Sea Hunter XL-500 Pulse Coil Wiring

k, got the 60Hz on pin 6, and the two limiting diodes show 1.1k ohms both ways, i only read 135mV where the coil comes onto the board(it is disconnected), and i read 60Hz on the black coil wire, and 90Hz to 130Hz on the white coil wire. Also, my oscope does NOT show that signal form! mine is horribly ugly and all jacked up, send the pic in a sec.
Well, I had to go to the doctor last week for my back, apparently I injured it. Well, I went back this week, because it has gotten worse, sleepless nights, constant pain and such, well, my L4 and L5 are both shifted opposite of each other, one forward 5mm, and the other back 6mm, NOT GOOD. I have an MRI scheduled for Dec 6th, and a bottle of pain pills to hopefully hold me over until atleast then. Probably going to require surgery :( Anyway, I messed with it last night, and my progress is as follows:

k, i have reconnected the diodes, and the coil. My pulse looks kinda similar to yours, but not the same, definately. I will get a pic of the pulse signal today, when i can get up and moving.

thanks again for all the help thus far! :)
Did you ever disconnect the coil and see if it was being pulsed? I think you measured it while coil was in place?

All voltages looked to be good. We checked the Rail voltage 9.4 or so (Battery) The +5, -5 and all was good.

Please disconnect the coil and check again or use the scope. On scope you should see the 9.4 or so Pulse. Flyback voltage is going to be like 180DC Spike or more the other way. That circuit is using + ground. So the 9.4 should be Negitive and the Spike Positive.

If that all proves good the next step would be to check the limiting diodes and View attachment 56515 op amps.

LM709s are notorious for dying. Being your Preamp that would stop all signals down line.

There a pain in the butt to find any more. I think I may have one (Not Sure) ........
WOW'' You got your work cut out for ya Homefire....Looks like a (Mr. Bill Kit gone wrong)
Transistor upgrades?, VLF resistor implants, with a PI standard (factory) Im surprised the coil even
functions properly? I read the specs,but Im no pro when it comes too Tesero products. Those suckers are made to break. Good Luck...Tor


Well-Known Member
Ya never know if you don't try! LOL

No Mr Bill (I Wish) here but I know what works and What don't.

I have corrected simple problems on a many detectors that others have missed. Some of the Problems are left by the producer to correct calling them the Mark II!

A simple resistor and cap change could take a Garret Sea hunter detector from Commercial User Thing to Gold detector with the right coil.

Laugh All Ya Want!
I have recently acquired this machine, and just need to know if anyone on here can tell me what the solder points are for the coil wires, I have the Black and White wires already soldered on where they were before I disassembled the unit, but upon disassembly the red and green were not soldered to the PCB, so i have no way of knowing where they connect. Much appreciated!!


The coil only uses 2 wires not 4, two are extra and not used. A problem with these machines is the gold plated plug pins come unsoldered from there wires in the coil plug and in the machine plug if your coil is not working and there is no ohm readings check there. As with the wires only 2 of the 4 pins are used in the plugs.