dead sovereign xs-2 pro

In considering this problem, have you looked at the concept that it may be a battery pack rather than a split power supply? My Garrett Groundhog uses 4 9v batteries. Two in parallel and two in series for a 9v and 18v power supply. Have you checked with Woody regarding schematics yet?

You are not allowed to view links.
Please Register or Login

He sells a power supply for most Minelab detectors that uses LiPo batteries. For all the time you have spent on this, you could have found gallons of nuggets if you had it repaired by him. Did you ask for a quote?

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,7722.msg59939.html#msg59939

Typical bloke if i break it like to try and fix it myself first,if all else fails then consult the guru.
Like to be out [detecting]too, dont we all.
Part of supply, as Frank shows on the schematics, is supposed to give regulated+&-5V from the 12V supply and is not.
pretty straight forward circuitry but being double sided and no schematics, going to take longer. 
   
Thanks again Frank for the info and the photo's.
My board has sovereign 6/96 rev3.2, software has rev1.1.

Have included photo of section, looks like U23 LM13600N drives FET gate.
replacing FET didnt fix it directly, but if the driver has failed would look at the FET too.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,7722.msg60364.html#msg60364

Bludger,
I opened up my older Sovereign and took a couple of photos of my board. That Board is a 2/91 Rev 2.3; apparently they went thropugh a lot of different layouts over the years! Interestingly, that board looks like it has the same basic driver layout as my later design schematic, but the reference designators are different, and the only surface mount parts on my board are the CMOS ICs. The driver FET (ST70A) on the board is Q7 (Q402 on the schematic), and it appears to be controlled by U24 (TL062CP) which is the same part shown as U1 on the schematic. The 2.5 volt reference diode is D1 (same as D403 on the schematic). Q7 is just above the two orange tantalum capacitors in the picture, U 24 is just to the right.

My board also has an LM13600N shown as U23, but I don't believe this is part of the basic power supply. It gets confusing trying to trace the parts on the board! You might want to re-check to see if you have a TL062CP part and if pin 7 connects to a FET gate; those are the two suspect parts. Also, let me know whether the TL062 is surface mount or through-hole dip package.

 A complete shot of your board would be cool for my reference files!
 
Thought that I would take the newer of my two Soverigns for a 1 hour walk in the park before dark. Very easy to get used to th3e machine again. Picked up $1.91 in US clad plus an amusement token, a button, and an aluminum piece probably from a bike. Dug quite a few caps and pull tabs, a few representative examples in the attached picture. I will get the second detector back together and try it out in the near future.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,7722.msg60416.html#msg60416

Bludger,
From your 012 picture it looks like U24 may be a TL062CP and U2 the FET? U2 is right next to pins 1 & 8 of U24 from what it appears. Check the voltage between pins 4 & 8 on U24 with the power switch on, and see if you get battery voltage. If so, that has to be the proper IC. If it looks correct, check the voltage on all pins of the IC. All the other layouts seem to keep the FET and control IC close to the output caps, so this would make sense.

Nice pictures, I'll put a copy on my hard drive!

If it appears that you need additional replacement parts, I can send you 2N7000 and TL082 parts which should be good substitutes for the originals. I happen to have quite a few of each. Large parts collection over 39 years in electronics as you can see!

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,7722.msg60756.html#msg60756

If Bludger trusts me with his control box, I would be willing to troubleshoot and repair it for the cost of postage. I would enjoy hearing that it is back in working condition! Bludger has my email address, I can send him my mailing address.

I pulled the control IC and FET from my older Sovereign tonight, socketed them both, and learned that the TL082 subsitutes directly for the TL062, but the 2N7000 has the drain and source leads reversed from the original FETs that qwere used in the Sovereign. Otherwise, it is a straightforward replacement. 
Bludger,
 I mistakenly posted  U2 as the pass MOSFET, it should have been Q7 ( ST70A on my old machine). If you replaced Q7 with the 2SK970, there may be an issue with the pinouts being different. The original part has the flat side of the TO-92 case facing away from the U24 IC, and has the attached pinout. The 2SK970 has a different pinout, as also can be seen in the attachment. You might try correlating the gate, source and drain between the replacement and original parts. I'm convinced that Q7 and U24 are the suspect parts.

If you are tired of dealing with this, email me and send it across the pond and I will attempt to repair it for free if you pay the postage both ways.
In an attempt to verify my schematic, I breadboarded tehe Sovereign power supply circuit so I could play with it without risk to my working detector circuit board. Things I found out about the circuit:

1. The loads are an essential part of teh power supply design. Because there is no DC return path to the center-tapped filter capacitors, a load across teh +5V supply and across the -5V supply to the capacitor center tap point is necessary to make the supply work at all. Then  =5V supply load is about 100 ohms, the -5 about 200 ohms for proper operation with a 12 volt battery input.

2. The typical battery drain at 12V input is about 55 milliamperes.

3. The +5V supply is essentially unregulated and drops by roughly 50% of the battery voltage decrease . The -5V supply remains in regulation until the battery voltage reaches about 9.5 volts.

4. The Sovereign is obviously not too sensitive to absolute voltage levels of the power supply, but this makes me wonder whether threshold settings change somewhat as the battery is drained.

5. The circuit was designed around the mid to late 80's I believe. The efficiency of regulators then was no so good as it is today. There was probably a decision to maximize the efficiency fo the battery pack by foregoing regulation of the +5V supply, and only regulating the -5V supply because that came free when creating the circuitry to incorporate that supply. Cost of the parts was also probably a consideration.

6. A dual output regulated supply would most likely improve performance at low battery levels. But it would require either a split battery with two regulators or a switching regulator with dual isolated outputs. Since the current drains are different on the two supplies, a split battery would mean that the batteries would drain unequally. That would make the more complicated design and a single battery the more desireable choice.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,7722.msg61060.html#msg61060