13
improve heat transfer. The time to do this depends on the heat of your iron, and the size of the
tip. Once you see the solder flow across the tab, keep the heat on the work for at least ten seconds
longer. Larger tips will heat the work faster and produce better results. Maintain constant and
firm pressure on the part with tweezers as you do this, and when you remove the iron, keep the
pressure on until you are sure the solder has solidified. This pressure, plus the solder flowing
under sustained heat, ensures that your iron heats the tab, the tab heats the pad, and the pad
accepts solder. If the pad does not heat up sufficiently
, it won’t accept solder.
When the work
cools, make sure the chip is bonded to the big pad by pulling up on it. Under magnification, inspect
the smaller pins to make sure they are all soldered and there are
n’t
gobs of solder bridging the
pins. Then, install the remaining PSU parts. Install two wire jumpers as shown. Trimmed rectifier
diode (ex: 1N4001) leads are a good choice for these jumpers, due to their increased thickness.
Figure 3 - Jumpers on PSU Board
PSU
Resistors
Inductors
240r
2 100uh
2
2k4
2
27k
2 Active Components
580-SPM15-150-Q12P-C
2
Trimmers
LM2991
1
500r
2 TL1963A
1
Capacitors (ceramic/film)
Locking Headers
4n7
4 .156 x 2
1
220n
2 .156 x 5
1
Capacitors (electrolytic)
10u
2
47u
3