Anyone have a Broken XL Pro or 5900?

[d1g1man]

I have an idea for a simple mod for the XL Pro that should prove to be beneficial, can be cleanly done, but most importantly -cleanly undone!

As you XL Pro owners know, and I have mentioned in other posts about the XL the DISC control also doubles as the manual ground balance.

This control is quite touchy when setting it in TR DISC, and GEB NORM, at least for me it is. I am trying to gather as much information as I can before I open the case on the XL.

If it would physically fit, and I could find one of the correct resistance value I would like to try replacing it with a 10 turn potentiometer.

Perhaps one like this-
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In theory, this should allow a very precise DISC adjustment (like a rust iron nail on the surface, as Monte suggests) and an easier and more precise ground balance in the manual modes. Also, if you bump it with your arm, it would not be thrown that far out of whack. Having a numerical reference would also be handy as well IMO.

Sound crazy? or not needed? maybe. But it's still an idea I would like to explore and hey, you never know. It might be a good thing!

So, the question is. Does anyone have the specs to the potentiometers in these rigs? Or some busted up ones they could take a peek at?

10 turn pots are available all over the web. Using one off of an older White's box would be preferable though.

 

[thebeatmachine]

This idea isn't crazy at all. I would take the machine apart and test the one thats in there for its value . If Its a simple three prong potentiometer and not one of those double ganged ones it should be easy. Just keep track of what wire goes where and label them or write them. down.

Arn't those 10 turn ones expensive?

 

[d1g1man]

Thanks for the reply thebeatmachine. I am glad someone can "see" my idea. I have asked around. A ten turn from out of a 5900 would b $45.00 from a dealer.
I did manage to acquire a schematic, it says that it is a 100K. I'm not going to disassemble until I have the house to myself for the day. I want to take my time, take notes and I will even video the machine as I take it apart.

I was told by a certified White's tech that a ten turn will physically fit in there, it's just 3 wires (maybe even two) that connect to the pot.
The ten turn I have pictured above is a whopping $10.

While I am in there, I will measure the resistance of the pot, and of the gain control as well. Hey why not?

The whole trick to these older analog machines is getting the ground balance perfect, and the gain as high as it will go and still remain stable.

The DISC control, I am not too worried about, but it will be nice to dial in a number off a chart and set it to null or break up at any VDI number I choose.

There is also one fringe benefit. If you bump the control and turn it, it's not going to go too far out of tune. You can put it right back on the number you had it on to begin with.

I will update this area as soon as I have some results. I am just surprised there is not more interest in this idea.

This idea isn't crazy at all. I would take the machine apart and test the one that's in there for its value . If Its a simple three prong potentiometer and not one of those double ganged ones it should be easy. Just keep track of what wire goes where and label them or write them. down.

Arn't those 10 turn ones expensive?

 

[tab-nabit]

Perhaps you have an electronics supply located within your area. I used to hit a local HSC Electronics for some HAM radio gear. They had isles full of components, just amazing how much new and just loads of used gear I got at such reasonable prices. Electronics for such a wide variety of applications.

 

[d1g1man]

Oh man, that is so not fair. Anytime I need any gear I have to order it. I would go broke if I lived near a place like that!

I am only going to use first class, brand new components (uless this is not an option.)

My schedule is clearing up. Hopefully I can get to it soon. Thank you for the information, the more the merrier!

 

[Ed in SoDak]

Great idea! If the original pot is a double gang, you can replace it with two separate controls, provided there's a place to mount the second one. But it sounds like this is a dual-purpose single-gang.

But, I think the item in the pic is just a 10-turn knob and not a potentiometer, I have an old one that's quite similar. With one of these, you'd also need a 10-turn pot to go with it. You really don't even need the fancy knob, as any knob could rotate 10 times, but the counter would sure help keep track of position. The silver part attaches to the housing and is geared inside to advance the 10s, kinda like a car odometer. As long as you match the shaft configuration, you're good to go. Typically these have round shaft holes with a set screw, while many detectors are all over the park and could use most any kind of shaft style- big, small, split, half, setscrew, etc. If you go with a 10-turn pot, you can make sure it matches the knob.

You may be able to find a reduction-drive knob. They look similar but maybe larger diameter. On these, the inner shaft turns at a reduced rate. The reduction drive would work on a standard single-turn pot and may be the easiest way to go as you'd keep the original pot.

The black tab is a lock, so no more knob drift!

-Ed

 

[thebeatmachine]

I'm not positive that this is the right one. but here is a 10 turn 100k Potentiometer from Digi-KEY: You can get other values as well. It is 2 centimeters high so if it fits, Try it.



http://search.digikey.com/scripts/dksearch/dksus.dll?pname&site=us;lang=en&wt.mc_id=Dxn_US_T091_Catlink;name=SP534-100K-ND

 

[d1g1man]

Oh cool, thank you!

