Silverdog Surf PI Modifications

[multieagle]

I wanted to upgrade my working Surf PI. Perusing various Geotech posts I came up with the following modifications suggested for the Silverdog Surf PI 1.2:



C5: Replaced 470nF with 220
C6: Replaced 470nF with 220
c8: replaced 100nF with 47nF
R2: replaced 3k3 with 5K variable pot
R9: replaced 1M resistor with 1M pot
R16: replaced 220K with 470K
R17: replaced 220K with 470K
R20: replaced 22k with 47K
R22: replaced 100K with 220K

Initial Testing Front End
Battery charged 11.47V
NE555 Voltage readings
1: 0
2: 5.20
3: 11.43
4: 11.45
5: 11.43
6: 5.21
7: 5.90
8: 7.59

7660

1: 1.42
2: 2.51
3: 0
4: -2.37
5: 4.99
6: -4.76
7: 5.20
8: 6.70

Questions:

1. Is a bit of a stretch to include all suggested improvements (modifications) and expect a working board? Would it be better to add one at a time, and proceed in same manner for all mods?

2. Is it possible to test front end values prior to installation of remaining potentiometers?

3. Are the voltage values for the unmodified Surf PI similar to the Pro?

I have not attached all the Geotech references. The Surf PI was/is my introduction to electrical kits. It was slow slogging and I have a working board only due to input from too many to mention. It is with some trepidation I take this next step.

[Waikiki_Sweep]

I have tried to upgrade Surf PI kit to PRO values. It works well. Only possible problem may be with overloading of integrator for bad coil or big target because for PRO gain in integrator is x2 higher. To be sure you can check output of integrator with multimeter. If you see 3.75V than it is overloaded. If less it is working. If you see the integrator overloaded make delay setting longer or coil with less internal capacitance or less power to impulses (R2) or bigger dumping resistor or less gain in opamp. First I have noticed about such overloads once I go deep in salt water and R2 was high so detector stops to react on targets. After adjustments all works good. May be you have a good coil and will have no such problem at all.

[multieagle]

Thanks Waikiki. Will keep an eye on it as I progress down the board.

[multieagle]

Surf PI Modifications March 19/14

TP1=0.00 was unable to adjust to zero using trim-pot, but using adjustable resistor at 3k3 adjusted to 0.00
TP2= -4.70 (negative)

NE5534
1: 3.32v
2: -1.83 (neg)
3: 0.011
4: -4.72 (neg)
5: 3.33
6. 4.99
7. 0.0
8: -0.659 (neg)

358
1: 0.591v
2: 0.011
3: 0.012
4: -4.72 (neg)
5: 4.99
6: 0.040
7: 0.013
8: 0.019

555
1: 0
2: 5.93
3: 11.25
4: 11.42
5: 11.43
6: 5.92
7: 5.93
8 7.59

7660
1: 1.42v
2: 2.51
3: 0
4: -2.35 (neg)
5: 4.99
6: 2.89
7: 1.43
8: 7.59

4093
1: 4.90v
2: 4.65
3: -4.44 (neg)
4: -4.44 (neg)
5: 4.97
6: 4.63
7: 4.72
8: 4.99
9: 3.44
10: 4.99
11: -3.66 (neg)
12: -4.70 (neg)
13: 4.99
14: 4.96

4066
1: .002v
2: .013
3: .002
4: .012
5: -4.44 (neg)
6: -4.72 (neg)
7: -4.72 (neg)
8: 4.99
9: -4.50 (neg)
10: -3.65 (neg)
11: -4.72 (neg)
12: -4.72 (neg

I have all pots, except the 3k3 variable resistor location, set at maximum. I do not have a coil attached. There is no

sound, which may be a wiring thingy to check. I'd like to ensure everything is working correctly before proceding. If

anyone notices errors in the above voltages would much appreciate a heads up.

TIA

Gord

[multieagle]

Just a quick update. I have sound, the added potentiometers appear to be working. What I have noticed is the voltage (neg/pos) has changed in a couple of areas from what has been posted elsewhere. Will post those values later today, along with a first coil test. Will attempt to take a couple of scope pictures of TP1 & TP2. For now, I need some rest.

[multieagle]

Okay, it works. Was unable to set the offset to zero with the variable resistor installed, so removed it and went back to the 3K3.

