Badly Needed: Fisher 552D Service Manual or Schematic

[Gen. Breckinridge]

Although the Fisher 550 series have been out of production for years the people I have talked to about getting a service manual or even a schematic act like they are protecting the keys to Ft. Knox. What give? I have a 552 that is sick and have a 551 for parts and really want to get the old machine up and running. I can't understand what the big secret is about old technology. I am a qualified electronics technician being retired from broadcast TV as director of engineering so I can fix it if I can get some info but as they say in the business, it's hard to drive through Kentucky without a road map.

If any of you have access to a service manual or a schematic I will be forever indebted to you. I have a users manual but it doesn't have the schematic in it. I will pay for copy costs and postage plus a little for your trouble. If you want to send the schematic alone with no return address that is fine. Whatever it takes, we will work it out. Thanks to anyone who can sneak one of these "highly classified documents" past security.

Ken Sturgill
P.O. Box 765
Marion VA 24354

 

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[LuckyLarry]

Actually Ken, those aren't really that hard to troubleshoot.

Start first by seeing if there is any sound, voltage to the exterior (search) coil, or any movement in the meter.

If any is present, then the next thing to do is to check for is voltage output where the cable plugs into the box. You should get anywhere between 3 dc to around 10 volts. If none is present, you need to troubleshoot the leads coming from inside the box at the circuitboard. If voltage is too high you know what comes next. If too low, then it's on to where the bad connection is.

Next, check to see if all transistors are operating correctly. After that the next thing is to check for deteriorated resistor values and good solder connections. If all that is good then check for micro or mini transformer blowouts. The rest is a walk in the park for any tech. Most other problems lie in cracked circuitboards and/or dirty/broken switches. If there is (near) correct voltage (TO) the searchcoil - look for a defective searchcoil.

Hope this helps.

LuckyLarry
(AKA "EasyMoney")

 

[marylandjack]

Fisher 551-D 552-D 553-D schematic and troubleshooting info

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

 

[SomerHimpson]

Schematics and troubleshooting guides for 553-d

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

Hi please, would you mind sending me the schematics and troubleshooting guide for the 553-D. Thank you.

Mike Prior

 

[beerguy]

I also started out my career as a bench tech. One thing I have found useful as a guide to metal detectors in general is the book 'Inside the Metal Detector'.

It was written by Carl Moreland, I imagine Lucky Larry knows him fairly well.

That book was great for getting used to the types of circuits that one would encounter while going through the circuits.

Also, Geotech is a great website for this as well. People post waveforms and discuss circuit characteristics in greater detail than I can absorb.

My focus was navigation and communications systems in aircraft, and I found the circuit functions in a metal detector to be quite simple.

A great opportunity to brush up on op-amp troubleshooting, comparator circuits and the like.