Barracuda Legend Kit Problems

[Impulse]

Ok i the coil has been wrapped in insulation tape and i have even stood in the middle of my garden with it beeping for no reason. When i turn the delay pot all the way to one end i get a click (end of the pot) then if i slowly turn the pot i get a BEEP (to signify the start of adjustment?) then after that i get a random BEEP then nothing and again a random BEEP then nothing for the rest of the adjustment.

[Old cart]

Sounds like you may have a bad delay pot. Try unsoldering it and with your dmm in resistance mode and it between the center terminal and one of the outside thermals. The resistance should vary smoothly as you vary the setting from end to end. If it jumps the pot should be changed.

[Old cart]

It is also possible that the damping resistor ( the one across the coil) is bad or the wrong value. Check this with your dmm. You can test inside just keep the coil away from metal. If you have an under damped coil it will ring and can cause these problems. Under damping is caused by the damping resistor being too high of value or a poor solder joint. They also can fail open due to too much current.

[Impulse]

ok i have just taken the pot off the board and it seems fine starts at 0.3 ohm upto 19.83K ohm.

[Impulse]

The damping resistor is 329.3 ohm

[Impulse]

If you have an under damped coil it will ring

when you say ring do you mean an audible tone from the coil?

[Impulse]

or do you mean like a half wave rectified 'ringing'?

[Old cart]

Ringing is a waveform that continues after a waveform transition. It is called that because it is a decaying sine wave: similar to a bell ring. You can not hear it but you can measure it when you get your scope.

[Impulse]

ok thanks i will order it asap, once i get the scope what or where should i connect it to? (i know sorry but i am still new to this)

[Old cart]

I looked at your picture again. Are you not using coax for your lead in to the coil? You should use coax and make sure the shield is on the ground side. Also coil polarity is important try it both ways,

[Impulse]

I will get some coax tomorrow and try that but i do not have a shield (yet)? also how does the polarity affect the coil as it is a mono loop 'bunched' coil?

[Impulse]

o and i have ordered the scope! delivery for wednesday!

[Old cart]

I will get some coax tomorrow and try that but i do not have a shield (yet)? also how does the polarity affect the coil as it is a mono loop 'bunched' coil?

The coax ground will do most of signal shielding. The coil may be polarity sensitive if there are significantly more windings on the outside of the coil they will act as "self" shielding. If the coil is just randomly wound the coil polarity itself may not make much difference.

[Impulse]

Hey old cart I have managed to get this it is a two core foil covered 1mm cable with a mesh shield any good?

[kt315]

Re: Eric Foster PI Search Coil Wire
Posted by: Eric Foster [ Send a Message ]
Date: November 25, 2012 02:15AM
Moderator
Registered: 10 years ago
Posts: 311
Hi Sven,
The orange cable is a specially made RG58 coax. It is made for the offshore industry, specially for underwater use, with a polyurethane outer jacket rather than pvc. This is much stronger and hard to penetrate by contact with sharp edges. Water at pressure would very quickly siphon along ordinary coax if there was even a small cut, and enter the coil windings. Salt water would write off both the coil and the cable and even enter the electronics unless a water blocking connector was used. Of course the orange coax is considerably more expensive, but I thought it was worth it as even for shallow water work it gives added protection.
Eric.