1. Try moving the searchcoil back and forth and forward and backward until you get the strongest audio signal. The target should be directly below the coil center.
2. If the audio response is maximum over a very large area, just momentarily push the Search Mode switch over to the Retune position when you are close to the target center. This will cause the target sound to shrink drastically, which will allow more accurate pinpointing.
3. You may have better luck at pinpointing if you try "X-ing" the target. Sweep the coil from size to side until you get the loudest response. Make a mental note of this point and then move to a position where you can sweep the coil at 90 degrees to the original position. Again, sweep side to side until you get the loudest response. Dig where these two lines intersect.

The Diablo has an automatic battery test sequence with each initial power turn on. To check the batteries simply turn the detector off momentarily and then back on. The detector should beep loudly for about 3 to 5 seconds, with the audio output loudness indicating the remaining battery strength. As the batteries age, this sound less intense, and fades out quicker. When you just hear a brief buzz, or no audio at all, replace the batteries.

To replace the batteries, pull the large knob on the battery door on the rear of the unit. The entire door will pop out. Remove the battery packs from the detector, and then remove the leads. Place the new penlight batteries into the packs, being sure that you observe the polarity indicators embossed on the insides of the pack. Slide the pack back into the detector, making sure the battery clip lead is connected to the pack. Install the battery door flange into the top of the cutout in the chassis, and push the nylon fastener into the hole at the bottom of the chassis, making sure that the plunger is still pulled out. Then push the plunger back in to lock the door in place.

Should you desire to do so, rechargeable Nickel=Cadmium batteries can be substituted for penlight cells. Individual AA size cells are readily available at most electronic supply stores, and well as the chargers for them, and they can be inserted into the standard holder used in your Diablo. The initial battery check reading will be slightly lower, but will not drop as much with use, until the batteries are completely discharged.

If the detector is to be stored for a long period of time, it is best to remove the battery pack from the detector. This will prevent internal damage to the detector if the batteries should leak.

The searchcoil is waterproof and may be submerged in either fresh or salt water. Caution should be exercised to prevent water from entering the chassis, where it could damage the electronic circuitry. After the coil is used in salt water, the coil and lower stem assembly should be rinsed well with fresh water to prevent corrosion of the metal parts. When used in the body mount configuration, you should not allow the cable connectors to be submerged. Several waterproof adapters are available through your dealer which will allow you to waterproof the connection between the searchcoil and extender cable connectors.

There are several good books to help the beginner learn how to use the detector, where to search and how to recover a target without damaging the environment. A good coin shooter can recover a lot of finds and leave the area looking as though he had never been there. Above all, always fill your holes when you have recovered the target.


TESORO Metal Detectors are sold through independent dealers, who are almost always treasure hunters themselves. They can provide you with you much needed information about how to use your detector, how to probe, plug and dig in your locale, and answer most of your questions about treasure hunting in general.

The use of earphones will benefit you in two ways. Most earphones will very effectively block out most of the ambient noise, such as traffic noise and wind noise, which will enable you to better hear the fainter signals caused by the deeper targets. Obviously, the older, more valuable coins will probably be deeper than the ones which were lost last week, so you should take advantage of anything that will help you hear the weaker signals. Secondly, using earphones will greatly extend the battery life, since it takes much less power to operate them. The Diablo is not equipped with a volume control, but does have a limiting circuit in the earphone jack. If less volume is desired with earphones, you may want to use earphones with a built in volume control. Any good 8 or 16 ohm set with 1/4 inch stereo jack will do.

Your Tesoro metal detector is covered by a Limited Lifetime Warranty, the terms of which are listed below. If your metal detector should require service, you may return it to the Tesoro factory, or tone of the factory authorized service centers. Contact the factory for the name and address of the nearest service center.

If you have any questions, don't hesitate to contact the factory.

This warranty gives you specific legal rights, and you may have other rights which vary from state to state.

This instrument is warranted to be free of defects in material and workmanship as long as it is owned by the original consumer purchaser. This warranty is not transferable, and is valid only if the warranty registration card has been completed and mailed within 10 days of purchase.

During the first two years, TESORO will, at its option, repair or replace any instrument covered by this warranty, without charge, except for transportation charges, at its factory in Prescott, Arizona, or at one of its authorized repair centers. After two years from date of purchase, TESORO will replace defective parts at no charge except a nominal labor change and transportation charges.

This warranty excludes batteries, damage caused by leaky batteries, cable breakage due to flexing on body mount units, and wear of the searchcoil housing. Also excluded are instruments which have been abused, altered, or repaired by an unauthorized party.

If warrant service should be necessary, contact the factory for nearest repair center.