Plate Voltage and line Adjust Circuit Test

b. Depress pushbutton 3 -- MUT. COND.

d. Readjust the clamp (b above) until the

and vary the LINE ADJUST control so that

as voltages are within the limits specified (c

the multimeter indicates 130 volts

The

move) for the various BIAS control settings.

test set meter should indicate LINE TEST.

23. Plate Voltage and line Adjust Circuit Test

c. If the multimeter does not indicate 130

a. Connect a 375,000-ohm resistor (para

(TV-7A/U (serial numbers 1201

volts

0b) in parallel with the multi meter from the

through 9492), TV-7B/U, or TV-7D/U), ad-

cathode to the plate (pin 6 to pin 3) of the

just clamp A on R130 (fig. 30-32) until the

OCTAL test socket.

correct voltage is obtained.

b. Depress pushbutton 3 -- MUT. COND.

d. Depress both the 3 -- MUT. COND.

and vary the LINE ADJUST control so that

and 2 -- DIODE pushbuttons. The multimeter

The

the multimeter indicates 150 volts

should indicate 56 volts

test set meter should indicate LINE TEST.

e. If the multimeter does not indicate 56

c. Perform the following procedure when

(TV7(*)/U), adjust clamp B on

volts

the test set meter indicates below LINE TEST

R130 until the correct voltage is obtained.

( T V - 7 / U or TV-7A/U):

f. When the difference between the plate

(1) Connect the decade resistor parallel

screen

voltage and the high (130 volts

to R124.

grid voltage is greater than 30 volts or less

(2) Adjust the decade resistor so that the

than 10 volts, check both rectifier tubes. Be

test set meter indicates LINE TEST.

sure that all component defects have been

Note. The resistance should be between 2

eliminated. If the difference between voltages

and 15 megohms for the TV-7/U and be-

is still too great or too small, proceed as fol-

tween 1.5 and 20 megohms for the TV

lows :

7A/U.

(1) Reverse the filament-cathode leads at

(3) Solder a resistor of the correct value

the type 83 rectifier tube socket (pins

parallel to R124.

1 and 4), and recheck the plate

d. Perform the following procedure when

(para 23b) and screen grid (b above)

the test set meter indicates above LINE TEST

voltages.

( T V - 7 / U or TV-7A/U):

(2) If the voltage difference increased

(1) Connect the decade resistor in parallel

again or stayed the same, return the

with CR101.

leads ((1) above) to their original

(2) Adjust the decade resistor so that the

position and reverse the filament-

test set meter indicates LINE TEST.

cathode leads of the type 5Y3WGTA

Note. The resistance should be between

rectifier tube (para 2b) at terminals 3

40,000 and 60,000 ohms for the TV-7/U and

and 5 of T101.

between 10,000 and 100,000 ohms for the

TV-7A/U.

(3) Recheck the plate (para 23b) and

(3) Solder a resistor of the correct value

screen grid (b above) voltages. If the

parallel to CR101.

voltage difference increased or stayed

e . Adjust R134 (TV-7B/U or TV-7D/U).

the same, return the leads ((2 above)

to their original position.

(1) Determine and mark the midposition

(4) Replace the bias potentiometer (R129)

of R134.

with one of a lower value. A reduc-

(2) Adjust R134 until the test set meter

tion of approximately 100 ohms will

indicates LINE TEST. If the setting

reduce the high screen grid voltage

of R134 is approximately 45 to either

approximately 1 volt.

side of the midposition ((1) above),

Note. If R129 is changed, recheck the

check CR101 and R134.

plate (para 23b) and screen grid (b above)

voltages.

24. Screen Grid Voltage Test

a. Connect a 375,000-ohm resistor (para

25. Short Circuit Tests

20b) in parallel with the multimeter from the

a. Set the selectors and the controls to

cathode to the screen grid (pin 6 to pin 4)

HS5-3468, BIAS to 0, and SHUNT to 0.

of the OCTAL test socket.