The button opens THRESHOLD ( ON) and off (OFF) the TM 808 and adjusts the volume of the background or as it is commonly called «threshold».
If you turn the THRESHOLD knob to clockwise , the sensor opens (ON) and the batteries automatically check the meter (METER) for a few seconds.
To function properly the TM808, the test battery should appear in the upper area of METER is highlighted in yellow. In average temperatures , new batteries withstand approximately 12 hours of continuous use.
White’s TM 808 Manual
In cold climates , the battery life is shortened. The THRESHOLD knob must be adjusted for a little background audio or THRESHOLD that sounds continuously during the investigation.
The THRESHOLD knob should be adjusted so that it has a sound that sounds slightly. A lower setting is required when using headphones and a little higher without headphones , especially when used in an environment with a lot of noise . A setting in NORMAL is usually appropriate . Generally, the lower the THRESHOLD and hear a slight sound, the better.
The THRESHOLD may disappear when changing terrain , which indicates that you should press and then release the PUSH BUTTON on the handle to return or reset the sound of THRESHOLD.
This reset may be required at regular intervals , unless the AUTOMATIC THRESHOLD is in AUTO ( Auto) to automatically keeps THRESHOLD.
The setting SIGNAL BALANCE adjusts signal strength detector .
The NORMAL position works well for most cases research.
This setting provides very good performance with minimal interference from electrical sources.
If interference from minerals in the soil or from electrical sources (radio, power cords , etc. ) cause erratic behavior (large variations in the background audio ) or create difficulty in regulating GROUND BALANCE, then the button SIGNAL BALANCE should be set slightly more towards side of the clock to the (+ ) .
But be very careful when it rises above NORMAL. If the detector operates erratically due to the use of many (+) , his response to targets located at great depth will decrease. Even if the GROUND BALANCE is not configured correctly, the SIGNAL BALANCE overloads radio signal detectors and reduce the depth of detection.
The best setting is that which results in smooth operation, while allowing them sound clear objectives that are in depth , and achieves the GROUND BALANCE with a reasonable degree of difficulty.
If service tools is unstable , you must set the SIGNAL BALANCE slightly toward (-).
For best results, the adjustment GROUND BALANCE must be adjusted each time according to the probe used .
The setting NORMAL works well in most cases.
The GROUND BALANCE adjusted to exclude or ignore the usual minerals found in the soil and thus allows the deepest possible penetration . A setting in clockwise to the (+ ) is used to having more minerals and a setting unlike clockwise to the (- ) is sufficient land with few minerals.
The method for adjusting this setting will be discussed in Section TUNING ( Set Up) .
In short, when the GROUND BALANCE configured correctly observed little or no change in the sound of THRESHOLD, and upload or download while the detector relative to the ground .
It should also be noted that the setting AUTOMATIC THRESHOLD, for peer will talk in the next section, must be set to NO-AUTO ( Manual) as adjust the GROUND BALANCE.
The settings GROUND BALANCE and SIGNAL BALANCE operate together to exclude adverse reactions and provide the deepest possible penetration (depth of detection) .
Setting AUTOMATIC THRESHOLD is used to activate (AUTO), or disable (NO-AUTO), the reset of automatic audio background .
This feature provides automatic maintenance of the background sound .
When the AUTO, allows the background sound to the detector remains smooth or constant regardless of the small changes in soil minerals , or the upward or downward movement of the electronic signal . When using NO-AUTO, the changes in the sound background that are normal for such tools require manual reset ( pressing and releasing the PUSH BUTTON to handle) .
WARNING: The detector must Anakin when we use the position AUTO. If we are still over the target, the target signal will disappear.
In place NO-AUTO, the AUTOMATIC THRESHOLD does not work. Use this position when adjusting the GROUND REJECT ( Reject ground ) to make up for the ground.
Used in search function if the content in minerals of the soil does not change quickly though there is little interference from radio signals , etc.
In NO-AUTO position detector need not be moved when it passes over the target . You stand over the target without the signal disappears .
It is useful for locating the center of a target located at depth.
When using NO-AUTO position needing to press and release the reset button located at the tip of the handle at regular intervals, so that the sound background to remain stable and unaffected by the upward or downward movement .
