DYNACO PAT-4 User manual

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PAT-4 PHONO UPGRADE
ASSEMBLY MANUAL
© 2016 AkitikA, LLC
All rights reserved
Revision 2p13 January 15, 2015

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Table of Contents
Table of Contents ................................................................................................................ 2
Table of Figures .................................................................................................................. 2
Section 1: About This Manual ............................................................................................ 3
Who Should Attempt these Projects? ............................................................................. 3
Tools and Supplies You’ll Need ..................................................................................... 4
Recommended Solder ..................................................................................................... 4
Project Overview ............................................................................................................ 4
Important Safety Notes ................................................................................................... 4
Section 2: About the Phono Preamp Upgrade .................................................................... 5
Effects of the Modification ......................................................................................... 5
Before you Begin ........................................................................................................ 5
Prerequisites ................................................................................................................ 5
Preparing to Remove the Circuit Boards .................................................................... 6
PC Board Modifications ............................................................................................. 7
Adding R30 if your PCB doesn’t have a place for it .................................................... 11
Installing the DRD4 Kit ................................................................................................ 11
PAT-4 PWR Modifications (Optional) ..................................................................... 11
Inspection and Preliminary Reassembly ................................................................... 12
Final Wiring and Reassembly ................................................................................... 13
If you want 5 high level inputs and 1 phono input ................................................... 13
Final Sanity Checks .................................................................................................. 17
Prepare to Reconnect your PAT-4 to your Music System ........................................ 17
Appendix 1: The Toothpick Trick ................................................................................ 17
Appendix 2: First Class De-soldering ........................................................................... 18
Schematics .................................................................................................................... 19
Record Playing Reminders ........................................................................................... 21
Appendix 3 - Preparing a Shielded Cable End ............................................................. 22
Table of Figures
Figure 1-Stock PCB (before upgrade) ................................................................................ 8
Figure 2-Stock PCB (after upgrade) ................................................................................... 8
Figure 3-Detail of R2-C3-white-wire connection ............................................................... 9
Figure 4-Preparing C4 for installation .............................................................................. 10
Figure 5-Insert R30 in from the back of the board ........................................................... 11
Figure 6-Final step of R30 installation in those cases where holes don’t already exist on
the PCB ............................................................................................................................. 11
Figure 7-Both PCBs reassembled onto U brackets, ready for installation (DRD4 kit
installed also) .................................................................................................................... 12
Figure 8-Changes to grounds for 5 high level input version of PAT-4 ............................ 14
Figure 9-Adding shielded cable as part of the 5 high level input modification ................ 16
Figure 10-Schematic shows phono preamp with modifications (3 High level and 3 phono
level inputs) ....................................................................................................................... 19
Figure 11-Schematic when modified for 1 phono and 5 high level inputs ....................... 20

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Section 1: About This Manual
This manual gives the information you need to install the phono upgrade to the Dynaco
PAT-4 Preamp. Manuals starting from Rev 2p13 cover the Rev B version of the kit,
which substitutes a 1K resistor for the original 4K7 R1, instead of a jumper. 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)
The blue light kit changes the light in the power switch from original orange to beautiful
blue.
The Line Amp Distortion Reducer drops the distortion of the Line Amp by a factor of
ten. The Line Amp is the stage that includes the volume and tone controls. All sound
from the preamp passes through the Line Amp. This upgrade makes everything played
through the PAT-4 sound better.
The Tone Control Switch replaces the existing Hi Filter switch with a two position rotary
switch. In the OFF position, the tone controls are disabled. In the 15 position, tone
controls maintain their normal function. After this modification, the other two positions
of the HI FILTER switch (10 and 7) are not available. You can install optional resistors
(not provided) that drop the Line Amp gain when the tone controls are off. This drops the
gain of the Line Amp, increasing Signal to Noise Ratio.
The regulated power supply kit replaces the original diodes, 3-section cap, and resistors
with an electronically regulated power supply. When you install the PAT4PWR supply,
you dramatically reduce the hum in the PAT-4. It mounts conveniently in existing holes
in the PAT-4.
These upgrades can be installed in any combination, but 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)

