RCA BA-13A - Page 10

7
VOLTAGE AND CURRENT VALUES
360 volts
T-2
PLATE
3
5.
->» TO R-IO
3
7 2
V
TO S-2
BUS GROUND
M-I45306-I
Figure 4 — Partial Schematic Diagram Showing Changes for Compensation.
Fuse Replacement
When replacing
i
o
65 volts de
72 volts de
1.8 volts de
90 volts de
48 volts de
1.5 volts de
Plate to ground
Screen to ground
Cathode to ground
Filaments to
ground
Meter Indication
Filaments
Plate Current
Screen Current
Second
stage
RCA 1620
o
y
B
>
ci
§
g
o
Q
5
O
<n
K>
Third stage
RCA 1622
<D
or
R-27 A
AWW-
5.600 JI
r-
a:
RCA-1620
V- 2
cc
ct
8
<O
d
o
o_
o
C-15 A
Hb
IMFD
— 11 —
0.2 3 MFD
Tubes and Plug-in Capacitors
Check the tubes for normal characteristics. Label
each tube, indicating condition and length of serv 
ice. Check the plug-in capacitors for leakage and
capacity.
C-8 1200 MMFD
nd nr T0 Cl3
I800JL I800IL
Voltage and Current Values
Voltage and current values for a
operating under normal conditions
following table:
A-C supply to amplifier — 1 17 volts, 60 cps
(A-C supply connected to the 1 1 5-volt tap on
traTsformer )
a fuse, make certain that the
replacement fuse is of the same type and rating
Plate Supply Voltag<
Total rectified current — 56 milliamperes
310 volts de
270
volts de
2 1 volts de
18 volts de
1 volt de
6.3 volts ac
45 ma
2.2 ma
18 volts de
1 volt de
6.3 volts ac
0.84 ma
0.22 ma
18 volts de
1 volt de
6.3 volts ac
1.7 ma
0.5 ma
First stage
RCA 1620
(1 ampere, Type MDL, stock number 53447) as the
one furnished with the amplifier. In emergencies
when this fuse is not available, a 1 ampere, Type
3-AG fuse can be used as a temporary substitute. Do
not use a fuse of higher rating for replacement
purposes since this will needlessly endanger the
windings of the power transformer.
the power
T
m I ■
S.
<0 ”
cc
u.
typical amplifier
are given in the
removing the amplifier from the receptacles.
This action automatically cleans the receptacle
contacts by the wiping action of the springs.
Plug the amplifier in and pull it out several
times to secure sufficient cleaning action.
d. Clean the step type attenuator in the MI-1 1233
amplifier. Press the catch nearest the rear end
of the attenuator, turn the rear-end cover
sufficiently to release it, and pull the cover off
of the attenuator. Apply Davenoil to the ex 
posed rear-section contacts, rotate the shaft,
and if any dark streaks appear wipe off the
contacts. Repeat this procedure until the con 
tacts are clean, then apply a thin film of Daven 
oil. Press the catch nearest the front of the
attenuator and remove the rear section of the
attenuator, exposing the front-section contacts.
Clean these contacts in the same manner.
Replace the rear section and the end cover
and lock each in place.