If you salvage an old piece of equipment, you would debit cash for the amount received (if any), debit accumulated depreciation for the amount applicable to the equipment salvaged, credit Equipment, and debit Loss on Disposal of Equipment (if the amount received is less than the book value; or the amount needed to balance the entry is a debit). If the amount received is more than the book value, you would credit Gain on Disposal of Equipment.

Example: You salvage a machine and receive $50. It's original cost was $8,000 and its accumulated depreciation was $8,000. Debit Cash 50; Debit Accumulated Depreciation 8000; credit Equipment 8000; credit Gain on Disposal 50.