Page 6 of 31. Version 1.03 September 2012
Microbee Premium Plus+ | Construction Manual
Next we shall place all of the resistors and also the small signal diodes.
Referencing the marked up component overlay below, work through the resistors section of
the parts list which gives values & component reference designators, ticking off each
component as you go. The resistor SIPs (Single Inline Package) are 9 resistors in one
package with all of those resistors connected to a common pin. If you have a look at the
SIP, the value is written on one side (472 = 4.7K, 103 = 10K) and the dot at the left end
signifies pin 1. Make sure you line up pin 1 with the marking on the PCB.
Mounting the 11 x 1N914 / 4148 diodes is straight forward but make sure the band on the
body of the diode matches the polarity shown on the component legend.
Note also that one of the resistors gets mounted
at position ‘C18’. The Premium was originally
designed to have an LM386 integrated amplifier
as its speaker driver and C18 was part of the
coupling into the amplifier, however, the LM386
amp was very noisy – even when there was no
sound being output from the Microbee, so the
LM386 circuit was replaced by a basic one-
transistor speaker driver like the original
Microbees had. A 1K resistor gets mounted
vertically in the C18 position as part of this
circuit. See the photo opposite.