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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. needle nose pliers (helpful, but not strictly necessary)
3. pencil type soldering iron of 25 to 50 Watts (no huge honking soldering guns or
blowtorches)
4. wire cutters and strippers
5. de-soldering tools (see the Appendix 1 and Appendix 2)
6. Magnifying glass, if you’re over 42!
7. 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. Labeling, then de-soldering all the wires from each circuit board.
2. Replacing a number of components from the phono section of the preamp with
the supplied components.
3. Adding a few wires to the circuit boards.
4. Re-attaching the wires to the circuit boards (with a few modifications).
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 4 to 8 dB quieter than the stock preamp.
 Phono High and Phono Cer inputs will no longer be active.
 You’ll have two more phono inputs because:
o The special input will be equalized for phono.
o The Tape Head input will be equalized for phono.
 Alternatively, you can change the wiring to provide 5 high level inputs and 1
phono input:
o The phono input will be active
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 phono positions.
 Your cartridge will actually 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. The upgrade modifies
the topology such that the input impedance looks very close to 47K across the
whole audio band.
Before you Begin
This modification gives you a wonderful opportunity to tweak the gain of your phono
preamp. That lets you trade off sensitivity with phono preamp overload. There is no one
right answer. The best answer depends upon your equipment. Here’s the procedure:
Listen to a record with your preamp, cartridge, and turntable in its stock form. Note the
“clock position” of the volume control when you’re listening about as loud as you’d
every reasonably expect to.
 Write down the clock position of the loudest sane setting here____________.
 If the volume “clock position” (for any input) is never above 12 O’clock, then you
might want to drop the gain of the phono preamp by 6 dB. You’ll do that by
installing R2 equal to 243 Ohms. That makes the preamp more resistant to
overload, and will make it cleaner on the most highly modulated records.
 If you often run your preamp with the volume clock position higher than 12
o’clock, then you should maintain the stock gain, and you’ll install R2 equal to
121 Ohms (very near the original stock value of 120 Ohms).
Think about how you’d like to proceed, and circle your preference here:
 Drop gain by 6 dB to increase overload margin, R2=243 Ohms
 Keep gain at stock level. R2=121 Ohms.
Prerequisites
The PAT4PWR supply must be installed in order to install 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 upgraded design.

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Preparing to Remove the Circuit Boards
1. Disconnect the PAT-4 from your music system.
2. Unplug the power cord and allow the preamp to sit for one minute before moving
on.
Caution: Be sure that the preamp power is unplugged! 120 VAC can be lethal! 240 VAC
can be lethal!
3. Remove the 4 screws that hold the cover in place, 2 on the left side and 2 on the
right side.
4. Lift the cover straight up and set it aside in a safe place.
5. The kit is supplied with two sets of number labels, one for the right channel, and
one for the left channel.
6. Mark all the wires that connect to the left channel (it’s the one closer to the back
of the chassis) PCB using the supplied labels. These labels have an eyelet number,
and the letter B, for back. Make sure that the label numbers match the eyelet
numbers etched in the copper traces on the solder side of the PCB. This will help
you get the preamp back together after the modifications.
7. Desolder all the wires from the left channel PCB after they are labeled. Be careful
not to put too much stress on the selector switch.
8. Mark all the wires that connect to the right channel (it’s the one closer to the front
of the chassis) PCB using the supplied labels. These labels have an eyelet number,
and the letter F, for Front. Make sure that the label numbers match the eyelet
numbers etched in the copper traces on the solder side of the PCB. This will help
you get the preamp back together after the modifications.
9. De-solder all the wires from the right channel PCB after they are labeled. Don’t
put too much stress on the selector switch as you remove these wires.
10. The wires that used to go to eyelets 6, 7, and 8 will not be reconnected to the
PCB. Carefully identify just these three wires, clip them near where they meet the
selector switch, and discard these three wires. In subsequent assembly, eyelets 6
and 7 will remain open, and eyelet 8 will get a wire from the -17.5 Volt power
supply.
11. Repeat the process for wires 6, 7, and 8 of the right channel PC board, the one
closer to the front of the preamp.
12. Prepare to remove the two PCB’s and the bracket that holds them in place by
carefully dressing the wires out of the way,
13. Remove the two 6-32 nuts, lock washers, and screws that hold the U-shaped
brackets that retain the circuit boards to the bottom of the chassis.
14. Remove the assembly of the brackets and the two PCB’s from the chassis.
15. Remove the 4-40 hardware that holds the PCB’s to the U-shaped bracket. Keep
track of the lock washers, and remove them so they don’t float around inside the
preamp or on the PC board.
16. Once both boards are removed, clear the solder from the numbered eyelet holes. If
you have official de-soldering equipment, use it. If you don’t, you may want to
use the Toothpick Trick (see Appendix 1 and 2) to clear the solder from these
eyelets. Doing so will make reassembly much easier. Check for daylight visible
through all the holes, and/or that they will pass a piece of bare hook-up wire.

