Tesoro Golden µMax ground balance mod?

[Pinpoint]

First of all, I would like to know if adding a ground balance mod to the Golden uMax will improve the performance depth of the Golden in disc mode?

I am thinking about doing this mod, has anyone done this? I have read about modding a cibola and some other models for ground balance, would it be the same for the Golden?

[porkluvr]

What exactly do you mean by "this". Where did you read about this mod?

If you know where it is why don't you share that information?

[Pinpoint]

"This" mod = ground balance mod, as in the thread title .

I am trying to put the pieces together, I have read about ground balance mods of different Tesoro models throughout forums, here and there. This is the only link I could find that specifically referred to the Golden: http://www.treasurenet.com/forums/me...ce-tesoro.html


I have just found out that my Golden PCB is surface-mount.

[porkluvr]

... I would like to know if adding a ground balance mod to the Golden uMax will improve the performance depth of the Golden in disc mode?

You would need to solder a fixed 1k or 2k resistor between the cold end of your 10-turn pot and ground, to narrow the range that the pot covers. And, don't mess with the pre-set trimmer you are removing, just in case you want to put it back.

You might need to experiment with grounding your pot to the PCB and/or case, to avoid problems with your hand capacitance.

Without having the uMAX schematic handy, that's about all the technical advice I can offer except for one thing: If you know somebody who can do it for you and has already done it successfully, go that route.

edit: You can get better depth only if whatever you do makes it easy to adjust for whatever ground you encounter. If it is a chore and you adjust improperly, you will likely lose depth.

[Pinpoint]

From: http://www.treasurenet.com/forums/me...ce-tesoro.html

All you have to do is desolder the 3 trimmer pot legs from the board and solder wires in their place long enough to reach the 50 K pot you're putting in.

Once you desolder the 3 trimmer pot legs, where would you solder the wires? since apparently you only need two wires, and the Golden has a surface mount PCB.

The pdf that you can download here: http://home.earthlink.net/~puddlepirate/id13.html explains you only need two wires from the circuit to the potentiometer:

You will notice there are 3 contacts on the orig. trim pot as well as on the external
Bourns pot you will be using. Tesoro only uses two of the pots contacts. You may
ask why where there 3 trimmer contacts soldered to the circuit board? Two are
being used, the third was just soldered to a dummy pad that provides no function.

The problem is those instructions are for a Cibola that has through-hole PCB.

I just want to know where to connect the dots.

[porkluvr]

That Cibola is not a through-hole board, it is SMD. (Most all SMD boards will have
some through-hole components, or at least have wires soldered to through-holes.)

I don't see any convenient holes on your PCB like on the Cibola and if they're not
there, you would need to solder directly to the SMD pads.

If you look at your PCB with the trimmer pads forming an upside down Y I think you can
assume that the bottom left pad is CCW and bottom right is CW. The top pad will be W
(wiper).

I made that drawing showing equivalency just in case you don't find a dummy pad on
your PCB. Instead of being a dummy, the pad might be connected to the wiper - it makes no difference either way it's done.
So, you can indeed run only run two wires, one from W and one from CW, and leave CCW unconnected.

If there is not one already present, you should add a 1kΩ, 1/4W resistor like I show in my picture - that will serve to avoid grounding out the transmit reference signal if the dial is turned completely CW. That wouldn't damage anything but it can make a lot of noise come from your speaker. You'd best connect the resistor at the panel pot so you only solder wires to the SMD trimmer pads. Cover the resistor ends with some 3/16" diameter "spagetti", or heat shrink tubing, to make it neat and keep from shorting out. Or use tape.

Be advised that the circuits depicted in my picture is meant to be generic and is NOT
representative of the uMAX circuit.

[Pinpoint]

Thanks for your help, that makes sense.

I was told that with trimmer pots and potentiometers, the middle "thing" or the "odd one out" is always the wiper.

After a bit of research, I took it to an electronics expert to get the job done. I do not want to risk trying to solder on such a small circuit board.

The trimmer pot on the Golden has 100K written on it, yet advice from those who do this mod (even on the Golden specifically) is to use a 50K pot. The technician said if the trimmer pot is 100K than you would want to use 100K, not sure what's going on there. I could probably change it later if it's not right. If it's a 50K pot, then the pot will be 3/4 turn.

Thanks for your help along the way, this is good help especially for troubleshooting if anything happens with my Golden.

