Tesoro Cutlass II umax modifications

[kt315]

[Cadmaster375]

After all the mods I made I have been generally very happy with the detector and it's depth, but some days when it is warmer than usual I find the detector starts to give a lot of false signals. changing the battery makes no difference. all metal mode becomes almost useless and discrimination is very chattery with plenty of non-repeatable signals. it happens fairly often and the one thing in common when it happens is higher temps. all metal mode seems to be of less use more often than not due to noise. does my detector need to be re-balanced (the ground balance mod) or is it a heat problem. if it is a heat problem is there a solution? The air temps are from the 27 degrees centigrade to 33 degrees centigrade then the problems seem to be more common. the problems usually do not start right away and gradually increase as the day progresses. would adding heat sinks or cooling the box be of any use?

[FatBob]

That sounds like thermal problems. I haven't heard of those kinds of problems with the real original Tesoro units.

Maybe some component has gone bad due to age? The most susceptible part of the circuit is the transmitter. There is
a FET circuit there to auto adjust. The homemade ones sometimes eliminate that and have problems.

Chatter though would tend to come further down in the circuit.

This is a schematic that has notes for Cutlass II Umax;


The best way to find this is with a heat gun and freeze spray.
Heat it up until it fails then cool different components till it works.

It is possible Tesoro would fix it for you. They used to have a lifetime warrenty
and sometimes still fix things for free. You could call them and see what they say.

[Koala]

Interesting. Symptoms are right for faulty shield on the coil except its normally worse over wet grass not dry conditions.

[Cadmaster375]

Found a couple of bad connections on the coil connector one of which was the ground. the solder joint failed and it was only an intermittent connection and 2 wires wires are almost broken off. I had a lot of problems with that connector both with it's solder connections and preventing the insulation from getting fried when soldering. It was probably the hardest part of upgrading the unit. hopefully this is the last of the problems and I will only have to change the batteries when needed instead of diagnosing problems and fixing them.

[Cadmaster375]

discrimination works great but the all-metal mode still is falsing most of the time. Any ideas????

[Koala]

Post a video would help.

If its working in disc mode. But sounds in all metal mode as the coil approaches the ground then is suspect the ground balance is too positive.


Too negative and it would sound as the coil comes away from the soil but disc mode would normally be very flaky.

[Cadmaster375]

trimmed the wire and redid the connections yet again about a week ago and the detector is working like it was new. Have had no issues since.