Ramsey Electronics FM100B Instruction Manual page 42

J. POWER SUPPLY
In order to simplify operation for users around the world, the power supply
module used in the FM100B operates over a wide range of voltages.
If you already own or have built the older FM100 series you will remember that
the power supply section was quite loaded with parts. Now we provide the
whole power supply already built and ready to go. Where is the fun in that?
Well this power supply can do a lot more than our old one could. It can be run
from a variety of line voltages (85-254 VAC) so it will easily work in Europe as
well as the US without changing any jumpers! The only portion we need to
build is the 5V regulator section which is composed of three parts!
1J. Install C1, a 10 uF electrolytic capacitor. Note orientation of where the
plus symbol and the negative stripe of the capacitor are located.
2J. Install C2, the last of the 10 uF electrolytic capacitors. Orientation
again.
3J. Install VR1, the 5V voltage regulator (marked 7805). Use one of the #4-
40 1/4" screws and a lock nut to hold down the regulator flush to the board
as shown.
Take a moment to check the components you just installed (especially their
orientation). The next step is to mount the power supply to the main board
before the final wiring of the unit takes place. Please note that the switching
power supply contains high voltages! The large capacitor on the board is
charged with rectified line voltage so at any time it may have a charge of over
200V DC on it (with plenty of current capability)! Once the unit is energized,
don't go anywhere near this supply. The traces on the back of the power
supply module are also potentially lethal! Make sure any of the parts located
on the main board of the FM100B (especially under the power supply module)
are soldered close to the board. The destruction will be catastrophic should
you energize your FM100B with any of the electrolytic capacitors (C1, 51, 58,
71, or 77 in particular) or any other component touching the bottom of the
power supply module! Verify that you have a minimum of 1/8" spacing
between the bottom of the power supply module and the top any
standing components on the FM100B main board after you mount the
assembly.
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FM100B • 42
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