Turn Tesoro Silver into Eldorado

[Tippy]

HI Folks,

I recall a while back a member describing on how to turn your Tesoro SIlver Umax into am Eldorado (Ground balance etc.) I have serched for this post and cannot find it. Any help would be appreciated.

Thank you,

Tippy

[Max]

HI Folks,

I recall a while back a member describing on how to turn your Tesoro SIlver Umax into am Eldorado (Ground balance etc.) I have serched for this post and cannot find it. Any help would be appreciated.

Thank you,

Tippy

Hi,
I never heard of this to be possible. I saw goodrat's mods description of of he changed a cutlass in a bandido...but it's not the same thing.

If something like this could be possible I'm interested too.
I'd like to change bandidoII in eldorato to gain the earlier disc model that eldorado has and seems to be effective more than bandido's disc on e.g. coinshooting and smaller items.
I've made some calculations but have really few time at now...so my bandido will remain the same for at least next 6 months or so.

Anyway, I remember that silver uses a different approach to balance so, if possible, could be not for everyone mod to do.

Best regards,
Max

[Esteban]

Compadre Sch. & mod.

Don't remember another modification, yes in Tesoro Compadre.

Collected from the old forum:

[Max]

Don't remember another modification, yes in Tesoro Compadre.

Collected from the old forum:

Hi Esteban,
many thanks. I'm really interested in tesoro's mods.

Best regards,
Max

[Esteban]

El Dorado

Hi Max

Found info of El Dorado.

Can anybody convert the dxf files in jpg or other image files?

[porkluvr]

Silverado

Here is link to an Eldorado thread, scroll down to Qiaozhi's post for a Eldorado schematic in pdf. https://www.geotech1.com/thuntings/s...light=eldorado


Here is Silver Sabre (plus) https://www.geotech1.com/thuntings/s...abre#post52186

I can't do this myself because I have a Silver Sabre II -micromax-. My detector's resistors look like ink spots. I can't show you a picture of the circuit board with points of interest circled, or before and after photos.

But if you a have a Super Sabre with a thru-hole board it seems to me like all you have to do is replace the Silver Sabre phase network with the Eldorado's. Use 82pf capacitors instead of 100pf.

Put about 6p8 capacitor across the feedback resistor on the recieve amplifier to delay the received signal about 4 degrees and regain the far CW end of GEB adjustment. You may have difficulty cancelling highly (-) mineralized ground if you don't.

The resistor marked 100k* can be reduced to gain better sensitivity to some less conductive metals like nickel and perhaps even gold, and iron.

My knowledge is mainly theoretical, so any feedback will be appreciated. If anybody tries this please let me know what happens.

Please don't attempt this unless you are confident in your ability to put everything back the way it was in case things don't work right.

[kt315]

why people think if Fisher and Whites RX coils has been connected to schematic Ground by one end, Tesoro coil CAN NOT HAVE the connect to Ground? what the problem is it?!
the very very oldie mistake pursuits the people by years

[porkluvr]

incomplete diagram

Whoa, hold on partner. The coils get connected same as usual.

My drawing is incomplete and I have left off a bunch of goodies, not because I'm changing the design but because, well, - I'm lazy.

[Max]

why people think if Fisher and Whites RX coils has been connected to schematic Ground by one end, Tesoro coil CAN NOT HAVE the connect to Ground? what the problem is it?!
the very very oldie mistake pursuits the people by years

Hi kt315,
is the old mistake, I agree. The circuit is ok, and RX coil is (one lead) in effects connected to gnd but not showed in some schematics. Connection, as you know, is made internally in the search head.
Without that connection I can't get my bandidoII working ok.

I post this information again for anyone that doesn't know that this connection exist and is required for proper operations, also if not represented in schematics.

Best regards,
Max

[Esteban]

Found this tips for Eldorado, think are valid for all classic Tesoro detectors.

[porkluvr]

update and correction

I've had a day to revue my hastily posted modification. The basic concept should be obvious, but I found a big mistake in my original diagram. Please, whatever you do, do not replace the 22nF capacitor in the
receiver with 33nF. I know it's unlikely anyone would have done so, but if you did, please change it back.

It's probably best to stick with 100k for the resistor marked 100k*. A linear taper DISC pot will cause the control to be scrunched up at the CW end. Use a LOG taper (best), or audio taper pot, to even it out.

Installing ~6.8pf capacitor in the receiver opamp feedback delays the receiver output relative to phase reference just about 4 degrees. (I couldn't sleep last night because this was bothering me SO BAD!)

Eldorado uses 5pf from DISC Zero Crossing Detector output to + input. This is (I think) to adjust for imperfect ~51/49 duty-cycle of DISC phase reference. Better to have slightly less ON time for the demodulator FETs, than more. (?!) Hey, the errors add up if you let them. The GEB ZCD doesn't need this because GEB duty-cycle is already less than 50%.

OK, we could still use more transmit power but this set-up should be better than what was before. No more factory preset GEB!
Good luck!