Hi Tesla,
The GS 4 is quite old but I will look to see if I have a manual. In the mean time, we can discuss the controls and what they do.
The main control box has 4 controls on top. There are three controls on the back of the main control box also.
Here is a brief summary of the top controls.
1. The DISCRIMINATION four position selector switch. This switch allows the owner to select OFF (ground balance off), ALL (detects all metals with no restrictions and ground balance is active), SEL1 which selects only some of the signals as determined by the setting of the G CAN DISC control which adjusts the ground balance as well as the disc feature setting when in the SEL 1 or 2 mode.
Now, to discuss the SEL 1 and 2, a little more, these two settings were designed to allow the owner to find certain English coins while ignoring most iron objects such as nails. These modes are sort of like the low conductor mode on the TDI where high conductor objects will be ignored. Select either SEL 1 or 2 and many high conductor objects will be ignored. Just what is ignored will be determined by the setting of the ground balance control also called the GCAN DISC
So, as a brief summary, the upper 4 position selector switch allows the operator to select the PI to be a straight PI with no ground balance, or select the ground balance feature, or select one of two disc settings that will ignore some objects while detecting others.
2. SENSITIVITY CONTROL. The Sensitivity control which sets the overall signal level, thus sets the basic gain of the unit. The sensitivity control simply adjusts the basic sensitivity of the unit.
3. The FOIL REJECT is the same as the delay control on most PI's. This control simply adjusts the delay as to when the sample is taken. Advance this control and small foil will be rejected as will be small gold.
4. G CAN DISC control. This simply is the same as the ground balance control on other PI's having a ground balance. The disc feature works somewhat like what happens on the TDI. When SEL 1 or 2 are selected, the disc control adjustment will set what conductivity of an object will be detected or ignored. So, basically, it allows one to select only a certain conductive level of the target. On the GS 4, Both the SEL 1 and 2 allow the operator to select certain lower conductive targets while ignoring other targets. Originally, there was only a SEL 1 feature but the SEL 2 was added to allow the operator to also adjust for a different English coin while ignoring iron objects.
NOTE!!!, when selected to SEL 1 or 2, certain objects will be detected and other objects will be ignored. Just what is detected or ignored will mainly be determined by the setting of the ground balance control (G CAN DISC control). The FOIL REJECT (the delay control) also has an effect but the main setting is set by the disc control.
On the back of the main control box (facing the operator) is a push button marked RESET that simply resets the threshold level to a predetermined setting. The design is such that this threshold will normally drift, so pushing the button could be quite common. In other words, to maintain the desired threshold setting, the push button is pushed which resets some internal signals and resets the threshold level to a set position.
Also on the back is a FREQUENCY control which adjusts the pulse rate and is adjusted to reduce noise from electrical interference. In other words, this control should be set to the position that has the least warble or instability in the signal.
The last switch on the back is one that selects between AUTO OR HOLD. This switch works in conjunction with the RESET PB to allow the operator to pinpoint a target easier. One can select the HOLD position and then push the reset with the coil partially over the target to reset the threshold back to the original level. This allows the operator to better pinpoint and object since the sensitivity is basically reduced much like what used to be done with earlier VLF's having a push button tuning. The normal operation is with the control in the AUTO setting.
There are two controls on the side of the rear control box and they are the THRESHOLD, which sets the PUTT PUTT setting from a very low tick tick type signal to a hum. The audio tone or rate of the putt putt signal will change frequency as the result of a signal change from a target or the ground if the ground balance is not set perfectly. With no signal present, the tone or PUTT PUTT rate is set by the threshold control.
The second control is simply a selector switch to turn the detector off or on. On some models this is a toggle and other models it is a selector switch.
On the front of the main control box is a switch that allows the operator to select between the main coil and a probe that came with the unit.
There is also a meter that simply responds to the signal level from a target or the ground if the ground balance isn't set perfectly.
That is a basic summary of the controls. If I can find my old operating instructions I will scan and post them.
Reg
