Models SRJ-7 and HRJ-7 Juno Survey Meters

SRJ-7
HRJ-7
2. TURN THE EXTERNAL ZERO CONTROL TO APPROXIMATELY 3/4 OF A REVOLUTION
FROM THE EXTREME COUNTER-CLOCKWI SE POSl TI ON.
Vt .
3. ADJUST THE INTERNAL ZERO ADJUSTMENT UNTIL THE METER READS ZERO.
MAINTENANCE
A. BATTERY REPLACEMENT.
ALL BATTERIES ARE CONTAINED iN A REMOVABLE PLUG-IN BATTERY PACK, TO
GAIN ACCESS TO THE PACK, REMOVE THE FOUR SCREWS FROM THE BACK-PLATE (NOT
THE BOTTOM PLATE). MOVE THE FILTER CONTROL TABS TO THE UP POSITION AND
REMOVE THE END PLATE. SPECIAL ATTENTION SHOULD BE GIVEN TO PLACING THE
BATTER] ES I N THEI R PROPER POSI TI ONS. THE I NSTRUMENT WI LL NOT FUNCTION
PROPERLY IF POLARITY IS REVERSED. REFER TO BATTERY PACK SKETCH FOR
BATTERY TYPES,
LOCATION AND POLAR1 TY.
THE 1.35 VOLT MERCURY CELLS (8-2) WHICH SUPPLY THE TUBE FILAMENT CUR-
RENT, WILL NEED TO BE REPLACED MORE FREQUENTLY THAN THE OTHER BATTERIES.
THESE CELLS MUST BE REPLACED WHEN IT BECOMES IMPOSSIBLE TO ZERO THE IN-
STRUMENT BY MEANS OF BOTH THE EXTERNAL ZERO CONTROL AND THE
CONTROL (ACCESSIBLE THROUGH A
8. ALPHA SCREEN REPLACEMENT.
HOLE IN THE SIDE OF THE CASE).
INTERNAL ZERO
THE ALPHA SCREEN, WHICH COVERS THE BOTTOM OF THE CHAMBER, IS VERY
DELICATE. IF THIS SCREEN IS TOUCHED, OR ALLOWED TO TOUCH A SURFACE BEING
MEASURED, IT MAY BE PERFORATED OR TORN.
REPLACEMENT SCREENS ARE AVAILABLE FROM TECHNICAL ASSOCIATES AND MAY
BE EASILY REPLACED BY FOLLOWING THE PROCEDURE GIVEN BELOW:
1 . REMOVE THE FOUR NUTS WHICH FORM THE FEET OF THE INSTRUMENT.
2. REMOVE THE BOTTOM PLATE AND SLIDE THE TWO FILTERS BACK TO EXPOSE THE
ALPHA SCREEN.
3. REMOVE THE TWO SMALL SCREWS ON EITHER SIDE OF THE METAL FRAME OF THE
ALPHA SCREEN.
4. SLIDE THE FRAME TOWARDS THE FI LTERS, THEN TI LT IT UP AND REMOVE BY
SLIDING TOWARDS THE FRONT OF THE INSTRUMENT.
5. THE NEW ALPHA SCREEN CAN NOW BE INSTALLED BY REVERSING THE ABOVE
PROCEDURE.
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