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GTI2500 problem with 12.5" coil

A

Anonymous

Guest
Picked up a used 2500 with 9.5 and 12.5 imaging
coils plus a 12.5 scorcher coil. On initial air
test the 12.5 imaging coil did not like the
sensitivity to go above a 9. If you tried to drive
it to 12 then the detection distance dropped.
Now the coil detects constantly and will only quiet
down if you place the coil on the ground.
The other coils seem to work normally with air test
and coin shooting. Measurement of connector ohmmage
readings on the 9.5 and 12.5 imaging coils:
PINS***1-2***1-3*****1-4*****1-5*****1-6****1-7
9.5****230K**OPEN**9.85K**9.85K**689K**0 OHMS
12.5***247K**172K**9.98K**9.99K**316K**0 OHMS
I have checked the solder connections on the pcb
and on the connector and they look good.
Any feedback is greatly appreciated.
Bill Wireman
 
Due to the imaging these coils can go bad as they have much more sophisticated innards to go down. Since you checked the solder joints and other coils work fine..your coil itself may be faulty...A good jar or hiting a stump etc. can damage the innards..
Would even feel package being dropped during shipping or jarring along the way may or may not have caused a problem..
 
Burrowed an oscilloscope to check the coil
output and input signals with the following
results.
Pins 1 to 4 must be the xmit coil as the voltage measured
30 volts peak to peak at a frequency of 7352 hertz.
Pins 1 to 2 is for the outside rcv coil and measure 110-120
millivolts peak to peak at the xmit frequency.
Pins 1 to 6 is for the inside receiver coil and measure 30
millivolts peak to peak at the xmit frequency.
Next, I went to measure the 12.5 imaging coil and noticed that the detector was stable.
The only change was the removal of the cable clamp on the connector to allow hooking up the oscilloscope.
This leads me to assume that the clamp must be creating a short when the screws are tightened.
Oh, the voltage readings were similiar to the 9.5 imaging
coil readings.
I will probably just squirt a little rtv into the cable and let
cure before replacing the clamp.
 
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