Search results for query: logic probe

...the streams of data from one chip against another good chip in real-time. You sometimes can narrow down problems like this with a logic probe, but it takes experience. And the ability to listen to and compare what you can hear with the probe, against another known-working board, side by...

Here are a bunch of related threads you can spend time with. I just searched for threads that have posts by me containing 'logic probe' in them. Some may be more applicable than others. But that should give you examples of how people go about starting to troubleshoot dead boards. There are...

This is what I do. The Elenco LP-560 has this feature. If it resets even once, something isn’t right.

You should order a logic probe if you don’t have one, and do some poking around fist, before shotgunning a bunch of chips. You’re more likely to cause new problems just replacing stuff, which makes finding the original problem even harder. The Elenco LP-560 is a good cheap one most of us...

Got a logic probe? If not, time to get one. It won’t fix everything, but it’ll let you get more insight into what’s going on, on the board. It’s the next tool up from a DMM. Elenco LP-560. $25 on Amazon.

Do you have a logic probe? If not, get one. Today. Elenco LP-560. It should be $20-25. That will let you test the enable signals for each sound, and see if the one in question is stuck. You want to troubleshoot here, and hone in on the root cause. Guessing at replacing chips is...

Have you done signature analysis on a main board first? If not, you might want to try that first, just to verify the rest of your setup. IMO, doing an aux board is a step beyond that. I've never needed to do more than what I described above. Forcing RESET low doesn't make any sense...

...There's only going to be so much you can do at this point, without the right tools. Your best bet is to send it out. Or get a logic probe and start tracing logic and see if you can get lucky. Also, the importance of visual inspection cannot be overstated. Hold the board up to a light...

...for deeper problems. Otherwise you'll waste a lot of time, and replace a lot of parts that don't need to be replaced. Also, you want a logic probe. Get an Elenco LP-560 ($25 on Amazon or ebay). A probe is the simplest low-level tool that gives you insight into what's going on with a...

...don't have to give the board 10.3V, and can power everything with just +5.) That gets the CPU and VG working. Then you can take a logic probe and observe the 10 data lines of the DAC inputs. If you look at what they look and sound like on a working board, that will calibrate you to...

...that, than fixing existing ones. Guessing is not a troubleshooting strategy. Get the tools you need to troubleshoot correctly. A logic probe, a cap meter, and ESR meter and a DMM are a good start. (And learn how to use them.) You want to MEASURE things, FIND problems, and only when...

...to see if the sound board has a clock. The schematics are here: https://www.arcade-museum.com/manuals-videogames/G/Gyruss__1983__Konami.pdf PDF page 32 has the sound board schematics. The clock section is in the upper right. You'll need a logic probe to see what's going on there...

Most likely a board issue. The green output might just be dead, which would require tracing it back to see if/where it's bad. You would need at least a logic probe to debug.

Buy a $25 logic probe, and troubleshoot this properly, where you test the joystick signal to see if it's making it to the game board. That will tell you if it's the game board or wiring. If it's a wiring issue, you use your DMM to figure out where the break or bad connection is. If you...

...to point, using the schematics, to see if you can catch any bad connections. But this can be tricky with busses. You could also use a logic probe to try to find bad signals on the CPU side, but again this is a crapshoot. Sometimes you can find problems with a $25 logic probe (or by...

...to tell. But sometimes they can get stuck. (You can spray some DeOxit into it to loosen and lube it up, if needed.) If you have a logic probe, you can also use that to test the button. (Or a DMM.) If it isn't the button, then something else is holding RESET low, which you'd want to...

The logic probe will let you look at pin 40 of the CPU, which is the reset line. If it is toggling up and down, that means the board is watchdogging, meaning the CPU isn't running properly, and the watchdog circuit is continually resetting the CPU. It'll also let you check the clocks to make...

...CPU and ROMs can get a game working again. Then try redoing the self-tests above. Beyond that, you're going to need more tools. A logic probe at least. If you want to get one, google Elenco LP-560. It's a cheap one that many people have here, that works well. They're about $25. It...

I usually just use a logic probe to start. And I'll piggyback chips that I suspect might be bad. I rarely use a scope. Did we determine the board isn't watchdogging? Is it playing blind? You can lift pin 11 of the LS139 at K5 (VGGO) to disable the VG. If you do that, and it plays...

...even breaking out logic analyzers or other complex tools. So you start with the simple physical things (visual inspection, self-test, logic probe, etc). And save the more complicated things for last, if the easy ones don't pan out. I have an HP comparator. But rather than use that a lot...