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Testing the Trigger Switch on the RISO SP-275 ScreenFax

The following procedure should ONLY be done after contacting NEHOC for advice first. Any warranty will be void by the following action unless approved/ instructed by NEHOC prior.

Before we begin it's important to note that you can permanently disable your machine by damaging vital components inside the casing. The area which is covered below is not located next to the vital areas, however for protection we recommend keeping the front casing on the machine - this will keep the front circuit board covered.
1.  Disconnect the power cord and remove the machine from the power!
2.  At the top of the machine just behind the stage glass there are two screws holding the back cover to the machine (they may be under warranty stickers) - remove these
3.  On the side of the machine at the rear, there is a screw on either side holding the back cover - remove these
4.  Lower the lid and place your hand in the middle of the back cover plate and pull backwards - this should now come off easily.
If stuck wiggle the front casing a little from side to side to loosen and try again. These 4 screws are all that holds the back cover.
5.  Set the imaging dial to 0 and lift the dial upwards (gently) to remove from the machine
- (optional) you can also remove the power switch by simply putting upwards
6. With the back plate removed you can now slide the front cover forwards slightly to reveal the imaging switch at the back right rear of the machine (on the side) as pictured left.
The Stage Glass and Handle remain untouched - don't undo any other screws other then the 4 listed above.
As you will see, the Trigger Switch operates when the Trigger Arm is depressed - gently pushing the arm against the switch to activate.
It is normally the Trigger Arm which requires adjusting if the switch is sticking/ not connecting.
What the Trigger Switch should look like:
 On the right is what the Trigger Switch should appear like in the normal operation - the button is out and the Trigger Arm in position against the switch.
Trouble shooting:
If the button is in and the Trigger Arm is back so there is no contact then the Trigger Switch may be sticking
If the button is in and the Trigger Arm is against the switch then we need to adjust the angle of the switch

7.  Whilst looking at the Trigger Switch, lower the handle of the machine, just as if imaging a screen, so we can see what is happening to the Trigger Switch



It should depress and activate the button - you will hear a tiny click.

When the Trigger Switch is depress it will look like the picture left.






Making Adjustments

If the switch is not working there are a few thing we can do - try the following in this order.

Place a drop of WD40/ RP7/ mechanical lubricant onto the button ONLY - we are not spraying the button, just lubricating a little. This is preferred first as we try to avoid adjusting the switch angle where possible.

If the switch is not bouncing back then the pressure from the Trigger Arm might be too great and an adjustment on the Trigger Switch backing plate may be required


Adjusting the Trigger Switch Backing Plate

To the left of the Trigger Switch are two screws - it's the bottom screw that adjusts the angle of the plate.

As the Trigger Switch is sensitive, the degree of change is very minute and several attempts may be required before finding the optimum angle.

1.  Release the pressure on the top screw slightly - not too much as it's the bottom screw that does all the work

2.  Release the pressure on the bottom screw and adjust the angle

3.  Tighten the screws and test the imaging by lowering the handle and pressing to move the Trigger Arm

4.  Test the angle you have set by lowering the handle of the machine and performing a test flash (with the power off)

Testing the machine

With the adjustment made, we need to test the machine.

1.  Plus the power cord back in to give the machine power.

When we removed the back cover, we disarmed the power supply by exposing the rear safety switch, so when the power is plugged in the machine will still be 'dead'.

2.  Keep the back cover off at all times, however you will need to turn the machine on - either to PPC or NON-PPC (it doesn't matter). You will need to slide the front cover back for this to access the power switch.


3. With the power on we not need to power up the machine by enabling the rear safety switch - you can do this by simply pressing it in with your finger - pictured right

You need to keep this depressed whilst testing until after your machine flashes, as if you release the pressure the power is cut off.

4.  Once the machine begins to click 'OK' and ready for imaging, lower the handle and flash the machine

If the adjustment was correct you will receive a flash.


IMPORTANT - if you need to re-adjust the angle of the Trigger Arm again after testing with the power on - UNPLUG the power cord. Even through the rear safety switch disables the machine, you should ALWAYS use caution when handling high voltage electrical equipment.

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