AVR+DSS Frequency Mod SD2100V2

[IBGold]

Jonn,
Did you get my PM? for a start check if you are getting +5 and -5 volts in relation to VB+ we will take it from there.
Regards, Ian.

[gef12]

Mario and All,

Sorry to hear about your plight with the PCB manufacturer. Hard to get good service these days. I often wonder how some of these companies stay in business with poor service. Keep me on the list for your board, whenever the situation gets resolved.


On my 2000, it looks like the only component that was changed was the IRF710. There was alot of the paint removed from the board also. (bet that was a real chore! hahaha)I talked with Woody awhile back, he recommended replacing the 2n7000 FET by the big CAPs, which I did. I did notice that the paint around the large CAPs was all yellowed so I ordered replacements for them. As I told Ian, the machine does nothing. The red LED just flickers once or twice when I turn it off. No sound whatsoever from the headset. I guess the next step is to go from the audio board test points towards the headset jack with a scope looking for any noise. I think putting any kind of speaker to the TPs would load down the circuit too much and not be fruitful. I would think that changing the tone and threshold should show some change at the TPs on the audio board. If so, that would be a plus. Maybe it's just a broken wire somewhere that is not showing itself to date.


v/r
jonn

Hi John
Those wires in the 2000 are quite feeble when moved around a bit .. so would check conectivity on them going from the boards to the front and back panels...
Gef

[Jiminy]

Ian, I finally got your email. Thanks. Did get the photo. I will check the +5 and -5v supplies. Will let you know the results.
/r
Jonn

[Jiminy]

Gef, thanks for the heads up and assistance. That was going to be the next step after checking the power supplies. I've already had one wire break, but that was the battery supply wire. Corrected that. Will keep on plugging. From your sig, I take it you are an amateur radio operator. I had a licence years ago. Advanced class. Didn't get to renew it in time so it expired. Most of my gear is REALLY old now. hahaha. Like me. . . . .

/r
Jonn

[IBGold]

Jiminy,

Most problems seem to come from broken wires when moving boards around with the 2000, I am also still a Ham but not that active any more and some of my equipment still run valves that give you an idea of my age Hi VK5KIB.

Regards, Ian.

[mario]

I got my boards!

And this time, I found no problems. I'll try to assemble a working unit by the end of the week.

[Jiminy]

Excellent. Can't wait to hear how they turn out!


/r
jiminy

[mario]

Hi Jiminy,

I am also excited about bringing this project to completion. I have been working months on this little board, and I'm looking forward to resuming my prospecting.

If all goes well I will hit those gold fields some time next week.

I have thought about my next project, considering that there maybe a way to reprogram that eeprom without removing it- you have to replace it initially with a reprogramable part of course, but once you have done it, it may be a simple matter of soldering some wires from my board and have the atmega flash it.

Still, I don't know if it may be worth it considering that we have not made our custom timings yet, so I'm leaning towards something else.

I don't want to say anything just yet, but it may be something most md users , not just us minelab guys, will benefit...

ill update you next time I have made some progress...

[IBGold]

Hi Mario,

Sounds good keep us informed I would like to see it capable of having from 1MHz to 4MHz capability for obvious reasons.
Jiminy did you receive the information?.

Regards, Ian.

[mario]

got it working

<iframe width="425" height="349" src="http://www.youtube.com/embed/jfPPs3EW6jo?hl=en&fs=1" frameborder="0" allowfullscreen></iframe>

I finally assembled my board.

With the exception of a minor error on the lay out (on the first pic, you can see a yellow wire jumping the wiper of a var resistor to a nearby component), the board works as intended!

I had a hard time soldering the AD9851 IC - I'm no fan of SSOP, but I didn't have any issues aligning pins. I will highly recommend a brand new soldering tip and lots of flux.

I like my modular design. I can now cut a separate AD9851 daughter board to fit inside the case to better cope with size constraints. I'm currently thinking about placing the main controller board inside my power unit (you can view that here). But, I'll likely create a separate control panel if i'm able to accomodate the whole board inside the case.




I haven't finished testing it. Nor have I written code for the higher frequencies used by the SD2ks. And unfortunately, I'm very time constrained...

[mario]

Sorry about the broken html code linking the video. I'm not sure how to get it working, so you may view the video here: link

To program the board, you will need a programmer. You can build your own using the schematic found here with this software: pony prog. Otherwise, you may purchase one of the many AVR ISP programmers found on ebay. Just make sure you find one with a 10 pin ISP header.

[Jiminy]

IBGold,
Yes, I received the information you sent. I've been out of state for the last two weeks and getting caught up in the office. Hope to start chasing voltages on the 2000 this weekend. Appreciate your assistance. /r J

[Jiminy]

Mario,
Board looking good. Looks like you have quite a power supply box there. That LiPo board, is that the one from MicroChip? I have one. Plan to use it to make a MD power supply also.

I have a Willem programmer that should suffice in programming the AVR as well as the 27C256.

Keep us posted.
/r
j

[mario]

Hi, Jiminy

I've rewritten the program to include software compatibility for the SD2000s.

Currently, to switch between modes, you'll have to toggle pin 27 (ground it for 1/3 of a second). I didn't think providing two separate binaries was necessary considering I could include support in the same program.

"SD2000 Mode" will give you access to the higher frequencies and scale the frequency steps better. To switch back to "SD2100 Mode," just toggle pin 27 again.

So far I'm still testing the unit. I would like to assemble another unit to solder up to my case, but need to order another AD9851.

Unless I find any other issues with the boards, I'll probably end up selling them for $10. I will only have 7 up for sale and will not make them again. If I do sell out and anyone wants one, that person may create a working unit from my posted schematic. I made several changes from my original prototype and will update it some time in the near future.

Now, regarding my power supply.

My lipo pack is rated at 8AH 11.2V. However, fully charged this thing gives me a constant 12Vs. Unfortunately, because I have to step down the voltage to 7.4V, the regulator gets hot. 12V->7.4V drop is a huge difference.

I have literately gone for days with out charging (while detecting 6-8hr/day), but I would discourage people from using such a set up. Other than needing a heavy duty regulator, you really want to avoid such a set up because of noise issues. Running the current through the regulator introduces noise to the system. So you want to draw your power from the source as directly as possible.

One of the Mods I'm considering involves digitizing the signal using a 20bit ADC. I have thought about feeding the signal to a UC3 (32bit AVR) chip for processing. However, because of the current noise issues, I will be lucky if I get 10 bits.

I will definitely need to clean up the system if I ever implement that mod.

[Jiminy]

Mario,
When you get ready to sell, I'll take two. Pls PM me with the details.
Is there a preferred parts list other than what is shown on the schematic?
Specifically which encoder did you use?
/r
j