To read DC + Voltage
When making voltage checks in the unit, be ve is touched as 110V AC voltage is present also
ry careful where the probe .
1. The first test is to check the DC voltage pass transistor Q8. If any deficiencies are must be corrected before proceeding on.
s for the power supply and found in this area, they
2. The most important section in the keyer i Dash Divider, this will be checked as follows
s the Dot Generator and :
With the keyer shut off, connect a jump to ground. With the keyer set up in this man and dash divider can be checked at the same t paddles. Turn the keyer on. Connect the gro chassis of the keyer.
er wire from pin 8 of IC1D ner, both the dot generator ime without pushing the und lead of the VTVM to the
A. Set the VTVM to a 1.5VDC range and of IC2D. The meter should read about .16 an oscillating slightly. If these results are n C3, D1 and speed control.
touch the probe to pin 10
d the needle
B. of IC4A.
VTVM read +5VDC range and
Reading should be
touch meter probe to pin 5 dle oscillating slightly. obtained.
C. oscillate obtained,
Touch meter probe to pin 8 of IC4A.
rapidly between first check pin
1.5 and 2.5VDC.
Meter needle should proper results are not eedle should oscillate
between 3.6 to 4VDC at half the rate of pin 8. necessary.
Replace IC-4, if
Touch meter probe to pin 13 of IC4B.
Meter needle should
oscillate between . proper results are Replace IC-4, if ne
5 and 3.5VDC at 1/2 the not obtained, check pins cessary.
rate of test
14 and 3 of
E. Touch the oscillate from 1.6 pin 13 of IC3C for
meter probe to pin 12 o
proper re IC3C, if
f IC3C. Meter needle should sults are not obtained, check necessary.
3. Output circuitr generator and dashe for checking the ou
y: Since the jumper is s are being produced, we tput circuitry.
already installed in the bit 'll use this same approach
A. Touch the swing between .2VDC check resistor R24.
meter probe to the [C] and 2.8VDC. If proper Replace Q4.
of Q4. Meter needle should results are not obtained,
B. Touch the oscillate between . check R25. Replace
meter probe to the [C] 3VDC and .8VDC. If prop Q5.
of Q5. Meter needle should er results are not obtained,
C. Touch met needle should oscil obtained, check or
er probe to point [J] or late from .3VDC to .8VDC replace D4.
keyer output jack. Meter If proper results are not
e same procedure for Q6,
Q7 and D5.