
Mounting the Pots, LEDs and Switches
If you are using the recommended Alpha pots, then they can support the PCB with specially
manufactured pot brackets. You will not normally need any further support for the board.
When constructing the board, fit the pot brackets to the pots by the nuts and washers supplied
with the pots. Now fit them into the appropriate holes in the PCB. But only solder the three,
or six, pins that connect to the pot.
Do not
solder the pot bracket at this stage. When you
have soldered all the pots you can fit the board to your front panel. Position the PCB at right
angles to the panel, the pot’s own pins will hold it fairly rigid for now. Then you can solder
each of the brackets. This will give you a very strong support and not stress the pot
connections.
The Alpha pots are labelled with an A or B suffix. For example: 50KB or 1MA. Alpha and
ALPS do the opposite to our European convention and use A = log and B = linear. So a 1MA
is a 1 megohm log pot.
The four front panel mounted LEDs must be fitted carefully if you are using the directly
mounted technique. Although this sounds fiddly, it's actually quite easy and it reduces wiring,
interference and possible errors.
A close up of the LEDs in a 19” rack mounted issue 1 TM3030. You can see that the LEDs simply poke
through the front panel.
Remove the front panel so that you just have the board again. Get the four LEDs and find the
cathode for each one. Make sure the cathode of the LEDs will go into the round pad, pin 2, on
the board. Carefully bend the LED’s legs at a point 6mm away from the plastic body of the
LED. The legs should be bent by 90 degrees so that the legs are pointing straight down.
Check to see if they fit into the board. The bottom of the LED’s body should fit just flush to
the board edge. Fit all four LEDs to the board but do not solder them in at this stage. Let their
legs poke through, there’s no need to cut them down yet. Now fit the front panel again to the
board and tighten the pot nuts. You should find that the board now fits snugly into position
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