When I worked in Service Department at Rane Corp. we used 100% "extra strength" cleaning Ammonia to soak all the knobs and hardware. Typically 24 hours would suffice. To clean cabinets and chassis, Simple Green and Citrus Orange work well (be very careful on front panels, lettering may be damaged). Inner electronics would get washed multiple times with 10 - 20% Ammonia and distilled water solution, then rinsed multiple times with carbonated water (don't use Club Soda, it has sodium added). Carbonated water has added benefit the bubbles will agitate the sludge, tar and other deposits. Grille cloth on guitar / bass amp combos is one of the worst offenders for holding the smoke odor. Using a 5 - 10% solution of Simple Green and water usually helps deodorize grille clothe with added benefit of restoring tension to sagging threads. Clear vinegar can be substituted for Ammonia, using similar 10 - 20% mixtures with distilled water. Completely ridding a chassis of the odor can be very time consuming as cigarette tar is extremely pungent. Patience and elbow grease will serve one well. These procedures also worked well when we had to remove animal urine from units (it happened more often than one would expect). Dry everything with warm air a few times to be absolutely sure all moisture is removed, not only to reduce electrical risks, but to prevent corrosion.
