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Post by terryrocks on Aug 3, 2015 20:33:55 GMT -6
i bought someone else's 1176 project and want to probe it a bit.
i have a signal generator and a dual trace oscilloscope.
if i want to use the signal generator to feed signal to the circuit i use a bnc cable with two leads, a ground and a hot(i think). Which goes where on my 1176 input? i assume ground to ground.
My plan is to use the dual trace feature to compare virgin signal to that which I'm sending through the 1176.
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Post by jeromemason on Aug 3, 2015 23:00:59 GMT -6
Is it a clone or an original??
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Post by svart on Aug 4, 2015 7:21:11 GMT -6
Pretty sure he means a clone.
I gotta be honest though, if you don't know how to hook up a signal generator.. Are you sure you're ready to tackle a debugging job? Debugging a faulty unit is a lot harder than just building one..
So what's the problem it's having? I'd just inject a known signal(sine, 1khz) and probe through the circuit looking for where it cuts out or gets distorted first. That's usually quicker than trying to figure out specifics before you understand the problems.
Also, you need to check the power supplies first and foremost, then track down each power rail to the parts. There are already a lot of schematics online where folks have annotated the voltages for you.
When that is done, triple check all wire connections. That's probably the most common error in these kits.
If both of those look OK, I'd check the solder joints. Most of these kits have been pretty good about keeping the parts spaced out enough for most people to avoid solder bridges, but check anyway. When in doubt, reflow all the solder joints.
Lastly, that's when I'd start tracing through the circuit with a signal. Chances are someone just stuffed a wrong resistor somewhere. It might be worth it to pull a leg up on each resistor and check it's value with a DMM. It would take a few hours, but it could save you a lot more hours of troubleshooting.
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Post by terryrocks on Aug 4, 2015 10:02:00 GMT -6
Thanks, but the question was about how to inject the signal. That's the first thing I need to know before I can either hook up the o scope or signal trace. I just don't want to hook it up incorrectly for fear of damaging something.
It's a clone using mnats rev h board,
The guy I bought it from said it passes signl fine but that the gain reduction ciruit isn't working.
My plan, again, is to begin by checking a known waveform against one passing through the unit.
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Post by svart on Aug 4, 2015 11:52:14 GMT -6
To answer your question, if your signal generator is single-ended, then you'll need to ground pin 1 and either pin 2 or 3 and then inject your signal into the one not grounded on your input XLR.
I still don't understand though.. How can you say you're going to troubleshoot this effectively but don't know how to hook up a signal generator, nor know if it'll "damage" something.. Hooking these types of things up is one of the fundamentals of electronics.
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