Fisher 550 series metal detector schematics/troubleshooting guides

I have recently obtained the Fisher Research Lab (FRL) schematics and troubleshooting guides to the following metal detector models: 551-D, 552-D, and 553-D. Please contact me if you need any of the information there-in. Especially if you need to bring one of these great machines back to life or back to factory specification.


New Member
Hello. I know this is ancient thread, but my 2 552-D Fisher detectors are ancient machines. I am searching for the schematics for these wonderful machines. Do you still have access to this information?