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TDI 8usec mod...?
Posted by: Pawnbroker_Bob
Date: November 04, 2011 01:01AM
Does anyone have the procedure for the 8uS tweak? Please share..... Thanks!

Re: TDI 8usec mod...?
Posted by: TDIProUser
Date: November 06, 2011 01:30AM
I also would be interest in this mod and any other mod or specific setup that would give me an edge with my TDI. Thank You

Re: TDI 8usec mod...?
Posted by: Reg
Date: November 06, 2011 04:15AM
For all of the people wondering about this 8 usec mod, this is something that can be done only to one of the first 200 TDI's built. The TDI 8 usec mod can't be done on any of the newer TDI's. These early units are called the through the hole units, which refers to the components and how they are mounted. Later TDI's use surface mounted parts plus the adjustments are now done in software rather than by using regular components. Thus, only the original units have the internal controls that can be adjusted to reduce the minimum delay.

The way to tell as to which unit you have is to look at the conductivity switch. If the words GB on Required are directly above the Conductivity switch then it is one of the newer units. The original TDI's simply have the words High, All, and Low around the Conductivity switch and no other wording except the wording Target Conductivity below the switch.

Now, with that said, there is no other internal control that can be adjusted by the user. All other adjustments are extremely critical and any adjustment can and will screw things up, with some easily rendering the detector with severe problems.

Several of the internal controls require special special test equipment and detailed procedures to properly adjust the controls, so anyone who thinks they are going to tweak their unit will only degrade the performance if they touch any of the other internal controls. This is why there is little written about this mod. In fact, one of the controls require that control be set to one millivolt. That is one thousandth of a volt. This is something that can't be done with most test equipment. Other nearby controls are just as critical and require the settings be even less to assure proper adjustment.

At one time I considered providing the service to make this 8 usec adjustment for a fee, but decided against it. Also, once the adjustment is made people need to realize the detector will not act the same at the minimum delay. Because of badmouthing by a few "know it all" people I have elected to minimize any technical information I will divulge.

All internal controls are generally glued in position once they are adjusted and the factory can tell if someone screws with them. Now, with that said, one can't simply put any control back to the factory setting by trying to line up the glue pieces because of just how critical adjustments are. Without special equipment and knowing the procedures this is an impossible task to get things back to factory speck. Anyone who tries may think things are back to normal, but there will be some depth loss or some other issue to deal with once internal controls are adjusted. The worst case is the detector may not work or work so poorly it is rendered useless.

Personally, I if I were to decide to work on such units messed with by the owners, I would charge double to recalibrate a detector. This would amount to about $200 plus shipping if I were to decide to recalibrate one of the units. Because of the time and techniques required, presently I won't touch anyone else's unit at this time because of the time and effort needed to put things back to the correct settings, so please don't ask.

Reg

Re: TDI 8usec mod...?
Posted by: TDIProUser
Date: November 06, 2011 12:43PM
Hello Reg,

Thanks for the update and background on the mod. Your information was helpful and I do have one of the first 200 TDI because looking at my case it has the words High, All, and Low around the Conductivity switch and no other wording except the wording Target Conductivity below the switch. The words "GEB Required On" do not exist at all above the switch. Now whether this has been tweaked or not I can tell you the person I purchased from did not do this because he has no concept of electronics with the exception of using his Metal Detectors. I do not have the required test equipment to do this mod if I wanted to. I know you won't mess with a machine that has been tweaked out of tolerance or calibration, but I am asking what you would charge to make the mod to my original TDI?

I would also be interested in any information you might have on whether I could use previous coils on my TDI. I have in my possession several but of interest to me is finding out if the 9 " Gold Foot or the 6" Eliminator Coils from Magnum Force Search Head Applied reativeity Inc,, Philomath, Oregon will work on my TDI? I have used these on my Sprectrum with quite success.

Thank You
TDIProUser

Re: TDI 8usec mod...?
Posted by: TDIProUser
Date: November 06, 2011 12:45PM
Hello Reg,

Thanks for the update and background on the mod. Your information was helpful and I do have one of the first 200 TDI because looking at my case it has the words High, All, and Low around the Conductivity switch and no other wording except the wording Target Conductivity below the switch. The words "GEB Required On" do not exist at all above the switch. Now whether this has been tweaked or not I can tell you the person I purchased from did not do this because he has no concept of electronics with the exception of using his Metal Detectors. I do not have the required test equipment to do this mod if I wanted to. I know you won't mess with a machine that has been tweaked out of tolerance or calibration, but I am asking what you would charge to make the mod to my original TDI?

I would also be interested in any information you might have on whether I could use previous coils on my TDI. I have in my possession several but of interest to me is finding out if the 9 " Gold Foot or the 6" Eliminator Coils from Magnum Force Search Head Applied reativeity Inc,, Philomath, Oregon will work on my TDI? I have used these on my Sprectrum with quite success. Where I live here in the 49er Gold Country (Mariposa County) these coils would definitely be a big asset to me if I could use them.

Thank You
TDIProUser

Re: TDI 8usec mod...?
Posted by: parrott
Date: November 06, 2011 06:01PM
Howdy Reg... I'm the proud owner of an early "Hole" machine. It had been "factory reconditioned" by White's, and I've never had a problem with it. I only use it for nugget hunting in the Mojave desert where I have found it to run quiet with vertually no "electrical" interference, not even around the high-power lines.

I have have it about two years and don't mind about it having the "expensive" lithium batteries as they have not given any problems. But should I have a battery problem I understand that there is an aftermarket battery pack adapter available using AA batteries that can be belt mounted to the control box.

One thing I will mention, as it seems to work for me, I use the settings that Digger Bob recommended in the manual that came with my TDI; but I have found it best for me is to keep the gain less then halfway.

Also, I still use the standard 12-inch dual search coil and with a low gain it still has plenty of depth and also has a rock-steady threshold...

Lastly Reg, I thank you, Digger Bob, Carl and Greg M, for my modest success in finding a "few" nuggets with it while hujnting the caliche as found many areas in the Mojave desert... js.

Re: TDI 8usec mod...?
Posted by: Hobo lobo
Date: November 06, 2011 08:47PM
There is some one who will provide the necessary info to adj the pd to 8us.

Re: TDI 8usec mod...?
Posted by: parrott
Date: November 07, 2011 01:21PM
Hey Pawmbroker Bob... Careful, as Reg noted in his earlier post below, the 8us mod can be tricky. Also, you might find (as I have) using the 10us pretty good as it is. I have a "hole" TDI and at this point, I'm reluctant to have it done by other than at a qualified White's Factory service dept. Or by Reg who knows how to do it. js

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