Help With Delta Pulse Problem

		Quote:			Posted by japanese
	Thank you  GD  --- and I'll leave the response from all members of the ruling -------- it seems -----I will stop myself from responding so apologize-------

I don't mean for you to stop, mate. Just stop telling people to modify a machine that doesn't work in an attempt to make it work. Verify substitutions when you suggest them. Twice now I have found frequency response errors in your recommended Op Amp replacements that would have made things worse, not better. I thank you for your contributions. Just be more careful with your advice.

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		Quote:			Posted by viswanathmarachi
	Firstly thank you both for helping me trouble shoot my circuit.  Secondly I am so sorry for becoming a platform for this situation.

The only opposition to advice given so far is that any recommendation to change a design is going to cause you trouble compounded. Until you get the design working as it should, modifying it will not help at all and the advice being given was to substitute parts rather than find the actual problem.

Now that you have checked and verified your project as far as the parts are concerned, it's time to break out the multimeter and do some tracing of the copper on your board. There is a possibility that two traces are shorted together by a hair sized amount of copper on one hand. On the other, there's a chance that a hairlike fracture in the traces could present an open circuit. The only way to check this is with a magnifying glass (or loupe if you have one) and a multimeter to check resistance and continuity. Verify all component connections to the board. In other words, look at the schematic and be sure that each black line connecting the components goes to all of the places that they should. Inspect VERY carefully and slowly. A tiny crack or short may be very hard to spot. Also, while you are at it, look for cold solder joints. A solder joint that is properly made has a volcano like shape. A ball of solder setting on a lead is a cold solder joint. One that looks like a shiny hill is proper.

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Often, DIY projects cost more in time and effort than just buying one. The failure rate on completion by a non technician is very high. At the end of the day, a second hand Tesoro Compadre is only around $100.00 plus shipping. You can recover twice that in a day in areas like yours where metal detectors are rare and the population is large.

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Make sure you verify the traces and tracks of copper against the schematic. Also, pop all of your ICs out and look at the legs. Check them for bent or broken legs. Do your resistance measurements against the schematic while the ICs are out of the circuit. Some are CMOS which could be damaged by the multimeter. In fact, as has been mentioned, those parts are already suspect simply because they are CMOS parts. CMOS chips (ICs) are sensitive to static electricity, stray voltages or reverse polarities. That diode might have killed one or more of them when it was backwards. Before you put them back in again, we will need to start a bit more troubleshooting. Have a little patience and we'll get you up and running. It's quite hard to do this when you are 8,000 miles away but we'll give it our best shot. We're done with the guessing games. It's down to hard facts now.

Would you attach the schematic here for the project as you built it? As you know, there is more than one version out there. I want to study the one you chose. Also, when you can do so, grab a small speaker from an old computer, radio, stereo or TV set which will help us in troubleshooting. Solder some soft wires to the speaker. Make the wires about 18 inches long and tin the ends of the wire. We'll be using that to verify a few things as we bring your board up section by section.

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		Quote:			Posted by 6666
	Interesting, I am following another thread were the fellow had all the BC546 Transistors reversed as well.

A common mistake with the device. There are even some differences between manufacturers of the same part. Crazy.

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