VOLTAGES AND PC-44 BOARD LAYOUT
The charts list the voltages and the location of the test
points. The values are based on a 120 volts, 60 Hz line,
shorted input, and no load connected to the output. All vol-
tages are with respect to circuit ground, except for
AC
heater
voltages—which should be measured from tube pin to pin.
Tolerance:
±
10%.
VOLTAGE
PICTORIAL CIRCUIT LOCATION
395 v. AC
T-3 Terminal Strip lug #3, #4
60 v. AC
T-5 Terminal Strip lug #7
+510 v. DC
C5 Capacitor lug #8
+505 v. DC
C3 Capacitor lug #4
- 80 v. DC
T-5 Terminal Strip lug #8
Tube
Pin #
8417 (Any) 7199
6N030T
1
1.87
290*
2
80*
—
3
500 30* 505
4 6.3 AC
502 6.3 AC
6.3 AC
505
5
6.3 AC
-26** 6.3 AC
6.3 AC
505
6
-26** .7
7
0
-
8
1.87
90*
505
9
80*
505
* Minor variations in current drain of the 7199 tube will
cause large changes in electrode voltages without detrimen-
tal effect on performance. Therefore, these voltage measure
ments are only approximate and may vary widely.
* * These bias voltages must be measured with a
TVM
or
VTVM
.
These measurements
must
be identical on all four 8417 tubes.
20
NOTE: When measuring voltages, it is important to take
volt meter accuracy into account. Most volt meters are spe-
cified for accuracy with respect to the range selected. This
means, for example, that a voltage reading on a ± 5% meter
could be off by
±
50 volts on the 1,000 volt range. In the
Mark VI, this could imply an incorrect indication when
measuring the high voltage
B
+, for example, which has been
specified ± 51 volts (with a 120 volts line). Even if the vol-
tage were exactly 510 volts, a ± 5% meter reading could
indicate a voltage from 398 to 602 and still be within the
specifications of both the meter tolerance and the voltage
tolerance. It is therefore necessary to always consider the
tolerance of
both
the voltage being measured and of the
measuring instrument.
