Download Dynalo - Detailed Construction (dgardner 5-7

DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 1 – Obtain the Dynalo parts on the Bill of Materials, including bare the printed circuit board
shown in Figure 1a. Make sure the PCB is generally free of dust and dirt. The board can be
cleaned with isopropyl alcohol or denatured alcohol if necessary. New boards that have been
stored properly require no cleaning.
Fig 1a
Step 2 – Select some 4-40 x 1/4” threaded stand-offs and some 4-40 x 3/16” machine screws.
Install the standoffs in the fours corners to make the installation of the electronic components
easier.
Fig 2a
Fig 2b
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 3 – Identify military resistor markings. The example is for the 24.9 Ω resistor used in
location R29 on the board. There are four rows of markings on this type of resistor. The last
row has the key information.
Row 1
Row 2
Row 3
Row 4
Row 1 – Manufacturer Logo - Dale
Row 2 – Date Code - 2005, week 11, J=Joint Army Navy brand
Row 3 – Type RN60 and Characteristic D=±100ppm/°C
Row 4 – Value and Tolerance - 3 significant figures, R=decimal point, F=1% tolerance.
Step 4 – Basic installation instructions for leaded resistors.
Prepare the leads of a resistor with a needle-nose plier as shown in Figure 4a. A good
construction style is have the resistance value and tolerance marking (Row 4) pointing straight
up and away from board for easy viewing and debug. It takes an extra few seconds to be nice
and neat, but it will be worth it when the board is finished.
Check the actual resistance value of the resistor with your digital multi-meter before installing it
into the board to make sure you have read the value correctly. Even the most experienced
builders can make a mistake now and then, especially late at night. It’s easier to check the value
than to de-solder a part soldered into the wrong location.
Fig 4a
Fig 4b
Slide the 24.9 Ω resistor through the holes of the R29 location as shown in Figure 4c. Flair the
leads out slightly to keep the resistor from sliding out when you flip the board over to solder it in
place as shown in Figure 4d.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Fig 4c
Fig 4d
(notice the 24R9 marking is pointing up)
Solder the resistor in place using the methods outlined in the basic solder skills section. Trim the
leads flush to the board as shown in Figure 4f and 4g.
Fig 4e
Fig 4f
(bottomside)
(bottomside)
Fig 4g
Fig 4h
(bottomside, leads trimmed flush)
(topside, resistor value clearly visible)
Step 5 – Populate Resistors that are common to all of the circuit option configurations.
Populate the following leaded resistors on the board using the method in Step 4. Proceed with
each of the resistor groups listed below, working one group at time.
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Install 16 metal film resistors with value 24.9Ω and tolerance of 1% with the marking
24R9F into reference locations R23, R24, R25, R26, R27, R28, R29, R30, R53, R54, R55,
R56, R57, R58, R59, R60.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
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Install 4 metal film resistors with value 3.32KΩ and tolerance of 1% with the marking
3321F into reference locations R18, R20, R48, R50.
Install 6 metal film resistors with value 1.00KΩ and tolerance of 1% with the marking
1001F into reference locations R7, R17, R21, R37, R47, R51.
Install 8 metal film resistors with value 4.99KΩ and tolerance of 1% with the marking
4991F into reference locations R1, R2, R8, R9, R31, R32, R38, R39. Be careful not to
accidentally use the 499Ω resistors with marking 4990F.
Install 8 metal film resistors with value 200Ω and tolerance of 1% with the marking 2000F
into reference locations R3, R4, R5, R6, R33, R34, R35, R36. Do not install any resistors
into locations R19 or R49 at this time.
Install 4 metal film resistors with value 7.5KΩ and tolerance of 1% with the marking 7501F
into reference locations R12, R13, R42, R43.
Install 4 metal film resistors with value 499Ω and tolerance of 1% with the marking 4990F
into reference locations R11, R15, R41, R45.
The board will look like this when all of the resistors listed above have been populated.
Fig 5a
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 6 – Select from several DC Offset circuit options. The Dynalo a direct coupled amplifier
circuit which means there are no series capacitors on the input circuit, nor are there any
capacitors on the amplifier output. It is desirable to reduce DC voltages offsets on the output of
the amplifier to 5mV or less when the Dynalo input is being driven by a source signal at a zero
volume level.