[porkluvr]

The trimmer pot on the Golden has 100K written on it, yet advice from those who do this mod (even on the Golden specifically) is to use a 50K pot. The technician said if the trimmer pot is 100K than you would want to use 100K, not sure what's going on there. I could probably change it later if it's not right. If it's a 50K pot, then the pot will be 3/4 turn.

STOP
Your man is wrong. My advise is to use 50K, and get the right one - 10 turns. The reason for that is that you will probably have too much slack in your pot's travel with 100k. That would mean that your desired adjustment range will only be a small portion of the total available adjustment and you will have poor resolution.

Worse, a 3/4 turn pot would be impossible to use.

Here's one possible source for a 50k, 10t pot.

There is a possibility that you could encounter soil that can not be balanced out with a 50k pot but could be with a 100k, but that is not extremely likely, so probably better to go with 50k.

[porkluvr]

Let me recant what I suggested. Go ahead and use 100k, 10 turns. You will definitely have all the adjustment range you need that way. Without knowing what your exact circuit looks likes I can't very well state with any certainty that substituting 50k would work satisfactorily without having to make some other adjustment. And I can't really tell you exactly what adjustment would be needed...

50k might be better, but only if your technician was knowledgeable enough to be able to tweak some other related component(s) in the GB circuit if needed.

Happy hunting!

[Pinpoint]

Help!

Alright, now I really need help.

I picked the control box up, took it home and now it doesn't work. All I hear is a quiet buzz in all metal and some quiet popping sounds in discriminate. The guy who did the job soldered on all three points and he even used the same coloured wires. I played around changing the wires around on the pot, but nothing changed. I ended up snipping the pot off.

In these pics, the control panel is tilted 1/4 clockwise:
You can see that he has soldered all three wires in place, the three red wires are where the trimmer pot used to be:


Could the electronics have been fried during the soldering process?

[Pinpoint]

I just air tested the unit, it seems to be able to function in that it will pick up targets, even at the same depths, just the sound coming through is very quiet and practically non-functional.

[satdaveuk]

Maybe its my eyes but if you look at the top of component marked 2587 theres balls of solder, maybe a short, also if you look further up again theres a splash of solder again could be a short, look by 1002 more solder thats just by looking at the picture, so look for bridges and hope you not buggered it up and yes there could well be fryed components.
Cant understand why you even attempted such a job without circuit etc on such a nice well made machine.

Regards

[Pinpoint]

Cant understand why you even attempted such a job without circuit etc on such a nice well made machine.

Regards

I didn't. I took it to whom I thought were professionals.

[Pinpoint]

Maybe its my eyes but if you look at the top of component marked 2587 theres balls of solder, maybe a short, also if you look further up again theres a splash of solder again could be a short, look by 1002 more solder thats just by looking at the picture, so look for bridges and hope you not buggered it up and yes there could well be fryed components.
Regards

I cleaned up some of the blobs of solder, they came off easy. The detector still gets good depth, it still works but the audio is hardly functional. It's as if the sound is trying to break through but can't.

Could it be the component that says "33n J100" that's damaged? It has markings on it from the soldering process that occurred in front of it. It doesn't look too bad, it looks worse in the pic, it's hard to get the camera to take better pics.

Could it be the wire that's soldered onto the CCW?

[satdaveuk]

I cleaned up some of the blobs of solder, they came off easy. The detector still gets good depth, it still works but the audio is hardly functional. It's as if the sound is trying to break through but can't.

Could it be the component that says "33n J100" that's damaged? It has markings on it from the soldering process that occurred in front of it. It doesn't look too bad, it looks worse in the pic, it's hard to get the camera to take better pics.

Could it be the wire that's soldered onto the CCW?

To be honest without a circuit your guess is as good as mine, it reminds me of another forum where this bloke who said he was a computer engineer stated repairing metal detectors was easy compared to his job and he was offering a repair service, well that made alarm bells ring because although he may be able to bull **** the average detectorist, but engineers like myself know dam well that without the data to go with these detectors your very limited to how far you can go repairing them, and hence why now people who have sent equipment to him are now up in arms because not only has he not been able to repair them there having trouble getting them back.
I do take the odd detector repair in as long its the old analog types but even then without the circuit to work with its very limited, and with these SMD type devices you need more than a bog standard soldering iron to make a job of it otherwise you end up with similar or worse to what you see in those pictures, like somones used a blow torch

Regards