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PC Board Modifications
The listed procedure will be repeated for both left and right channel PC boards. In
general, you will:
 Remove the indicated component
 Clear the solder from the associated PCB mounting holes
 Install the new component, carefully following the directions, as you’ll mount
some of the new components in unconventional ways to generate the upgraded
topology of the phono preamp.
 Make a check-mark the left or the right channel board as you complete the step.
Remove this Install this Done

Done

Remove R1 Replace R1 by a 1K resistor (brown, black,
black, brown, brown)1
 
Remove R3 Replace with 33K2 resistor (orange, orange, red,
red, brown)
 
Remove R4 Replace R4 by a jumper made from the supplied
22 AWG black solid wire
 
Remove R5 Replace R5 with a 48K7 Ohm resistor (yellow,
gray, violet, red, brown).
 
Remove R6

Replace with 3K32 resistor (orange,
orange, red, brown, brown) supplied, or
 Alternatively, you can replace R6 with
the supplied 1650 Ohm resistor (brown,
blue, green, brown, brown), but that
requires you to modify your Update-
mydynaco PAT4PWR.
 
Remove R7 Replace with 56K2 resistor (green, blue, red,
red, brown)
 
Remove R8 Replace with 4k75 resistor (yellow, violet,
green, brown, brown)
 
Remove R9 Replace R9 with a 25K5 Ohm resistor (red,
green, green, red, brown).
 
Remove R30, if
your board has it. If
it’s present, it will
be parallel to C4,
between C4 and the
eyelet edge of the
board.
If your board has a place for R30 then
replace R30 with the enclosed 48K7
resistor (yellow, gray, violet, red,
brown).
If your board doesn’t have a place for R30
then you’ll wait to the end of this section
to add R30 to the board.
 
1 In Rev A of the kit, R1 was replaced by a jumper. Using a 1K resistor provides slightly higher white noise
levels but typically less hum.

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Figure 1-Stock PCB (before upgrade)
Figure 2-Stock PCB (after upgrade)

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Remove C1 Replace C1 with a 0.33 µF film capacitor
(carries the number 334 on the body).
 
Remove C3. Replace C3 with a 1000 µF electrolytic
capacitor. Slide a ½” piece of insulation stripped
from the supplied black 22 AWG wire over the
negative lead of C3. Stretch the negative lead
out as shown in Figure 3, leaving it full length
Install the positive lead of the new cap into the
hole formerly occupied by the negative lead of
the old C3.
 