Hopefully tomorrow is the day to disassemble and take measurements (before I order parts).

Now the next big question is which cool looking knob?

Check them out, and give me you thoughts.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=262578&FV=fffc02b5

I like this one so far.

Or maybe this one.

 

[d1g1man]

Good news!

I finally found the time where I could sit down in peace to examine the internal components of the detector.
Disassembly was much easier than I had anticipated. It only took about 15 minutes.
There is only two connections, the polarized speaker plug and the head/meter to unplug from the board.


The pot is confirmed as being 100K in value, as it is stamped on the top in big white letters.
This was also confirmed by testing it with the VOM. (out of circuit)

In this photo you can see that it is a single gang/dual purpose pot.
It has plenty of room/clearance for a 10 turn of larger physical size.

This was a nice bonus, the pot connects to the board right on the edge. There is ample clearance to access for soldering. I will not have to remove the board from the enclosure to perform the mod.

So far, I think the hardest part to this is going to be which knob to choose to go on top.
Perhaps I will order all of them, and go from there.

I plan on taking resistive measurements for each graduation on the dial and in between.

This will provide a cross reference between the existing graduated scale and the new "digital" numerical value.

Now I just have to get my parts ordered!

 

[thebeatmachine]

Well fi combine the 10 turn knob with the 10 turn potentiometer, You will have to go 100 turns to get from one end to the other. IT may Take you half the day just to set it up. But you have found a lot of options and it looks like a fun prodject. I use JB Bond Weld or Goop Marine glue for the outside My MD projects. The Marine glue is a great seal and You can remove it if you absolulily have to. I

 

[d1g1man]

Well fi combine the 10 turn knob with the 10 turn potentiometer, You will have to go 100 turns to get from one end to the other. IT may Take you half the day just to set it up. But you have found a lot of options and it looks like a fun prodject. I use JB Bond Weld or Goop Marine glue for the outside My MD projects. The Marine glue is a great seal and You can remove it if you absolulily have to. I

Hi tbm. Let me clarify something.

Are you saying that the knobs I have posted here are gear reduced 10 turn knobs? If that is so, I am glad you spoke up.
I don't want a 100 turns!

This changes things. I would need to change the pot or just use the existing pot, and put on a 10 turn knob.

I will pull the data sheets on them and check them out. It may be better to just change the knob and keep the existing pot.

What do you think?

 

[rbholt80]

i have used the ten turn round style and it only turns 10 times. I used them when repairing ultra sonic pipe inspection units, I may have one in my parts bin i will look and see. Maybe i could send it to you so you can see how it works if i have it still. I did the 10 turn ground bal. mod to my cz6a years ago and love it.

 

[khouse]

I buy a lot of parts from Jameco d o t c o m or potentiometers d o t c o m

 

[thebeatmachine]

I was thinking, incorrectly, that the knob had a reduction drive. It doesn't You use it with a 10 turn Potentiometer like in the Data sheet like you suggested.

 

[khouse]

I mean your potentiometer. It's a 100k - 10 turn panel mount. This is another place I buy from. Very quick shipping with tons of parts.
Scroll down the page and you'll see it. Part # NTE 502-0109
http://www.action-electronics.com/pots.htm

 

[d1g1man]

Success!

The parts came in, went in. And it works exactly as I expected.

If it will quit raining for 5 minutes I will go out and try the manual ground balance.

So what do you guys think so far?

I might post a video demonstrating it if anyone is interested.

 

[a4wdguy]

I'm interested in a video, for sure.
So, if I understand correctly, in order to use the disc function, you have probably run the coil over a nail or somesuch and noted the number on the pot that the item comes in (or drops out) at. Is this correct?

 

[d1g1man]

Hi there a4wdguy, sorry it took so long for me to post a reply.

Yes and no,

Before removing the original pot I measured the resistance of the original pot half way between and on every mark.
I then took the same measurements with the new 10 turn and noted the numerical value stated.
With this information, I can emulate the original control by simply dialing in a number.

I also have taken coins (on paint sticks) and air tested, so I also have that information too.

In the photo above, it is set to 675. This is exactly where a nickel is fully accepted and everything below that is rejected.
One neat thing is that I can accept, break up (and to different degrees) or completely disc out a target.
It has really improved the resolution of the disc.

Also, using it in all metal mode or TR DISC I can get the manual ground balance PERFECT at max gain. I make note of the number, when I go back to the site I just dial it in and start hunting.

The little lock on the side has been really handy too, no more bumping the knob and throwing off the setting.

As soon as I have a sunny day I will get a video up.

Thanks!