Install The To-92 Package Integrated Circuits; Install The To-220 Power Transistors; Figure 2-Front And Back Views Of Q6 Mounted On Heat Sink - DYNACO PAT-4 Assembly Manual

Designation Type
Q1 2N5551, TO-92
Q4 2N5551, TO-92
Q2 2N5401, TO-92
Q5 2N5401, TO-92
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 TO-92 Package Integrated Circuits

Although the package looks the same as the transistors, the three integrated circuits
installed in this step are actually voltage regulators. You may have to spread the outside
leads a bit to make it easier to insert them into the board.
Orient the regulator so its body shape matches the silk-screen outline. Leave the top of
the regulator about ½" off the board! The lead length prevents stress on the body and
keeps the regulator safe from too much heat during the soldering operation.
Designation Type
U1 TL431
U2 TL431
U3 TL431
Don't use too much solder on the regulator integrated circuit leads. This is one place
where the spacing is close enough that extra solder might cause short circuit between two
leads on the device.

Install the TO-220 Power Transistors

The TO-220 package looks like this (there may be some variation in the plastic molding):
Install a heat sink on Q6, the TIP32C PNP power transistor before you solder it into the
board. Use a 6-32.x1/4" sem-screw (has a built-in lock-washer) and a 6-32 keps nut (also
has a built in lock washer). No thermal compound is needed.

Figure 2-Front and Back views of Q6 mounted on heat sink

Description
150 V NPN bipolar transistor
150 V NPN bipolar transistor
150 V PNP bipolar transistor
150 V PNP bipolar transistor
Description
2.5 V adjustable shunt regulator
2.5 V adjustable shunt regulator
2.5 V adjustable shunt regulator
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