If you served time in County Jail and were placed on Probation, it is possible to Expunge. If you went to state prison, you cannot expunge the conviction.
Seth Weinstein, Esq.
This reply should NOT be considered a legal opinion of your case / inquiry. At this time I do not have sufficient factual/legal documentation to give a complete answer to your question and there may be more to the issues you raised then I have set out in my brief reply.
First, CA does not have a true "expungement" process. Second, as the other posters have stated, if you went to prison, you aren't eligible for this relief.
Mr. Feasel is a former prosecutor in San Mateo County (CA) with over 10 years of criminal law experience. Nothing stated on this site shall in anyway be construed as legal advice, or as creating any attorney/client relationship. If you would like to hire Mr. Feasel to further investigate your situation, feel free to contact him thru this site.