Best way to test an intergrated circuit

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.
 
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.

If you're going to buy/rent/borrow an oscilloscope, then you might as well buy/rent/borrow a logic analyzer too.

I was going to say, 'send it out'. :p
 
Personally I use one of these

BK575A for Logic
BK575A.jpg


Or BK570 for Linear

BK570.jpg


But not everyone has one, plus it require chip removal.

In circuit like the others have stated.
 
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.

Those are pretty nifty. How extensive is the built-in library of ICs? Do you ever run into parts that aren't in its database?
 
Yeah, they're great and really cheap at over a grand each. Can you recommend something under $200 for use on classic games? And where can I find a tutorial on how exactly to use my logic probe to test my spyhunter sound board? And what each chip should read?
 
I have something similar I found in a box called a "Data Genie", but I haven't looked into how to use it and what it can be used to test yet...
 
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 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

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.
 
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.
 
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.

This.

Problem is, you're asking for "exact" instructions on how to use one inaccurate tool to fix a vague problem. Can't be done.

If you're not willing to spend some time learning up on the theories, math, and practical applications of electronics, then you're not going to get very far. Might get lucky once in a while.
 
I kinda like Randy Fromm's tip:

Set your DVM to diode test
Hook up the PLUS lead (red) to GROUND
Touch ALL the pins of all (suspect) chips with the minus lead (black).
If it beeps, you have a problem (unless it's supposed to be GROUND of course).

I only tried it once and I indeed found a bad chip this way.

I know it's not scientific and I know it surely won't find all problems, but it's worth a try and it's QUICK.
 
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.

Thanks for the detailed responses. I had already traced one problem back to D3 and also restored the missing grounds in the game. I guess I'm frustrated because there seems to be multiple failures in my game and since I can't find D3 locally, I didn't want to mailorder just for that part until confirming other possible problems, like the ram chip I also suspect. I would like to order everything all at once but that might be wishful thinking. I can follow schematics but I'm no expert at knowing how each component affects the others and can't always follow the flow of the circuitry in complex systems. I need to be more patient most of all.
 
Back
Top Bottom