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Designation Type
Description
Done? (
)
Q2
2N3904, TO-92
60 V NPN bipolar transistor
Q3
2N3904, TO-92
60 V NPN bipolar transistor
Q4
2N3904, TO-92
60 V NPN bipolar transistor
Q6
2N5401, TO-92
150 V PNP bipolar transistor
Q7
2N5401, TO-92
150 V PNP bipolar transistor
Don’t use too much solder on the transistor leads. This is one place where the spacing
is close enough that extra solder might cause short circuit between two leads on a
given transistor. Note that Q4’s collector and base are connected by the circuit board.
Install the Big Capacitors
Install C6 and C7.
C6 and C7 are polarized. Be careful to get the polarity correct. Double check their
polarity before you solder them in place. They have large terminals, so it will take a
fair amount of heat and solder.
Designation Type
Description
Done? (
)
C6
10,000 µF/80V
Electrolytic capacitor
C7
2200 µF/160V
Electrolytic capacitor
Caution: C6 and C7 are not identical! Be sure to put each in its correct place!
Final Inspection of the Circuit Board
After you’ve taken a break, look over your completed circuit board one more time.
Looking on the component side, double check:
1.
polarity (banded end) of diodes matching the banded end on the silk screen.
2.
polarity of C1, C2, C6, C7 and C7 (minus sign away from the indicated plus sign
on the silk screen).
If you get one of these polarities wrong, there is a good chance that the power supply
won’t work, or there will be damage when you power it up.
Look at the solder side of the board. Make sure that:
1.
All component leads are soldered (it’s easy to forget one or two, and that will
cause either unreliable operation, or no operation at all!)
2.
There are no solder bridges between pads which should be isolated. Solder
bridges may stop the power supply from working correctly.
Power Supply Final Assembly
In this section, you’ll install Q5 while you mount the power supply circuit board on its
heatsink. Some kits have a silver colored finned heatsink. Other kits have a black-
anodized heat sink. In either case, the power supply heatsink is about 5 3/8” wide. The kit
has one other silver colored double wide heatsink that that will be used for both amplifier
modules
2
.
2
Some kits may have instead been supplied with two separate black 4” wide heatsinks, one for each
amplifier module.
