Velleman K4020, Manual

Page: 30 / 56

H4020-ED2-30
IMPORTANT: Check whether the soldering tips do NOT touch the heat sink!
Connect the thermal switch TS to the corresponding print pin connections on
the pcb.
IMPORTANT:
The MOSFET transistors are NOT yet connected.
Make the following connections to the bridge rectifier (see Fig. 4.0):
NOTE: All connections should be made with 1.5mm wire.
- Connect the + terminal of the bridge rectifier to the + terminal of screw
connector J1 using a piece of the supplied red wire.
- Connect the - terminal of the bridge rectifier (terminal diagonally across the
+ terminal) to the - terminal of screw connector J1 using a piece of the
supplied blue wire.
- Connect the remaining AC terminals to the AC terminals of screw connector
J1 using two pieces of white wire.
CHECK THE ENTIRE CIRCUIT THOROUGHLY ONCE AGAIN, SINCE THE
SLIGHTEST ERROR MAY DAMAGE THE EXPENSIVE FET TRANSISTORS.
TEST
Before mounting the amplifier blocks, we will test them one by one.
Due to the size of the circuit, the test will be carried out part by part:
1) Checking the power supply:
- Check to see whether NO connection of the MOSFET transistors contacts
the print pins.
- Connect the red, yellow, grey and blue wires of the 2 x 30V transformer to
the corresponding RED (red), YEL. (yellow), GR. (grey) and BL. (blue)
terminals of connector J1. (see fig. 4.1)
- Connect the transformer to the mains voltage using a slow 2A fuse (for the
time being use the supplied fuse holder) (see transformer box for the
connection of the primary).
- Check whether the four LED's (LD31 to LD34) of the power supply light up.
- Measure the voltages on the jumpers (these voltages are only meant as an
indication and may vary by a few volts with respect to the measured value)
as indicated on the print. The voltages are measure against the "LS-"
terminal of the speaker output (next to the relay).
- Remove the mains voltage and wait 5 minutes before carrying out the next
test, to allow the capacitors to discharge.