If the sound background gradually increased or decreased during the investigation, press and release the button to return the detector to normal background sound . This requires skill and experience.
Most users will have to operate in AUTO until you gain some experience.
The PUSH BUTTON ( push button ) located at the tip of the handle.
Used in NO-AUTO position to reset the background sound when moved up or down.
Makes manually work the AUTO position automatically . Still used in detection.
When press and let the PUSH BUTTON and the detector is located above a target, the signal intensity will be reduced in helping to identify the center of the targets.
As will later say , the PUSH BUTTON also used to reset the sound of the background by setting GROUND REJECT. When you press and release the PUSH BUTTON, do slowly.
Leave it , hold it for a second and then leave it for best results.
The speakers are automatically closed when placed headphones. Maximum detection depth and longer life for the battery achieved using headphones .
Most ; typically 8-100 ohm headphones work well with this model . It does, however , cable stereo jack so required with stereo headphones or those with Stere switch to sound the signal on both handsets .
1. Set the SIGNAL BALANCE and GROUND BALANCE to position NORMAL. Set the AUTOMATIC THRESHOLD in position AUTO.
Two . Turn the THRESHOLD to clockwise and check the meter to determine the conditions of the battery (must be 75 % or more to operate the detector ) . The setting THRESHOLD, at this point , must be readjusted for a very faint sound. The detector will work well (it detects metals) in most parts of the settings in these options. However, for optimum performance and penetration depth , requires good adjustment GROUND BALANCE and SIGNAL BALANCE.
The procedure for the GROUND BALANCE
Three . Set the AUTOMATIC THRESHOLD in place NO-AUTO. Warning : Stay away from metal objects ( cars , pipes , steel structures , etc.). Remove anything you have metal on you (band , car keys , watch, knife , etc.).
4. Hold the tool at hand to the side like you’re holding a suitcase (about 50 inches off the ground). Press the PUSH BUTTON located on the handle, hold it for one second and release. You will hear the sound of the background . Lift the tool about 15 inches from the ground. If the sound THRESHOLD little or no change , the initial setting of the NORMAL GROUND REJECT is sufficient for research in this area . Put the AUTOMATIC THRESHOLD in the AUTO position and continue the investigation.
5. But if the sound of THRESHOLD change as you lift the tool , leave the regulation AUTOMATIC THRESHOLD in NO-AUTO position and proceed to customize it to the ground in the following way:
Procedure for Ground Balance ( balance of soil)
A) If the level of THRESHOLD decreased or disappeared when you pick up the tool , turn the GROUND BALANCE slightly unlike clockwise to the (-).
Lower the tool within reach , press and release the PUSH BUTTON, and lift tool again another 15 inches off the ground while listening to the sound of THRESHOLD. If the THRESHOLD continues to decline or disappear , then repeat this process until the level of THRESHOLD be about the same when lifting the tool about 15 inches from the ground.
B) If the THRESHOLD level rises or make sound when lifting the tool, then you need to do the opposite process than that described above.
Adjust GROUND BALANCE slightly clockwise to the (+) . Lower the tool within reach , press and release the PUSH BUTTON, and lift tool again approximately 15 cm watching any changes in the sound of THRESHOLD. Again these procedures (A and B) must be repeated until the level of THRESHOLD change little or not at all, as you lift the tool another 15 inches from the ground.
C ) Remember to press and hold for a second and then , to let the PUSH BUTTON is on the handle after each adjustment you make to the GROUND BALANCE while holding the detector within reach like it’s suitcase .
Determine if the sound increases or decreases when you lift the detector about 15 cm from the ground and make the appropriate corrections to the GROUND BALANCE. Lower the loop and press and release the PUSH BUTTON. Continue this process until there is little or no change in THRESHOLD when lifting the detector.
D) The procedure for the GROUND BALANCE is important as setting the SIGNAL BALANCE turns to the (+) . The setting SIGNAL BALANCE need not exceed NORMAL for most investigations.
If you can not set the GROUND BALANCE as we said above, try to go to another location because maybe you ‘re over buried metal object.
If the problem persists , turn the SIGNAL BALANCE slightly unlike clockwise to the (-) and try again.