Remove R2 Replace R2 by either a
1. 121 Ohm resistor, stock value, (brown,
red, brown, black, brown), or a
2. 243 Ohm resistor, gain lowering value,
(red, yellow, orange, black, brown),
depending upon how you answered the volume
control question at the beginning of the manual.
Connect only the lead that goes to Q1’s emitter,
leaving the other lead unconnected for now. See
Figure 3.
 
Cut a 2” long piece of white stranded 22 AWG
wire. Strip ¼” of insulation from each end.
 
Twist together the free ends of C3 and R2 with
one end of the white wire from the previous
step. Solder the connection.
 
Connect the free end of the white wire to the
component hole on the PCB. See Figure 3.
 
Figure 3-Detail of R2-C3-white-wire connection

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Remove C7 Nothing goes in its place 

Remove the jumper
directly below C7
Nothing goes in its place. 

Remove Q1 Replace Q1 by the MPSA18. Match the
orientation of the flat to Figure 2.
 
Remove Q2 Replace Q2 with an MPSW45A. The flat side
faces the near edge of the board, see Figure 2.
 
Remove C16
2
Replace C16 with the supplied 47 µF 50 Volt
capacitor. Make sure to get the polarity correct.
 
Figure 4-Preparing C4 for installation
Cut a 2” white wire (22 AWG stranded) and
strip ¼” of insulation from both ends. Twist the
white wire around one lead of the new C4, a 3.3
µF 63 Volt film cap and solder it. See Figure 4.
 
Remove the old C4,
a 50 µF 25 Volt
capacitor.
Place the new C4 assembly into the board as
shown in Figure 2 and Figure 7. For now, solder
C4’s right hand lead on the back of the board,
but not the left-hand lead.
 
Solder the free end of the white wire from C4
into eyelet 6.
 
If your PCB has a location for R30, then solder
the unsoldered (left-hand) wire of C4 on the
back of the board, and you’ve completed the
PCB Modifications.
 
If your PCB doesn’t have a location for R30,
then see the next section for directions on
installing R30 on the back of the board.
 
2 C16 isn’t part of the phono preamp. It’s part of the high level stage. However, we’ll replace it because it
often goes bad due to its proximity to the heat generated by R20.

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Adding R30 if your PCB doesn’t have a place for it
Only perform the operations in this section if your PAT-4 is one of the early production
models that did not have a place on the PCB for R30.
Insert a 48K7 Ohm resistor into the back of the board as shown in Figure 5. Note that two
leads fit in the one hole that connects to eyelet 5: C4’s still unsoldered lead, and R30.
Figure 5-Insert R30 in from the back of the board
Solder both sides of R30. On the Eyelet 5 side, you’ll solder C4 and R30 leads
simultaneously. Clip the extra lead length on both sides of the board.
Figure 6-Final step of R30 installation in those cases where holes don’t already exist on the PCB
Installing the DRD4 Kit
If you purchased a DRD4 Kit, this is the perfect time to install it. See the DRD4 manual
for details. The special DRD4 transistor and heat sink replaces the stock transistor Q4 and
its star-shaped heat sink.
PAT-4 PWR Modifications (Optional)
The modification in this section must be performed only if you chose to install the 1650
Ohm resistor for R6. That change doubles the output current available from the phono

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preamp. Using R6=1650 Ohms can be beneficial in some cases, but is not necessary. It’s
most likely to matter if you have a high output cartridge playing highly modulated
records with lots of high frequency content.
Making this modification nearly doubles the current drawn by the phono preamp, so
you’ll also need to make a modification to the PAT4PWR power supply.
PAT4PWR Power Supply Modification
Remove R15 Replace with 2K resistor (red, black, black, brown, brown)
Remove R19 Replace with 2K resistor (red, black, black, brown, brown)
Inspection and Preliminary Reassembly
Inspect your work for good solder joints and freedom from solder bridges. Touch up any
questionable connections now. It will be painful to have to disassemble things to repair
something later. Verify that the eyelets along the tops of the boards are free of solder and
are ready to accept the labeled wires.
Attach the PC boards to the U-shaped bracket. Use the original 4-40 screws and the new
4-40 keps nuts. They have captive lock washers that simplify reassembly. Screw the
assembly of PC-boards and U-shaped bracket back into the PAT-4 chassis. Use the
original 6-32 screws and the new 6-32 keps nuts (also with captive lock washers).
Figure 7-Both PCBs reassembled onto U brackets, ready for installation (DRD4 kit installed also)

