AkitikA STEREO 400 User manual

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STEREO 400/416/410
PC30 REPLACEMENT
© 2022 AkitikA, LLC
All rights reserved
Revision 1p03 – August 21, 2022

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Table of Contents
Table of Contents ................................................................................................................ 2
Table of Figures .................................................................................................................. 2
Section 1: About This Manual ............................................................................................ 3
Who Should Attempt this Project? ................................................................................. 3
Tools You’ll Need........................................................................................................... 3
Project Overview ............................................................................................................ 3
Important Safety Notes ................................................................................................... 3
About Components ......................................................................................................... 4
Recommended Solder ..................................................................................................... 4
Warranty ......................................................................................................................... 4
Section 2: Building the PC30 Board ................................................................................... 5
Resistor Installation ........................................................................................................ 6
Diode Installation ............................................................................................................ 6
Regulator Installation ...................................................................................................... 6
Capacitor Installation ...................................................................................................... 8
Removing the Old PC30 ................................................................................................. 8
Installing the new PC30 ................................................................................................ 11
Table of Figures
Figure 1-PCB for the PC30 Replacement Board ................................................................ 5
Figure 2-PC-30 connections ............................................................................................... 9
Figure 3-PC30 replacement schematic ............................................................................. 10

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Section 1: About This Manual
This manual gives the information you need to build and install a replacement PC-30 in a
Dynaco Stereo 400/410/416 Power amplifier.
Who Should Attempt this Project?
Warning: The Stereo 400/410/416 is a heavy, awkward beast to work on. It has high
voltages and large capacitors that store a lot of energy. If you’re a beginner, don’t
install this kit.
Tools You’ll Need
You’ll need the following tools:
1. flat blade screwdriver for #6 screws
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. Magnifying glass, if you’re over 42!
Project Overview
The project consists of the following steps:
1. Building the new PC30 Board.
2. Removing the original PC30 Board.
3. Installing the new PC30 Board.
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 amplifier.
 Large capacitors hold lots of energy for a long time. Before you put your hands
into the amplifier:
o Pull the AC plug!
o Wait 1 full minute for the capacitors to discharge!
 Remove jewelry, rings, and watches 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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About Components
We reserve the right to make design and/or component changes at any time without prior
notification.
Recommended Solder
The kit must be assembled with 63/37 (tin/lead) Rosin Core solder1. The recommended
diameter is 0.031 inches. Kester p/n 24-6337-8800 solder is a very good choice.
Warranty
With the exception of fuses, Akitika will replace for free any component of a correctly
assembled PC-30 replacement that fails within one year of the date of purchase when it
has been used in home stereo applications. It is the responsibility of the kit builder to
install the replacement part(s). This warranty applies to the original purchaser only. It
does not apply to units that have been physically or electrically abused, modified without
prior factory authorization, or assembled with other than 63/37 Rosin Core solder.
Akitika LLC’s liability shall in no event exceed the cost paid to Akitika LLC for the kit.
1 https://en.wikibooks.org/wiki/Practical_Electronics/Soldering has entries for both 60/40 and 63/37 solder
blends. This reference calls out a preference for 63/37 because it is a eutectic solder, which it says is less
prone to cold solder joints.

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Section 2: Building the PC30 Board
This section details the process of building the PC30 board. Warm up your soldering iron
and clean the tip. The soldering your about to do will be much easier if your iron is tuned
up and ready.
Find the PCB as shown in Figure 1.
Figure 1-PCB for the PC30 Replacement Board
We’ll start with the components that sit closest to the PCB, the resistors. Then we’ll
move on to the diodes. Finally, we’ll install the IC’s and capacitors.