The maximum detection depth (maximum penetration) can be achieved by setting the SIGNAL BALANCE in certain circumstances, as shown by the smooth and stable operation , and the ability to adjust the GROUND BALANCE.
If the GROUND BALANCE is suitable to NORMAL or if you can easily find the right setting for the GROUND BALANCE, you might want to turn the SIGNAL BALANCE slightly clockwise to the (+) . And repeat the steps for the GROUND BALANCE.
This ensures optimum adjustment SIGNAL BALANCE for specific conditions , and therefore the maximum detection depth .
The AUTOMATIC THRESHOLD should revert to AUTO once the GROUND BALANCE.
The volume will increase and the meter will indicate a very high when the tool passes over buried metal object.
When the target is close to the surface, perhaps counter reaches the end and the volume will increase to maximum.
Remember when you are looking to position AUTO, the detector must be moved when trying to find the center of the target.
If the detector stops over the target , the audio signal will disappear. Cross the desired area from at least two directions observing the area where there is a louder sound and greater meter reading . This process over the target locates the center of the target .
When Refer position NO-AUTO, a target on the surface may seem to be very large . This is normal.
The aim should be curtailed to determine more accurately the location.
Pass over the target area by at least two different directions.
When the counter reaches the end , momentarily press and release the PUSH BUTTON. Continue to pass over the target by pressing and releasing the PUSH BUTTON several times.
Sometime the meter will be on top and the sound of the speakers also will peak and then will begin to decline. In this loop , the front peak is above the buried metal object.
If you press and release the PUSH BUTTON as the target is below the loop will reduce the signal and locate the target more easily.
When using NO-AUTO, the PUSH BUTTON is needed to locate the target, while in position AUTO, AUTOMATIC THRESHOLD function detects it automatically.
The most efficient way to search an area is to use a grid pattern over the selected area .
Try the grid lines are not more than 1.5 meter.
Spend many times over in one direction , then turn 90 degrees and Recoat on top to ensure that you do not got a buried object. The aim is usually located under front loop or antenna .
Sometimes more deep targets located closer to the rear of the tool. Usually there are more than 9.10 inches from the back of the front loop even to aim at a very great depth.
Determination of the metal depth
Once you locate the center of the target, the average depth where the target can be determined using the following method triangulation .
1. Move to one side of the detected center of the target.
Two . Set the AUTOMATIC THRESHOLD in place NO-AUTO. Press and release the PUSH BUTTON located on the handle while holding the tool at hand.
Three . Move directly to the point of stopping when the target react first. At this point , the distance from the front center of the loop from the front or antenna to the point where the target is detected about the depth to which the metal in the soil .
Caution : This method gives an approximation of the depth of deep targets. May not work well in most shallow and big goals .
1. Water can damage the tool. The TM 808 is not waterproof , but just water resistant. This tool should protect it from rain and from immersion in water.
Two . Clean the control box and antennae with a damp cotton cloth. The wax on the car or furniture can be used to polish the tool if you wish, however, to only use cotton cloths . The tool should be cleaned after heavy use near the beach with salt water. The warranty does not cover cosmetic imperfections due to wear or exposure to the sun or salty air.
Three . The heat and cold have a negative effect on your detector . When you’re not looking , let your detector in the shade. When I leave the car and it’s hot , to cover it with something to protect it from direct sunlight. Save your detector indoors in a heated area during the winter months , having pull the batteries from the control box and battery tray .
4. Observe the front and rear antennas not be bent during storage or use. These are precision pieces . The operation and performance can change significantly from their natural shape and dimensions.
5. The base of the battery requires attention with respect to time and use. If you have removed the battery from the base , use a screwdriver or a nail file to clean any residue contacts inside the base or the contacts on the cap. The contacts on the outside of the base of the battery may need to be cleaned if you see residue.
Some C-size batteries sold in the market today ( less common are rechargeable C) did not have adequate natural length to work well at the base of the battery. To compare the length of the standard battery of this rechargeable or battery is not brand before purchase. If you notice problems immediately after changing the battery, try a different battery type before continuing.
Do not use lubricants on any part of the detector !