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Final Wiring and Reassembly
These Steps Are Important! Done

Done

You’ll see that the PEC 555005 attaches to a number of pins around the
phono inputs. Cut lead 3 of PEC 555005 near where it attaches to the
center conductor of the RCA jack labeled “Phono Low”, leaving the
lead as long as possible. Bend the lead out of the way, and tape it if
necessary to keep it from shorting anything. Repeat this for both the left
and right channel PEC’s. Don’t cut the wire that goes to the selector
switch! It must remain in place.
 
Using the wire labels to guide you, reconnect the rest of the wires to the
front preamp PCB, with the exception of eyelets 6, 7 and 8.
 
Run a wire from eyelet 8 of the left-channel board to one of the
negative 17.5 volt outputs (N17P5) of the PAT4PWR board.

Using the wire labels to guide you, reconnect the rest of the wires to the
back preamp PCB, with the exception of eyelets 6, 7 and 8.
 
Run a wire from eyelet 8 of the right-channel board to the other of the
negative 17.5 volt outputs (N17P5) of the PAT4PWR board.

If you want 5 high level inputs and 1 phono input
Perform the modifications in this section ONLY if you want 5 high level inputs and 1
phono input. After performing these modifications, TAPE HEAD and SPECIAL will
both accept normal high level inputs.
If you want to have the capability for three phono inputs (using the phono, tape head, and
special inputs), then skip this section.
Ground Changes Done

Desolder the ground wire from FRONT PC-16, eyelet 2. Cover the bare
portion with electrical tape, but leave it connected to the switch.

Desolder the ground wire from REAR PC-16, eyelet 2. Cover the bare
portion with electrical tape but leave it connected to the switch.

Remove the following ground wires at the rear panel:
a. Short Lug 2-3 to Short Lug 4-5
b. Short Lug 13-14 to Short Lug 15-16
Add the following ground wires at the rear panel:
a. Short Lug 4-5 to Short Lug 6-7
b. Short Lug 15-16 to Short Lug 17-18

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Figure 8-Changes to grounds for 5 high level input version of PAT-4

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Disconnect the following wires from the PC-16’s by de-soldering them. Done

Front PC-16, Eyelet 1 
Front PC-16, Eyelet 5 
Twist the above two wires together, solder, and tape the connection. 
Rear PC-16, Eyelet 1 
Rear PC-16, Eyelet 5 
Twist the above two wires together, solder, and tape the connection. 
Refer to Figure 8 as you perform these steps: Done

Desolder (or clip) the wire that connects to back-panel terminal 1 (this
is the left channel phono input jack). Untwist this wire from the others,
and route it and connect it to eyelet 5 of the REAR PC-16. (On some
PAT-4’s, it may be so short that you’ll have to replace this wire with a
longer wire.)

Desolder (or clip) the wire that connects to back-panel terminal 12 (this
is the right channel phono input jack). Untwist this wire from the
others, and route it and connect it to eyelet 5 of the FRONT PC-16.

