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9) Connect the thicker blue and grey transformer leads to their solder terminals on the PCB.
Do not shorten these leads, but wind them around a pen to form a coil, these coils will
effectively suppress high frequency interference from the mains.
10) Now solder the thinner yellow and red transformer leads to the corresponding solder
terminals. If these are too long, also form coils and secure with a cable tie.
11) Slide a 17cm length of thin heatshrink over the remaining green and orange transformer
leads. (see figure 25) Now solder these to the terminals on the PCB.
12) Take the red LED from your kit and lengthen its longest termination with an 8cm length of
red wire. Lengthen the shorter termination with an 8cm length of black wire. Isolate each
solder connection using a 4cm length of thin heatshrink.
13) Solder these two wires to the corresponding PCB terminals, see figure 27.
14) Temporarily remove the small round fuse Z2 from its socket.
15) Mount mains switch S1 firmly to the front of the cabinet. Please ensure that the LED leads
are at a distance from the switch terminals.
NOW WE ARE GOING TO TEST THE POWER SUPPLY
1) Insert fuse Z1 (time lag glass fuse 5x20mm 250mA) and the spare fuse Z1' into the
fuseholder of the mains input terminal (both will be accommodated). Connect the supplied
mains cord between the amplifier and a mains outlet.
2) Switch on the power switch S1. The red LED must light up!
3) Switch off S1 and wait for three minutes (to discharge the power supply capacitors).
4) Meanwhile study figure 27. This shows some important details for testing.
5) Connect a volt meter (in DC voltage mode) to the "ff" measuring points. Switch power switch
S1 to the on position. After approx. 15 seconds the DC voltage meter should read 12.6V.
Please observe that this voltage increases almost linearly with time. The final voltage has to
be exactly 12.6V, and is adjusted by using trimpot P3.
6) Switch of S1 and again wait for three minutes.
7) Temporarily remove the mains cord and reinsert the PCB mounted fuse Z2 into its socket.
8) Connect your volt meter to the "Vo" test points. (in DC voltage mode, 200V range)
Reconnect the mains supply and switch on. After approx. 30 seconds your meter should
show approx. 200V. This voltage is not adjustable.
9) If you measure a substantial higher voltage (like 250V) it is likely that transistor T3 is faulty,
or the Zener diodes D14 and D15 are mounted incorrectly.
10) Also check the "24V" test points (meter still in DC-voltage mode), see figure 27. This voltage
is neither adjustable nor critical, even 28V is acceptable.
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