Option 1 – Kevin Gilmore Op-Amp Servo Option (recommended)
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Install 2 DIP-8 sockets into locations U5 and U6. Do not install the OP27 devices
into the sockets at this time.
Install 4 ceramic bypass caps with value of 0.1µF into reference locations C6, C7,
C19, C20.
Install 2 poly film caps with value of 0.33µF into reference locations C5, C18.
Install 2 metal film resistors with value 1.0MΩ and tolerance of 1% with the marking
1004F into reference locations R61, R62.
Install 2 metal film resistors with value 15.0KΩ and tolerance of 1% with the
marking 1502F into reference locations R22, R52.
Option 2 – Manual DC Offset Trim Option (alternative option)
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Do not populate any parts into locations U5, U6, C6, C7, C19, C20, C5, C18, R61,
R62, R22, R52.
Approach A – Substitute a Trim Pot for the Op-Amp Servo circuit to control the DC
Adjust node in the circuit.
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Install 2 multi-turn trim-pots with value 20K in reference locations XX. Note: It may
be helpful to preset the wiper of each potentiometer to the 10K position (center
position) before installation.
Approach B – Directly adjust the Constant Current sources with Trim Pots.
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Install the 2 metal film resistors with value 7.5KΩ and tolerance of 1% with the
marking 7501F into reference locations R12, R13, R42, R43.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 7 – Select from several Output Stage Bias control options.
Option 1 – Thermal Tracking Diode Option (recommended)
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Install the 2 metal film resistors with value 200Ω and tolerance of 1% with the marking
2000F into reference locations R19, R49.
Approach A – Solder the diodes flush to the PCB. (easier)
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Install the 4 small signal diodes of type 1N914 or 1N4148 into reference locations
D3, D4, D7, D8. Note: Install flush to the PCB.
Approach B – Thermally bond the diodes to the output transistors. (ideal)
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Wait to install the 4 small signal diodes of type 1N914 or 1N4148 into reference
locations D3, D4, D7, D8 until the output transistors are installed in a later step.
Proceed to Step 8.
Option 2 – No Thermal Compensation Option (the original Gilmore design)
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Install the 2 metal film resistors with value 511Ω and tolerance of 1% with the marking
5110F into reference locations R19, R49.
Omit the diodes and install 2 bare wire jumpers into reference locations D3, D4, D7, D8.
Note: Using pieces of trimmed off resistor lead works well for a jumper.
Step 8 – Select an appropriate Gain Setting for your application
Option 1 – Use the standard gain setting of 11. (recommended)
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Install the 2 metal film resistors with value 10.0KΩ and tolerance of 1% with the marking
1002F into reference locations R16, R16.
Install the 2 feedback compensation capacitors with value 10pF into reference locations C27,
C28.
Option 2 – Use an equation determine the gain setting. (optional)
Insert Gain Equations here.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
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Install the 2 metal film resistors with value 511Ω and tolerance of 1% with the marking
5110F into reference locations R19, R49.
Step 9 – Select Input Loading Method
Option 1 – Use a panel mount Stereo Volume Control Potentiometer (most popular)
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Select a stereo volume potentiometer with a value of 10KΩ or 20KΩ with a log
(audio) taper. Installation wiring for the potentiometer will be covered in the Casing
and Wiring section.
Do not populate any resistors into reference locations R65, R66.
Option 2 – Use a fixed resistor on the Dynalo input (required a variable output source unit)
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Install the 2 metal film resistors with value 10.0KΩ and tolerance of 1% with the
marking 1002F into reference locations R65, R66.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 10 – Review Summary of the Popular Options
Wow! Time for a beverage. For the purposes of illustration, I have selected what I believe are the
most popular options listed in Steps 6 through 9 listed above.
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Step 6 – Option 1.
Step 7 – Option 1, Approach B.
Step 8 – Option 1.
Step 9 – Option 1.
If you selected these options, the board will look something like this when Steps 6 through 9
have been completed.
Figure 10a
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 11 – Staging your transistor inventory.
One of my most influential teachers once said “Remember the 6 six P’s”. That is – “Prior
Planning Prevents Piss Poor Performance.” This is the step in process that requires you to have
some respect for planning.
Assuming you have read the Transistor Matching section and prepared (or purchased) a
sufficient inventory of gain characterized (HFE) parts with at least 12 matched pairs of 2SA1015
and 2SC1815 transistors, we can proceed.
