WWII SCR-625 Mine Detector

Repairs, Adjustments and Operation

The SCR-625 mine detector is a US WWII metal detector developed to locate metallic anti-tank mines.  

There are other pages or information on the AN/PRS-1, the AN/PRS-3, and the AN/PSS-11 mine detectors, EE-3, EE-8 telephones, TG-5 telegraph, Model 1914 service buzzer, BD-71 switchboard and residential phones, M151A1 jeep and other pages.

SCR-625 Repair page: https://sites.google.com/site/scr625/repairs

Recent sales of SCR-625 mine detectors on ebay:

https://sites.google.com/site/scr625/Home/iola--wi--military-show 

Detector models:

The two most common models are the SCR-625 C (and F), and the SCR-625 H. The chief difference being the older model C had the control box with meter mounted on the arm, while the later model H had a separate control box that attached to a belt.  The amplifier bag on the model C was slung over the shoulder, and it used a M-356 speaker as an audio indicator. The model H amplifier bag was a back mounted bag and used a HS-30 headset. Headsets and speakers are interchangeable. Above are pictures of the minimum necessary for a operational mine detector. In addition to the items in the pictures, be sure there is the wooden chest and an amplifier bag.

A working SCR-625 mine detector makes an excellent demonstration of WWII electronics technology that is a popular hands-on demo with older children, and would not be considered a weapon for school display. I have repaired seventeen SCR-625s, and other pages on this website detail what repairs typically need to be done. If properly repaired and adjusted, you should be able to detect a lightweight but large diameter metallic object at greater than one foot (30 cm). For demonstrations, I have found just 3 layers of heavy duty aluminum foil, 10 x 10 inches square (25 cm x 25 cm), is easily detected. It will not detect small objects like coins. All of them I have tried have a minimum amount of hum, especially at higher sensitivity or when using the headset. Originally they may have worked a little better, but age has taken its toll, and there have been no vacuum tubes (valves) of the type used by the detector made in over 50 years.

Any detector lying around for the greater part of 50 years will not work without repair and adjustment, but the technology is well within the expertise of any technician with experience in tube type radio or TV repair. I offer free advice and support for anyone wanting to repair theirs. See attachment at the bottom of the page for a video of one I fixed (with sound). A couple of short videos I have on Youtube:  https://www.youtube.com/watch?v=LtYr098snMA    https://www.youtube.com/watch?v=YtY_fqSVPFI

The SCR-625 requires a 103 volt battery and two “D” cells. Making a homemade 103 volt battery made out of a series of 9 volt batteries is well within the skills of someone with some basic woodworking handyman tools and some soldering experience. The biggest expense in getting a mine detector working is batteries, and you will need batteries before you have any idea whether the detector will work or not.

Army Technical manuals are TM11-1122 Technical Manual, TM11-4016 Repair Instructions.

Photocopies of these and other manuals can be purchased from: http://www.military-info.com/Index.htm or possibly found online.

I have a copy of the model H supplement of TM 11-1122, in Zip file format, that I can email (I think). It opens as .jpg scans of pages. Thanks to Bob R.

Always remove "D" cell batteries from any equipment not being used - they frequently leak and corrode equipment.

Caution when buying a Detector! A number detectors I have seen on ebay, and heard of, are missing the third piece of the handle! Be sure it has the piece farthest from the search coil if buying one!

May 2013 note - When inserting the 103 volt battery into the amplifier box, place the positive end in first, push the negative end down last.

Doing a demo:

The SCR-625 model "C" works best for demos, as the control box is part of the arm. I have a strap with a clip that goes over my shoulder and clip the amplifier box (without bag) to the strap.  This gives me easy access to the power switch in the box, and takes the load of the amplifier off the person using the detector. With me carrying the amplifier, I walk along the side of the person with the detector arm and search coil, with the M-356 speaker attached to the amplifier strap. With the speaker we both hear the output, and I can point out what is being heard or missing if he has  the coil too far off the ground. Be warned-the strap across your shoulder will hurt after a couple hours, and all day is a killer.

"What you do for yourself dies with you, what you do for others is immortal"

Contact me at dewnist@gmail.com  

"If it doesn't work, it's just spare parts"

A young man clearing a safe path for his family.