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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
voltages—which should be measured from tube pin to pin.
Tolerance: ± 10%.
VOLTAGE
395 v. AC
60 v. AC
+510 v. DC
+505 v. DC
- 80 v. DC
20
VOLTAGES AND PC-44 BOARD LAYOUT
AC
PICTORIAL CIRCUIT LOCATION
T-3 Terminal Strip lug #3, #4
T-5 Terminal Strip lug #7
C5 Capacitor lug #8
C3 Capacitor lug #4
T-5 Terminal Strip lug #8
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
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.
Tube
Pin #
heater
1
2
3
4
6.3 AC
5
6.3 AC
6
7
8
9
* 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
These measurements must be identical on all four 8417 tubes.
+, for example, which has been
B
8417 (Any)
7199
1.87
290*
80*
500
30*
502
6.3 AC
-26**
6.3 AC
- 2 6 * *
.7
0
1.87
90*
80*
6N030T
—
505
6.3 AC 505
6.3 AC 505
-
505
505
or
.
TVM
VTVM
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