Reconnect the phono jacks with Shielded Cable Directly to the PC-16’s Done

Prepare an 11” long piece of shielded cable. See Appendix 3. Connect
one end to the RIGHT channel PHONO LO input jack as follows:
a. Ground wire to ground terminal of phono low connector
b. Center conductor to signal terminal of phono low
connector

Connect the other end of that piece of shielded cable:
c. Ground wire to eyelet 2 of the FRONT PC-16
d. Center conductor to eyelet 1 of the FRONT PC-16

Prepare a 5” long piece of shielded cable. Connect one end to the LEFT
channel PHONO LO input jack as follows:
e. Ground wire to ground terminal of phono low connector
f. Center conductor to signal terminal of phono low
connector

Connect the other end of that piece of shielded cable:
g. Ground wire to eyelet 2 of the REAR PC-16
h. Center conductor to eyelet 1 of the REAR PC-16


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Figure 9-Adding shielded cable as part of the 5 high level input modification

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Final Sanity Checks
Here are a few last tests before you reconnect your PAT-4 to your music system. With
the top still off, plug in the AC mains. Turn on the power switch. Set your meter to DC
volts. Connect one lead of the meter to ground.
Be careful! These steps are performed with the power connected and
turned on!
Done

Done

The voltage on eyelet 8 of both preamp PCB’s should measure between
-17 and -18 Volts DC (with respect to ground).
 
The voltage on eyelet 4 of both preamp PCB’s should measure between
17 and 18 volts DC (with respect to ground).
 
The voltage on eyelet 12 of both preamp PCB’s should measure
between 36 and 40 volts DC (with respect to ground).
 
Prepare to Reconnect your PAT-4 to your Music System
 Turn off the power.
 Remove the AC plug from the wall socket.
 Replace the cover.
 Reinstall the four screws that hold the cover in place.
 Reinstall the PAT-4 to your music system.
 Notes:
o Use the PHONO LOW input for your turntable. The other two PHONO
inputs, PHONO HIGH and PHONO CER are disconnected.
o If you chose the three phono wiring, then:
 The TAPE HEAD input will also be equalized for a turntable, so it
could be used as an input for a second turntable
 The SPECIAL input will also be equalized for a turntable, so it
could be used as an input for a third turntable
o If you chose the 5 high level and one phono wiring, then:
 The TAPE HEAD input is a high level input
 The SPECIAL input is a high level input
Appendix 1: 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.
All you’ll need is a soldering iron and some toothpicks with sharp points. The diameter of
the pointed part of the toothpick must be smaller than the diameter of the hole that you’re
trying to clear.
Heat the solder land on the component side of the board until the solder flows. Insert the
toothpick from the component side of the board while pushing and twisting the toothpick.
If the solder has melted, the toothpick should push through the board, displacing the

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solder. Remove the soldering iron, but let the toothpick remain in the hole until the solder
has solidified. Now remove the toothpick. There should be a hole through the solder
sufficiently large to allow you to insert the component lead or wire.
Sometimes, a bit of the toothpick will break off in the hole. If this happens, use a stiff
piece of wire to push the toothpick fragment out of the hole.
Appendix 2: First Class De-soldering
De-soldering can be easy if you have the right tools. Through the years, I’ve used a
number of “make-do” methods:
 The toothpick trick – not bad for clearing a hole if the diameter is big enough.
 Sold-a-pult- these spring loaded, one shot solder vacuums are a step in the right
direction, but can’t supply both heat and vacuum action simultaneously. Some
people cut a v-shaped hole in the tip to poke the soldering iron through, but it’s
still a bit hit or miss, and frustrating.
 Solder wick- this is copper braid that you heat up in connection with the joint. The
idea is that the solder wicks into the copper braid, away from the joint. It’s still
slow and frustrating, and takes so much heat that you worry about the board.
At some point, you’ll decide that you deserve a better way to desolder, and you’ll buy a
heat source with a built in continuous vacuum pump. Big industrial units can cost many
hundreds of dollars. Here’s the best value I’ve found so far, the Hakko 808. I bought
mine for about $180, and it’s worth every penny. Often when I de-solder components, the
action is so clean that they just fall out of the board.
Once you’ve treated yourself to a real de-soldering tool like the Hakko 808, you’ll
wonder why you waited so long.

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Schematics
Figure 10-Schematic shows phono preamp with modifications (3 High level and 3 phono level inputs)

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Figure 11-Schematic when modified for 1 phono and 5 high level inputs