Do absolutely everything required of you, and keep a running account of all money you get in, and all money you spend. You cannot have any "extras". Inability to pay is a defense, but it is hard. (You might try to find a local lawyer who will help you. The judge can give you credit for your jail time toward your fines so that you only have fees, and you may also be able to get the amount of your fees reduced.)
You don't have to be 18 to get a job. Start applying anywhere and everywhere. Make a payment toward your fines every month--even if you cannot pay the full amount. In some counties, the collections department has the authority to allow you to do community service in lieu of payment. This is something else you might look into. Keep working hard and you will get thru it.
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If your only issue is money then you are unlikely to be revoked. It is likely that your probation might be extended.
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Judge Chambers might make you do extra community service to pay those fines, if not then he will probably extend probation. Ask your PO if they can do a financial study on you.