Step 11.1 – Select the Constant Current Source transistors (2 pairs)
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Pick your two best matching pairs for reference locations (Q1 Q2) and (Q13 Q14). Ideally
you should try to get Q1 and Q2 matched within 1-2% of each other. Likewise, try to get Q13
and Q14 matched within 1-2% of each other. The pairs themselves do not need to match each
other. For example, Q1 does not need to match Q13, and Q2 does not need to match Q14.
Fig 11.1a
Fig 11.1b
Complimentary Matched Pair (left channel)
Complimentary Matched Pair (right channel)
Q1 = 2SA1015, HFE=254.5
Q2 = 2SC1815, HFE=254.3
Q13 = 2SA1015, HFE=254.3
Q14 = 2SC1815, HFE=254.3
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 11.2 – Select the Voltage Amplifier Stage transistors (2 pairs)
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Pick the next two best matching pairs for reference locations (Q3 Q4) and (Q15 Q16). Ideally
you should try to get Q3 and Q4 matched within 1-2% of each other. Likewise, try to get Q15
and Q16 matched within 1-2% of each other. Again, the pairs themselves do not need to
match each other. For example, Q3 does not need to match Q15, and Q4 does not need to
match Q16.
Fig 11.2a
Fig 11.2b
Complimentary Matched Pair (left channel)
Complimentary Matched Pair (right channel)
Q3 = 2SA1015, HFE=255.7
Q4 = 2SC1815, HFE=255.6
Q15 = 2SA1015, HFE=255.7
Q16 = 2SC1815, HFE=255.6
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 11.3 – Select the Output Stage transistors (2 sets of matched Quads)
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Precise matching the output transistor groups is a little less critical than the previous matched
pairs. Do the best you can with your remaining transistor inventory.
For the left side of the board, try to get the average HFE of (Q6, Q8, Q10, Q12) to match the
average HFE of (Q5, Q7, Q9, Q11). Try to pick the (Q6, Q8, Q10, Q12) group with HFE
values that vary no more than about 10-20%. Likewise, try to pick the (Q5, Q7, Q9, Q11)
group with HFE values that vary no more than about 10-20%.
For the right side of the board, try to get the average HFE of (Q18, Q20, Q22, Q24) to match
the average HFE of (Q17, Q19, Q21, Q23). Try to pick the (Q18, Q20, Q22, Q24) group with
HFE values that vary no more than about 10-20%. Likewise, try to pick the (Q17, Q19, Q21,
Q23) group with HFE values that vary no more than about 10-20%.
Fig 11.3a
Fig 11.3b
Complimentary Matched Quads (left channel)
Complimentary Matched Quads (right channel)
Q6 = 2SA1015, HFE= 261.5
Q8 = 2SA1015, HFE= 262.3
Q10 = 2SA1015, HFE= 262.5
Q12 = 2SA1015, HFE= 263.0
Q18 = 2SA1015, HFE= 267.9
Q20 = 2SA1015, HFE= 269.1
Q22 = 2SA1015, HFE= 269.7
Q24 = 2SA1015, HFE= 269.1
Q5 = 2SC1815, HFE= 261.7
Q7 = 2SC1815, HFE= 261.8
Q9 = 2SC1815, HFE= 263.0
Q11 = 2SC1815, HFE= 263.0
Q17 = 2SC1815, HFE= 267.9
Q19 = 2SC1815, HFE= 269.7
Q21 = 2SC1815, HFE= 269.7
Q23 = 2SC1815, HFE= 269.7
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 11.4 – Select the Input Stage Dual JFET Transistors
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The input Junction Field Effect Transistor (JFET) pair consists of a (2SK389 2SJ109) pair for
reference locations (U1 U2) on the left channel and a (2SK389 2SJ109) pair for the reference
locations (U3 U4) on the right channel.
Option 1 – Use a (2SK389 2SJ109) pair in the same Gain Class with no matching. (easier)
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Select a (2SK389 2SJ109) pair with the same gain class for use in reference locations
(U1 U2). Select a (2SK389 2SJ109) pair with the same gain class for use in reference
locations (U3 U4). Carefully cut & remove the center pin (pin 4) from the 2SK389
and 2SJ109 devices as shown in Figure 11.4a. Note that all devices in Figure 11.4a
are from gain class “BL”.
