Pentax EPK-i - Process Board (H700) Adjustments

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6.3 Iris
6.3.1 Iris replacement
1) The iris unit is located underneath Lamp Power Supply (LU1). Thus you need to remove Lamp Power
Supply first with the following procedures:
a) Remove Cove for power supply.
b) Remove Lamp Power Supply (LU1).
c) Remove Lamp Power Supply Tray by unscrewing the three screws. Then the iris unit is visible.
2) Remove the front panel by removing the scope connector handle first. And it is easy to access the iris
wire connector CN32 on Mother Board (E700).
3) Remove the iris unit.
4) Attach the new iris unit in reverse order of above.
6.3.2 Iris position adjustment
<Equipment>
For the iris position adjustment, the following equipment is necessary.
1) Extension card (ST-5031)
2) Iris positioning jig (ST-5503)
Note: Iris positioning jig has two sides. One is for adjusting the iris close
position and the other is for adjusting the iris open position (Refer to
Photo-11). To be held due to plungers on it.
3) Digital volt meter
4) Oscilloscope (100MHz)
<Procedures>
Connect the extension card (ST-5031) in order to access the test pins and trimmers on Peripheral board
(G700).
Note: The test pins and trimmers are indicated in Photo-14.
Caution: Pay attention to the connection between the extension card and Mother Board (E700), the extension card
and Peripheral Board (G700).
6.3.2-1 Hole element current adjustment
1) Connect the probes of the meter to TP31(+) and TP32(common).
2) Adjust RT7 so that the voltage attains +800mVDC+/-20mV.
6.3.2-2 Vref voltage – Close position adjustment
Caution: When you move the jumper, please do not apply force to the board. It may cause the board connection
failure and may cause a short circuit.
1) Move the jumper from 9-10 pin of P2 to 1-2 pin of P18.
2) Connect the probes of the meter to TP52(+) and TP53(common).
3) Adjust RT14 so that the voltage attains 0mVDC+/-5mV.
6.3.2-3 Iris position – Close adjustment
1) Set Iris positioning jig –Close side (ST-5530) to the iris
unit frame as shown Photo-12.
2) Turn RT8 counter clockwise until LD4 turns ON.
3) Slowly turn RT8 clockwise and then stop just when LD4
turns OFF.
4) Confirm if the edge of the iris plate just touches to the
face for Close position of the jig by eye.
6.3.2-4 Vref voltage – Open position adjustment
Caution: When you move the jumper, please do not apply force
to the board. It may cause the board connection failure
and may cause a short circuit.
1) Move the jumper from 1-2 pin of P18 to 3-4 pin of P18.
2) Connect the probes of the meter to TP52(+) and TP53(common).
3) Adjust RT13 so that the voltage attains -2.00VDC+/-0.01V.
6.3.2-5 Iris position – Open adjustment
1) Set Iris positioning jig – Open side (ST-5530) to
the iris frame as shown Photo-13.
2) Turn RT6 counter clockwise until LD4 turns ON.
3) Slowly turn RT6 clockwise and then stop just when
LD4 turns OFF.
4) Confirm if the face for Open position of the iris
plate just touches to the edge of the jig by eye.
5) To close the iris adjustment, put back the jumper
pin to the original position 9-10 pin of P2.
Photo-11 Iris Positioning Jig
Face for Close position
Face for Open position
Photo-12 Iris Position - Close
Jig
Photo-13 Iris Position - Open
Iris plate
Jig
Frame
Iris plate
Iris plate
Iris plate
Frame