Add Shielded Cables to the Inputs ........................................................ 10
Install the Mounting Brackets ................................................................................... 10
Preparing to Install the Assembled PAT4PPR Circuit Board ................................... 11
Drilling Mounting Holes in the PAT-4 Chassis ........................................................ 11
Connect the RCA Jacks ............................................................................................ 11
Move Power Wires ................................................................................................... 12
Move Selector Switch Wires .................................................................................... 13
Converting to Accept 5 high level inputs and 1 phono input ................................... 14
Inspection and Preliminary Reassembly ................................................................... 16
Final Sanity Checks .................................................................................................. 16
Prepare to Reconnect your PAT-4 to your Music System ........................................ 16
Record Playing Reminders ........................................................................................... 16
Gain Tweaks ................................................................................................................. 17
More Tweaks ................................................................................................................ 17
Schematics .................................................................................................................... 18
Specifications ................................................................................................................ 20
Appendix 1: The Toothpick Trick ................................................................................ 21
Appendix 2 - Preparing a Shielded Cable End ............................................................. 22
Appendix 3 - Resistor Color Code ................................................................................ 24
Table of Figures
Figure 1-Component side of the phono preamp PCB before loading ................................. 6
Figure 2-Installing resistors ................................................................................................ 7
Figure 3-Shielded cable installation (right channel shown here)...................................... 10
Figure 4-Use 6-32x1/4" screws to attach mounting brackets ........................................... 10
Figure 5-Locating the mounting holes .............................................................................. 11
Figure 6-locating the two added 9/64" mounting holes .................................................... 11
Figure 7-Connecting Left Channel input jack and 0.01 µF capacitor .............................. 12
Figure 8-Selector Switch wire identification .................................................................... 13
Figure 9-Back Panel Re-wiring ........................................................................................ 15
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Figure 10-Phono Preamp Schematic Page 1 ..................................................................... 18
Figure 11-Phono Preamp Schematic Page 2 ..................................................................... 19
Figure 12- Shield wire end prep completed (right channel) ............................................. 23
Figure 13-demonstrating the resistor color code .............................................................. 24
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Section 1: About This Manual
This manual gives the information you need to build and install the PAT-4 Phono Preamp
Replacement (and Upgrade), part number PAT4PPR, into your Dynaco PAT-4 Preamp.
As of this writing, the following other PAT-4 upgrades are available from
Updatemydynaco, a division of Akitika LLC:
Blue Light Kit (BLUE)
Line Amp Distortion Reducer (DRD4)
Tone Control Switch (TCS)
Electronically Regulated Power Supply (PAT4PWR)
Line Stage Replacement Components (P4LSRC)
Phono section upgrade (PAT4LP)
In my opinion, this kit, the PAT4PPR is preferable to the PAT4LP, even though the
PAT4PPR costs more. Why?
The PAT4PPR kit is easier to build and install than the PAT4LP kit.
The PAT4PPR kit has a tight layout with ground-planes and bypass capacitors
that give it great high-frequency stability and noise rejection.
The PAT4PPR kit has a built-in second order high-pass filter that minimizes the
woofer wobble caused by record warp.
The PAT4PPR kit has a built-in second-order lowpass filter that makes it much
less likely to pick up external signals like switching transients and radio stations.
The PAT4PPR is installed much farther from the power supply, so picks up much
less of the stray hum fields inside the PAT-4. This makes it very quiet and free of
hum. The only hum you will pick up comes from the phono cables outside of the
PAT-4.
Note: the phono upgrade kit requires the PAT4PWR supply to be installed.
Who Should Attempt these Projects?
You can build this kit 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, and
3. Read and follow directions.
It helps if you:
1. know a bit about electronics, or
2. have a friend who knows a bit about electronics
3. can get to YouTube to watch a few helpful videos about the assembly process (not
available as of this version of the manual)
Tools and Supplies You’ll Need
You’ll need the following tools:
1. flat blade screwdrivers for #4 and #6 screws, #2 Philips head screwdriver
2. a power drill with a 9/64” drill bit. A center punch is also helpful, as you will be
drilling two holes into the bottom of the PAT-4 Chassis.
