d. Using the 200L-ma selection and assuming the X-ray exposure is exactly
200ma and the ma-shunt potentiometers are accurately adjusted, the following current
paths are used for ma indication.
From the ma overload on lead M1, is 200ma from the X-ray tube.
(2) Then the current flows through the meter M1 overload circuit to leads
M1A/Ma across the normally closed contacts of the mas-meter assembly.
(3) The circuit splits with a shunt current fraction going towards the ma-
The remaining current goes back to the ma overload circuit.
(5) The current returns from the mas-meter circuit on lead M to the ma
meter, to ground.
e. The shunt current flows as follows.
Across the normally open, now closed contacts MA/MSS7.
Across ma-shunt potentiometer P7.
To the 10-Ω, 2-watt resistor R5 to ground.
f. When the fluoro footswitch is depressed and a fluoro exposure is initiated, ma
through MA to M1A from the ma overload is as follows.
(1) The current flows across the normally closed contacts M1A/MA of relay
R1 of the mas-meter circuit.
(2) Then the current flows across the normally open, now closed contacts
MA/MSS1 of the 200L spot-film ma-select push button.
(3) The path then goes to the normally closed MSS1/MMF contacts
Re-4-SF on the spot-film changeover.
Then across the low-current meter shunt P6 and R6.
And finally, across the ma meter.
g. When a spot film exposure is initiated, Re-4-SF on the spot film changeover is
energized, closing the normally open contacts MSS1/MS1, and ma-shunt potentiometer
P7 is inserted into the ma circuit. The meter-shunt current is now through P7 and R5 to