dyno
Well-known member
What is the best way to test an IC?
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What is the best way to test an IC?
Fixed that for ya.Oscilloscope and Logic Probe.
Fixed that for ya.
Testing really depends on the type of part. But generally, what Arcadenut said. You'll also want the datasheet for the part in question. First, measure the power supply using a multimeter or a 'scope. Once that checks out, then measure the inputs/outputs with the logic probe or 'scope and compare with the expected values from the datasheet. The oscilloscope will give you more detailed information, but the meter and probe are much easier to purchase (=cheaper) and are typically enough for just logic chips. If you want to check analog chips, you'll need the 'scope.
Personally I use one of these
BK575A for Logic
Or BK570 for Linear
But not everyone has one, plus it require chip removal.
In circuit like the others have stated.
Well there's not an easy way to go about it. I think most people use a logic probe to look for stuck bits. IE bits that are supposed to toggle but don't.
In most cases you will need to look up the data sheet, and wire in +5 and gnd, then put a 1 or 0 one the inputs of the suspect chip. Compare the output with what the truth table states in the data sheet.
Well my problem is that I can measure voltages at all the test points on various roms, rams, processors, component leads, etc. and notice some voltages are incorrect and others are in range, while still others are low until that chip is accessed then higher. I thought buying a logic probe would help, but these data sheets have so many possible if, then, scenarios I can't figure out whether the ic is bad or it is reading bad because of some other bad input. It would be nice to see a tutorial that says, 1.go into sound test, 2.select machine gun sound test, 3. Test voltage or logic at pin xx for this or that. 4. If it reads this then test that. If it reads something else than test some other xxx. Are there no game specific tutorials out there? Because I haven't found any for spyhunter. If I thought one of these $1000+ ic testers could actually verify a chip good or bad in circuit I would buy it in a heartbeat. But I am not going to unseat or desolder every chip on a cpu in order to test it. Help
Well my problem is that I can measure voltages at all the test points on various roms, rams, processors, component leads, etc. and notice some voltages are incorrect and others are in range, while still others are low until that chip is accessed then higher. I thought buying a logic probe would help, but these data sheets have so many possible if, then, scenarios I can't figure out whether the ic is bad or it is reading bad because of some other bad input. It would be nice to see a tutorial that says, 1.go into sound test, 2.select machine gun sound test, 3. Test voltage or logic at pin xx for this or that. 4. If it reads this then test that. If it reads something else than test some other xxx. Are there no game specific tutorials out there? Because I haven't found any for spyhunter. If I thought one of these $1000+ ic testers could actually verify a chip good or bad in circuit I would buy it in a heartbeat. But I am not going to unseat or desolder every chip on a cpu in order to test it. Help
I don't think you're ever going to find a troubleshooting flowchart like that because there are so many paths, it would be 10,000 pages long. What you need to have is an understanding of how IC's work and why, and how they work together. Then you need a test bench with at the very least power supplies, a DMM, logic analyzer, and maybe an oscilloscope,.. and understand how, when, and why to use each. Then you could do the troubleshooting and detective work to find the one or more bad chips on the boardset and fix them.
... or you could find someone who has all of this already, who fixes those boards, and send it to them.
Well, every game is going to be different. Your best bet is to identify the problem, then break out the schematics and go from there.
Let's say you have no Audio on Spy Hunter.
Basically you're doing a process of elimination starting at the end and working your way backwards until you find the source of your problem.
You go to the schematics and find where the speakers are and you start testing there. If nothing is getting to the speakers, then you work your way back through the schematics. If something is going to the speakers you could have a bad ground or a bad speaker.
If not, start working your way back. In this case the IC at D3. Looking at the schematics pins 4 and 5 feed the speakers. If you're not getting anything form there, then you check the input side of things (pins 1 and 2). If you get something there, then you probably have a problem with one of the components connected to pin 3 or 6.
This is obviously for simple example and there could be a lot nastier issues, but it should help you at least eliminate a bunch of things.