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3. needle nose pliers (helpful, but not strictly necessary)
4. pencil type soldering iron of 25 to 50 Watts (no huge honking soldering guns or
blowtorches)
5. wire cutters and strippers
6. de-soldering tools (see the Appendix 1 and Appendix 2)
7. Magnifying glass, if you’re over 42!
8. A multi-meter for measuring Ohms and DC volts is handy, but not strictly
necessary
Recommended Solder
The kit must be assembled with 60/40 Rosin Core solder. The recommended diameter is
0.032 inches. Among many such sources of solder, I have used Radio Shack part number
64-009. It contains 8 oz. of solder, which is much more than you’ll need to assemble this
kit.
Project Overview
Broadly, the project consists of the following steps:
1. Building the PAT4PPR circuit board.
2. Adding two screw holes to the bottom of the chassis.
3. Transferring a few wires from the phono preamp section of the original preamp
circuit boards to the new phono preamp.
4. Fastening the new phono preamp in place and performing a few sanity checks.
5. Reassembling the preamp.
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.
Always unplug the power before working on the equipment.
Large capacitors hold lots of energy for a long time. Before you put your hands
into the equipment:
o Pull the AC plug!
o Wait 1 full minute for the capacitors to discharge!
Remove jewelry and rings from your hands and wrists, or anything that might
dangle into the amplifier.
If working in the amplifier, keep one hand in your pocket, especially if you’re
near the power supply or power supply wires. This can prevent serious shocks.
Build with a buddy nearby. If you’ve ignored all the previous advice, they can
dial 911 or get you to the hospital.
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Section 2: About the Phono Preamp Upgrade
Effects of the Modification
The phono preamp will be at least 4 dB quieter than the stock preamp. Internally
generated hum will be reduced by much more than that.
The phono equalization will be much more accurate, providing truer sound.
You will change the wiring to provide 5 high level inputs and 1 phono input:
o The PHONO LOW input will be active, accepting a moving magnet
cartridge.
o Tape Head and Special inputs will be converted to accept high level inputs
The preamp won’t clunk when you switch it in and out of the phono position.
Your cartridge will see the correct loading impedance. The original PAT-4 design
used a form of feedback biasing that made its input impedance look inductive,
falling to 10K ohms or less at low frequencies. This kit presents an input
impedance that looks very much like 47 K Ohms in parallel with 220 pF across
the whole audio band.
Prerequisites
The PAT4PWR supply must be installed along with the phono preamp upgrade. The
reason is that the PAT4PWR supply generates a -17.5 Volt supply that is used to bias the
phono preamp in the PAT4PPR.
Building the PAT4PPR Circuit Boards
This section details the process of building the phono preamp circuit board. We start with
an overview on this page. The specifics you need to start building begin on the next page.
The bare PCB is shown in Figure 1.
Figure 1-Component side of the phono preamp PCB before loading
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Begin by carefully emptying the contents of the parts envelope into a broad soup bowl, as
shown below. In general, you’ll start with the components that lay closest to the board,
working your way towards the taller components. You will:
1. Install the resistors
2. Install the capacitors
3. Install the transistors
Component Order
You’ll notice that the component designations in the directions don’t go exactly in order.
We have grouped them so that all components with the same value appear together. This
makes assembly easier. You’ll find in the parts kit that similar parts, e.g. 3 1K resistors,
are typically (though not always) taped together.
Install the Resistors
In general, you install the resistors by placing the body on 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 you solder them in place. Try to bend the leads in
a direction that won’t lead to solder bridges between traces that should remain
disconnected.
Figure 2-Installing resistors
We recommend the following procedure:
1. Insert all the resistors of the same value, e.g. R4 and R7.
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. Check resistor values with a meter, or by reading the color code1. Orient the
1 See “Appendix 3 - Resistor Color Code” on page 24 to see how to read resistor color codes.
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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.
Here are two assembly hints:
1. Finding the components: The PC Board has two essentially identical layouts, one
for each channel:
a. Left channel along the top half of the PCB.
b. Right channel along the bottom half of the PCB
c. You’ll often find that pairs of identical resistor values are separated by 13.
For example:
i. R4 and R17, separated by 13, are both 158 Ohms.
ii. R4 and R17 are in essentially the same left to right position on the
PCB, with R4 in the left channel, and R17 in the right channel.
2. The resistor leads are spaced at 0.4”. If you have a lead bender, this will speed up
and neaten your assembly. A lead bender is not required.
