I have practiced before courts in Maryland but my current experience is all in California. This is mainly a human question however. The quick answer is absolutely. Yes. The real answer is similar to what you probably tried to teach your children at an early age, which is to come tell you when they did something wrong. Every judge I have practiced before would tell your son something like, "If you find yourself in a position where you are unable to comply with any of the terms of probation, you need to come tell me about it as soon as you can. If you wait until you have missed a deadline, I will be far less forgiving." - Most judges appreciate honesty and earnest attempts to fix problems.
By your question, it sounds like he has already been violated. So, you already know the answer to this question. What I think you are concerned about is whether the judge will "find" him in violation and impose some penalty. Probation fees are not very high, and they are payable monthly. Usually, a year's worth of monthly supervision fees add up to less than what most lawyers charge to represent a defendant at a VOP hearing. Can your son pay or borrow the money to pay off these fees? What is his reason he has no income? Is he able-bodied? What has he done to secure employment since he was placed on probation? Couldn't he qualify even for part-time work? Yard work around the neighborhood? I believe P&P fees are in the $50/month range. That's not a lot. The judge is not going to be very understanding if your son shows up and has paid nothing, and cannot give a satisfactory answer to these questions. He should have a lawyer, however, as the possible consequences are jail, fines, striking any PBJ disposition he may have received, or extending the term of his probation.