Version: 13. September 2004
17
[ ]R84 22K E2
[ ]R85 39K E2
[X] R86 SMD 0805
[ ] R87 3,3R F1
[X] R88 4,7R SMD 0805 E2
Diode D28 will be mounted standing up. The cathode will be bent back, the
body is placed where the circle on the layout is drawn.
[ ] D28 1N4148 D3
There is an extreme risk to destroy CMOS Transistors by ESD.
Use a potential free Soldering Station, at least discharge
yourself by touching a blank, metall ground plane before you
handle any electronical part
[ ] T17 BS170 MOS Caution ESD! D3
[ ] T18 BS250 MOS Caution EDS! E2
[ ] T19 BS170 MOS Caution ESD! E2
[ ] PIN33 E3
[ ] PIN34 E3
[ ] PIN43 E/F 1/2
[ ] PIN44 F1/2
[ ] PIN 8 D2/3
Test Building Group 4 (BG 4)
1. Visual inspection (see Section 1)
2. Resistance test (see Section 1)
[ ] Connect power supply as described at building Group 1 (BG1)
[ ] Connect PIN 7 and PIN 8
[ ] Connect headset between PIN 44 and ground
3. Smoke test (see section 1)
4. Functional test
Put the finger on PIN 33. You will hear a clear hum in the Phones. You may
measure the current during this test. Without hum it should be about
60mA. If you touch PIN 33 it may increase to as much as 150 mA.
Connect PIN 7 or PIN 8 of connector 4 to ground. If you tune up Trimpot
P6, you will hear the internal CW generator in the headphones.
Remove the power supply and the headset and continue with the next
building group
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