Desig Value Marking Done☑
R4 158 Brown, green, white, black, brown □
R17 158 Brown, green, white, black, brown □
R2 1k Brown, black, black, brown, brown □
R3 1k Brown, black, black, brown, brown □
R10 1k Brown, black, black, brown, brown □
R14 1k Brown, black, black, brown, brown □
R16 1k Brown, black, black, brown, brown □
R23 1k Brown, black, black, brown, brown □
R1 22k Red, red, black, red, brown □
R15 22k Red, red, black, red, brown □
R13 27K Red, violet, black, red, brown □
R26 27K Red, violet, black, red, brown □
R5 30K1 Orange, black, brown, red, brown □
R18 30K1 Orange, black, brown, red, brown □
R6 3320 Orange, orange, red, brown, brown □
R7 3320 Orange, orange, red, brown, brown □
R19 3320 Orange, orange, red, brown, brown □
R20 3320 Orange, orange, red, brown, brown □
R11 47k5 Yellow, violet, green, red, brown □
R12 47k5 Yellow, violet, green, red, brown □
R24 47k5 Yellow, violet, green, red, brown □
R25 47k5 Yellow, violet, green, red, brown □
R8 5900 Green, white, black, brown, brown □
R21 5900 Green, white, black, brown, brown □
R9 75K0 Violet, green, black, red, brown □
R22 75K0 Violet, green, black, red, brown □
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Now you’ll install the non-polarized capacitors. We start with the smallest capacitors, and
work toward the larger capacitor values. These capacitors are not orientation sensitive.
Desig Value Marking Done☑
C12 100 pF 101, axial □
C25 100 pF 101, axial □
C5 220 pF 221, axial □
C18 220 pF 221, axial □
C6 680 pF 681, axial □
C19 680 pF 681, axial □
C13 2.7 nF 272, blue ceramic radial cap □
C26 2.7 nF 272, blue ceramic radial cap □
C2 10 nF 10nF1K0 □
C15 10 nF 10nF1K0 □
C1 47 nF 47n F 630 □
C14 47 nF 47n F 630 □
C10 0.1 µF µ1J100 □
C11 0.1 µF µ1J100 □
C23 0.1 µF µ1J100 □
C24 0.1 µF µ1J100 □
C3 0.33 µF 0.33J63 □
C4 0.33 µF 0.33J63 □
C16 0.33 µF 0.33J63 □
C17 0.33 µF 0.33J63 □
C9 3.3 µF 3.3k63 □
C22 3.3 µF 3.3k63 □
The following capacitors are electrolytic capacitors. The polarity is important. Be sure to
look at the polarity as marked on the silk screen, and make it agree with the capacitor
markings. Note that the 47 µF capacitor foot print doesn’t quite match the PCB, but it
installs reasonably well.
Desig Value Marking Done☑
C7 47 µF, 25V See the value column □
C20 47 µF, 25V See the value column □
C27 47 µF, 25V See the value column □
C8 1000 µF, 10V See the value column □
C21 1000 µF, 10 V See the value column □
Match the shape of the transistor body to the shape of the silk-screen. Leave about 3/8” of
space between the bottom of the transistor package and the PCB. Don’t get too much heat
onto the transistors.
Desig Value Marking Done☑
Q1 MPSA18, high gain NPN MPSA18 □
Q3 MPSA18, high gain NPN MPSA18 □
Q2 MPSA45, Darlington MPSA45 □
Q4 MPSA45, Darlington MPSA45 □
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Prepare and Add Shielded Cables to the Inputs
For lowest hum, you must use shielded cable between the PHONO LOW RCA Jacks and
the inputs on the PCB. Prepare two 4” lengths of shielded cable:
1. One for the right channel, using the red conductor and the drain wire.
2. One for the left channel, using the black conductor and the drain wire.
Details on the preparation of the shielded cables can be found in Appendix 2 - Preparing
a Shielded Cable End. Prepare both ends of both pieces of shielded cable now, as it will
make it much easier to later complete installation of the input wiring.
Figure 3-Shielded cable installation (right channel shown here)
Connect the wires as follows:
1. Right channel signal wire (red) to the eyelet labeled INRIGHT
2. Right channel drain wire (bare wire covered with added gray outer jacket) to the
eyelet labeled GNDRIGHT.
3. Left channel signal wire (black) to the eyelet labeled INLEFT
4. Left channel drain wire (bare wire covered with added gray outer jacket) to the
eyelet labeled GNDLEFT.
Double check that you have not reversed the ground and signal wires.
Install the Mounting Brackets
Use 6-32x1/4” sems screws to install mounting brackets as shown in Figure 4. Make sure
the brackets are straight before you tighten them.
Figure 4-Use 6-32x1/4" screws to attach mounting brackets
Ce manuel convient aux modèles suivants
1
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