Lakeshore Learning Materials 622 - Manual (Page 77)

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual
Options & Accessories 6-9
6.3 MODEL 6228 AND 6228-8MUX PERSISTENT SWITCH HEATER OUTPUT
The Model 6228 Persistent Switch Heater (PSH) Output Option provides a variable 0-124 mA DC output in 4
mA increments. The output compliance is an 8 volt minimum and the load can be up to 100 ohms. An MPS
front panel annunciator indicates PSH output current status. Model 6228 specifications are as follows:
Output Range: 0 to +124 mA Load: 100 ohms maximum
Output Resolution: 4 mA Off State Leakage Current: Less than 1 mA
Output Compliance: 8V minimum (8.7 typical at 124 mA)
The Model 6228 output current is present on a detachable terminal block with the I+ output on the terminal
towards the top of the board (1) and the I- terminal towards the bottom of the board (2).
6.3.1 Installation
WARNING
• This procedure is intended for trained service personnel who understand electronic circuitry and
the hazards involved. Do not attempt this procedure unless qualified.
• To prevent shock hazard, turn off the instrument and disconnect AC line power and all test
equipment before removing cover.
NOTE: With multiple MPS units, install the Model 6228 in MPS1 for proper operation.
The 6228 is factory-installed if ordered with a MPS or can be field installed at a later date. For field installation,
use the following procedure.
1. Turn off the MPS and disconnect the power
cord.
2. Locate the Optional Plug-In Board Slots on the
MPS rear panel. Remove the two screws that
secure a blank cover plate to the MPS rear
panel and remove the cover plate.
3. Slide the Model 6228 board into the MPS with the board handle towards the bottom of the MPS. Tighten
the two screws that secure the board to the MPS rear panel.
6.3.2 Model 6228 Operation
Access PSH Control from the MPS front panel.
Press Function Menu then Next Menu to display
Function Menu 2. If the 6228 PSH Option is not
present, <NP> appears next to PSH SETUP and the
associated function key is ignored.
Press the PSH SETUP function key to enter the
PSH Screen.
The cursor up and down keys move the line indicator ( → ). The ¥ icon indicates parameters changed only with
the Data Entry up and down arrows. Change all others using all the numeric entry modes, including the cursor.
HEATER: XXX mA
PSH Heater Current. Use any numeric entry mode
to change the value from 0 to 999 mA.
STATUS: <OFF> or <ON>
PSH Status. Use the Data Entry up or down arrows
to toggle the status.
LAST END: + 0.000 A
Last Current Setting. This value is the current setting when the PSH was turned off. This value is retained in
non-volatile memory so that the output current can be set to the magnet current when the PSH is turned on.
C A U T I O N ! S E T T I N G N O T S A M E A S S A V E D V A L U E
L A S T P E R S I S T E N C E C U R R E N T :
P R E S E N T S U P P L Y C U R R E N T :
E N T E R K E Y T O C H A N G E T O L A S T P E R S I S T E N C E
C U R R E N T , W A I T R U N U P D E L A Y , T H E N T U R N O F F .
¥ K E Y T O T U R N O F F A T P R E S E N T C U R R E N T .
E s c K E Y T O A B O R T .
H E A T E R C U R R E N T : 5 0 m A
1 0 . 0 0 0 A
5 . 0 0 0 A
2/3
OUTPUTS ONLY
LHe LEVEL
FIELD
PSH SETUP
P E R S I S T E N C E H T R S E T U P :
¤ H E A T E R
S T A T U S
L A S T E N D
O U T P U T S : *
+2.000A : 5 0 m A
: < H T R O N >
: + 0 . 0 0 0 A
+ 0 . 0 0 0 V