[multieagle]

Well, declarations of success were a bit premature. I had to remove the variable pot at 3K3. I am now not detecting anything, and there is no sound. Attached are scope images for TP1 & TP2. Was unable to obtain a square wave. There is no change in pulse, so would conclude I am not getting one. I'm open to suggestions if anyone cares to. I have doubled checked the soldering and can find no problems there. So it must resolve around the changes. Perhaps a component failure related to pulse generation, or one of the resistor replacements? I am able to zero the trimpot - the variable resistor ranges from 0.011 - 3.2.

C5: Replaced 470nF with 220
C6: Replaced 470nF with 220
c8: replaced 100nF with 47nF
R9: replaced 1M resistor with 1M pot
R16: replaced 220K with 470K
R17: replaced 220K with 470K
R20: replaced 22k with 47K
R22: replaced 100K with 220K

[multieagle]

I am not getting any response to metal with coil attached. Also, there is very little volume, just a steady very faint buzz (I have to put the piezo up to ear) which does not change when I work the volume pot. I can zero out the offset, but the value does not move when I wave metal over the coil. ( alternatively, when I adjust the variable resistor pot, it varies between 0.011 and 3.2v – so assume it is working). The offset pot does effect the delay setting, but the delay variable resistor pot by itself does not appear to do anything.

So, not to bother anyone too much, is there any way I can remove and test the ICs, or is it just a case of having spare test set on hand to replace/test? From what I can gather online, it is impossible to test all variables. Outside of lack of volume, my problem (I think) lack of pulse generation (IC?).

If you can view, or want to, board images posted here:
http://www.undergrounddetectors.ca/surfrevisions.JPG
http://www.undergrounddetectors.ca/surfrevisionsb.JPG

[porkluvr]

From frame #4, it looks to me like you are missing the +5V that should be on NE5534 pin-7 and LM358 pin-8. That's strange because you do show +5V on the CD4093. Look for a bad solder joint, or missing jumper... .

[multieagle]

I've checked for soldering problems and bridges. They all look okay. Just for sake of ensuring I've re-soldered a few iffy connections. I still have practically no volume and a constant barely audible hum. There is no apparent reaction when I pass a pair of pliers over the coil.

Here are the current values of NE5534 and LM358:

Variable Resistors at Minimum/Maximum

5534
Min:: /1:: 3.30 /2:: 0.006 /3:: 0.018 /4:: -4.66 /5:: 3.30 /6:: 4.98 /7:: 0.006 /8:: 0.634
Max:: /1:: 3.08 /2:: 0 /3:: 0.17 /4:: -4.65 /5:: 3.44 /6:: 4.98 /7:: -3.06 /8:: -3.65


Hmmmm, wonder if these are wired backwards?????


358
Min:: 1:: 0.532 /2:: 0.012 /3:: 0 /4:: -4.66 /5:: 4.98 /6:: 0.816 /7:: 0 /8::-0.062
Max: 1:: 0.947 /2:: 0.009 /3:: 0.012 /4: :-4.66 /5:: 4.98 /6:: 3.74 /7: : -0.469 /8:: -0.062

[multieagle]

Just an update. I have power across the board. There is sound on pins 5&6, 10&11 IC4093, all pots except sound volume appear responsive. There is voltage variance when I pass metal over the coil. However, I have no sound going to the speaker. Suspect it may be Q6, voltage (facing) Right leg: 4.59 Centre: 0 Left: 0

[pat4road]

Hi Multieagle and everyone. I am new to this very educational forum. I have just completed the Surf PI 1.2 from Silverdog. I was wondering is it normal with the volume cranked up all the way for the audio from the speaker to be so low. I own a Whites Surf PI Pro and the audio is much louder. Also are there post on this forum that someone can direct me to for any oscilloscope readings and test points for this kit.

[multieagle]

Seems to be a common problem. There are fixes suggested elsewhere. ( ie: http://www.geotech1.com/forums/showt...i-kit-no-sound or http://www.geotech1.com/forums/showt...+sound+surf+PI ) You will find the volume is good through a headset. Good luck!

[SVEN1]

I had the prtoblem on my orig build years ago. On geotech was the solution that worked for me.
Change out a resistor to a different value to suit your needs.

[pat4road]

Thank you multieagle and SVEN1. I wasn't sure what the volume was suppose to be. On some of the youtube videos the Surf PI unit sounds loud which led me to suspect I might have a problem. Thanks again. This is multieagles thread and I don't want to step on any toes. I just want to ask is it also normal to get a warbling or pulsating sound at threshold or should I hear a slight steady tone. If the solution is to lengthy please let me know if I should start a new thread.