Bally S5500 MPU Dip Switches

[OldGuy]

New to all this, here is my situation that I need help on.  Acquired a S5500 that is set up for nickels.  Replaced battery, cleared ram and then received 31 error, that continues to come back.  This is based on the MPU dip switch set to .05.  If I change the switch settings to .25, then clear ram, the machine plays with nickels just fine.  The bill validator (IDO-44) accepts $1 but gives only 4 credits.  Here is my question (S):
Is the AS-1200 super hopper universal as far as coins are concerned or would it require a mod to process nickels?  The credits provided by the bill validator are they tied to the Dip Switch settings on the MPU? The game chips are for a 3 coin Diamond Winners.  Would like to leave as a nickel game, but have to solve the 31 error, every time I change dip switch to .05.  Any and all help appreciated.

[rslots]

Code 31 is a hopper error.  Is the hopper actually working when you have the machine set for quarters?  The hopper can be changed from nickel to quarter or vice versa by changing the disc mounted to the pinwheel.

[OldGuy]

rslots
Thanks for the response.  The hopper is functioning correctly.  Looks like not much difference between quarter and nickel disc, one with 15 pins and the nickel 16 pins.  What I can't figure out is why does it give a 31 error when I change the MPU dip switch back to .05 denomination and use the same hopper.  Sounds like the main difference is a piece of hardware not software related.

[OldGuy]

rlots
Got a little confused about hopper parts.  You were referring to the changing the shelf wheel and I thought you were referring to the pin wheel.  Can you tell me if the MPU dip switch controls the credits you receive when the bill validator takes in cash.
thanks again

[Badbaud]

Any time you change any DIP switch on a S5500 you have to clear the game.

[OldGuy]

Badbaud
Thanks for the input.  Thought I had done a clear ram when I changed the dip switches, but apparently not,  since it worked this time.

[rslots]

So is everything working now?  Can’t think of a reason why changing denominations via the dip-switches would cause a hopper error. The sole reason for setting the denomination via the dip-switches is for the bill validatior to know how many credits to give per dollar.  From a coin standpoint the machine would not need to otherwise know the denomination since it just gives you one credit per coin irregardless of the denomination. 

[OldGuy]

Yes, everything is now normal.  I couldn't figure out why I was getting a Hopper error.  Went ahead and changed the dip switches from .25 to .05 and did a clear ram and all worked as advertised.  Go figure.  But thanks all for the help.