You may want the option to try a few combinations of (2SK389 2SJ109) pairs during
the Initial Setup Stage of the build process, if you have extra parts. In order to make
this process easy, I recommend that you install sockets in reference locations U1, U2,
U3, U4. A standard strip of break-away SIP socket (Fig 11.4b) or a cut piece of
ZIGZAG-20 socket (Fig 11.4c) will do the trick.
Fig 11.4a
Fig 11.4b
Fig 11.4c
Option 2 – Use a (2SK389 2SJ109) pair in the same Gain Class with Idss matching. (ideal)
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Select a (2SK389 2SJ109) pair with close match Idss parameters for use in reference
locations (U1 U2). Select a (2SK389 2SJ109) pair with the close match Idss
parameters for use in reference locations (U3 U4). Carefully cut & remove the center
pin (pin 4) from the devices 2SK389 and 2SJ109 as shown in Figure 11.4a.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 12 – Create the Thermally Bonded (Diode + Output Transistor) Sub-Assemblies
Step 13 – Install the Bipolar Transistors and JFETs according to the staging plan in Step 11 and
the visual guide shown below in Figure 13a. If you are color blind or don’t have a
color printer, you will wish to use the schematic to confirm the installation locations.
Fig 13a
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 14 – Install power supply bypass capacitors
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Install the 6 aluminum electrolytic capacitor with value 120uF and working voltage
of 35V or greater into reference locations C8, C9, C23, C24, C25, C26. The caps
are optional. They provide bulk power supply rail decoupling. Maximum part body
diameter is 12.5mm with lead spacing of 5mm.
Install the 10 poly film type capacitors with value 0.1uF and working voltage of 35V
or greater into reference locations C1, C2, C3, C12, C13, C4, C14, C15, C16, C17.
The caps are optional. They provide high frequency power supply stability.
Step 15 – Install constant current source Red LEDs
Assuming you have read the LED Matching section and prepared (or purchased) a sufficient
inventory of forward voltage characterized (VF) Red LEDs with at least 2 matched pairs, we can
proceed. VF is the voltage across the LED when it is lit up.
For my construction example, I measured about 25 Red LEDs using a 16V benchtop power
supply with a 10.0KΩ series resistor. I found a pair with a forward voltage of 1.848V. I found
another pair with a forward voltage 1.871V. Voltage in the sample set can vary by as much as
0.1 Volts. The closer the match, the lower (better) the initial DC offset voltage will be when you
start the adjustments performed in Step 17. The exact magnitude of the forward voltage is not
critical. Anything from a VF of about 1.6V to 1.9V should work.
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Install two LEDs with closely matching forward voltages in to locations D1 and D2.
Be sure to observe to correct polarity. Warning: Do not substitute LEDs with different
colors.
Install two LEDs with closely matching forward voltages in to locations D5 and D6.
Be sure to observe to correct polarity. Warning: Do not substitute LEDs with different
colors.
Step 16 – Install terminal block connectors (Hole spacing is 0.200”)
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Install a 3-position terminal block into location J5.
Install the four 2-position terminal blocks into locations J1, J2, J3, J4. As an option
you may prefer to install test loops into these locations. For illustration, I installed
test loops into locations J1 and J3. The terminal blocks make input and output
connections convenient during test and debug. Purists make wish to solder input and
output connection wires directly into the holes.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 17 – Perform Initial Power Up Tests
Congratulations! You have reached a major assembly milestone. If you selected the options
like I did in this example, your board will look something like this.
Fig. 17a
Step 17.1 – Setup your power supply.
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You will need to have a power supply with output voltages of +16V and -16V for this section
of the testing. The Dynalo Rev C board is design to run with input voltages from +15/-15V
to +16.4/-16.4V. Select a power supply with a minimum output current rating of 240mA per
rail.
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The +15V/-15V is what you get from the Elpac MW071-1950 Wall Wart.
The +16.4V/-16.4V is what you get from the tradition Dynalo Power Supply design
on http://www.Headwize.com
Make certain the power supply is operating properly at the correct output voltage and polarity
before proceeding to any hookups, to avoid damaging the board.
Step 17.2 – Power up the Board.
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DYNALO REV C – DETAILED CONTRUCTION GUIDE
Step 17.3 – Take initial DC Offset measurements.
Step 18 – Perform Initial Listening Tests
Step 19 – Install the completed Dynalo board in an enclosure
This section to be completed at a later date….
Step 20 – Listen to some Music
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