The S+ will typically only accept coins up to the max bet, the only way to get more credits is by wins to credit or bills to credit. I believe the game chip that allows for tokenization will allow more than the maximum bet to be inserted as coins (they call it montana style credits, because I think in that jurisdiction, the insertion of coins does not mean you are betting and you cash out the coins you insert, in case you change your mind about it). From my records you would need game prom SP1137 and a set86 chip to configure the game that way. Some guys here use that combination to set the token value for 99 credits per coin (I believe that is the limit), so each coins provides 99 credits. It is a great way to avoid using a bill validator.