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Resistor Installation
These resistors are all ¼ Watt, 1%, metal film resistors. Install these resistors into the
silk-screen side of the PCB, flush with the PCB. A 1 Watt power resistor will be installed
in a later section of this manual.
Lead spacing is 0.5”
Desig
Value
Color Code
Done

R1
24
3
Red,
Yellow, Orange, Black, Brown
R2
12
1
Brown, Red, Brown, Black, Brown
R3
2260
Red, Red, Blue, Brown, Brown
R4
1130
Brown, Brown, Orange, Brown, Brown
R5
4020
Yellow, Black, Red, Brown, Brown
R6
4020
Yellow, Black, Red, Brown, Brown
Diode Installation
The diodes are rated at 1 Amp and 400 Volts. Diodes are polarized, so you must align the
white stripe on the diode with white stripe on the silk screen. Insert the diode into the silk
screen side of the board and solder them on the solder side. The diodes are installed flush
to the PCB. Note that LED’s will be installed later.
Lead Spacing 0.4”
Desig
Type
Marking
Done

D1
1N4004
4004
D2
1N4004
4004
D3
1N4004
4004
D4
1N4004
4004
D5
1N4004
4004
D6
1N4004
4004
D7
1N4004
4004
D8
1N4004
4004
Power Resistor Installation
Install R318, a 3.3 Ohm 1 Watt resistor.
LED Installation
Install LED1 and LED2. Unlike resistors, LEDs are polarized. There is only one right
way to install them. You can identify the positive and negative side of an LED as
follows:
1. Given uncut leads, the longer of the two leads is the ANODE (positive) lead.
2. Looking down onto the body, you’ll see a round outline with a flat on one side.
That flat is closest to the CATHODE (negative) lead.

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Figure 2-The Cathode or negative lead of an LED is nearest the flat side of the package
Note that the LED1 and LED2 silk-screens have a + sign making the ANODE or positive
side of the LED.
Figure 3-Locating LED Cathode and Anode on the PCB
Regulator Installation
Now you’ll install IC1 and IC2, the Positive and Negative regulators, along with their
heatsinks. You’ll use 4-40x5/16” Philips head screws, 4-40 keps nuts, and thermal
compound.
Desig
Value
Done

IC1
LM317 adjustable positive regulator
IC2
LM337 adjustable negative regulator
Refer to the cover illustration for assembly details. Double check that the regulator type
matches the silk screen location. Spread a thin film of thermal compound on the back of
each regulator before installing it onto the heatsink and screwing the assembly down to
the board.

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Capacitor Installation
With the exception of C3, all of the capacitors installed here are polarized. Make sure to
align the non-negative side of the capacitor with the plus sign.
Desig
Value
Done

C1
2200 uF, 25 Volts
C2
2200 uF, 25 Volts
C3
10 nF, 250V (non
-
polar)
C4
47 µF, 35 Volts
C5
47 µF, 35
Volts
Removing the Old PC30
Label the following wires prior to removing the old PC30. You may find that
dismounting the old PC30 from its mounting brackets may make this easier. Remove and
reserve the hardware. It will be reused to install the new PC30.
PC30
Eyelet
Description Notes about connections on
the PC30
1 To positive 75V fuse common (fuse block
terminals 3 and 4)
Terminals 1 and 2 are
connected
2
To positive diode bridge output, terminal 3
3
+13V output, to PC29 eyelet 18
4 To negative 75V fuse common(fuse block
terminals 7 and 8)
Terminals 4 and 5 are
connected
5
To negative diode bridge output, terminal 1
6
Chassis ground lug near C2
7
-
13V output, to PC29 eyelet 12
8
-
13
No connection
14
First blue wire from
power transformer
Terminals 14 and 15 are
connected
15
No connection
16
Blue/Yellow wire from power transformer
Terminals 16, 17, and 18 are
connected
17
Ground connection for PC29 eyelet 15.
18
No connection
19 Second blue wire connection from power
transformer
Terminals 19 and 20 are
connected
20 Common Terminal of Dynaguard Lamps DL and
DR
Figure 4-PC-30 connections may be useful to you as you disconnect the wires from the
old PC-30 and reconnect wires to the new PC-30.

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Figure 4-PC-30 connections

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Figure 5-PC30 replacement schematic

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Installing the new PC30
Mount the PC30 to the bracket using the original hardware that you had previously set
aside. Solder the labeled wires into the new numbered eyelets in the new PC30.