Electronics > Beginners

Troubleshooting Microprocessors

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ogden:

--- Quote from: bostonman on January 02, 2020, 07:08:40 pm ---I've kind of run out of ideas and feel maybe I should readdress repairing this in the future as I feel my measurements take me in a loop.

--- End quote ---
Yes. Sorry to say, but seems you need to learn basics first until you actually understand what you are doing. Looking at "full screen of signals that jump around" do not sound like CPU troubleshooting at all. What you *can* do in this case - find someone with hands-on C64 knowledge to guide your troubleshooting steps according to your (rather limited) level of expertise.

bostonman:

--- Quote ---Yes. Sorry to say, but seems you need to learn basics first until you actually understand what you are doing.
--- End quote ---

Just to clarify, I'm an engineer, just lack microprocessor experience. Any experience was all theory and any hands on was at a minimal.

Upon posting my question, I never thought I'd receive the extensive feedback focusing on the C64 that I did, so I appreciate it. Obviously I learned a bit more than I knew about uprocessors, but still need much more knowledge (and why I posted my question in 'Beginner'.

Many basic questions still exist like how would I sync my oscilloscope to the microprocessor? I'd need to tap off the clock circuit, but not sure if it can drive the scope. So maybe I'd need to build a buffer amp. I have a 64-channel logic analyzer (two actually) that I'm uncertain work; maybe I'll try connecting one of them.

ogden:

--- Quote from: bostonman on January 03, 2020, 07:37:08 pm ---Many basic questions still exist like how would I sync my oscilloscope to the microprocessor?

--- End quote ---
https://www.testandmeasurementtips.com/the-trigger-function-of-an-oscilloscope/


--- Quote ---I'd need to tap off the clock circuit, but not sure if it can drive the scope.

--- End quote ---
Clock of CPU is logic level signal as well. Don't measure clock at the crystal terminals. measure at the clock buffer output.


--- Quote ---So maybe I'd need to build a buffer amp.

--- End quote ---
No. Clock is logic level signal, any scope can show it w/o any buffers. Schematics of the thing will be very, very helpful. Do you have it?


--- Quote ---I have a 64-channel logic analyzer (two actually) that I'm uncertain work

--- End quote ---
Leave it alone at the moment, 2-channel scope is good enough for basic troubleshooting. When you see that you need more than 2 channels - THEN look for logic analyzer.
[edit] Logic analyzers show only 0 or 1, they do not indicate logic signal integrity which is much more important in your case. So stick with scope.

bostonman:

--- Quote ---No. Clock is logic level signal, any scope can show it w/o any buffers. Schematics of the thing will be very, very helpful. Do you have it?
--- End quote ---

I meant is the clock signal (I know not to take it at the crystal - and I have schematics) capable of driving the impedance of the scope along with the C64 circuit?

ogden:

--- Quote from: bostonman on January 03, 2020, 08:11:26 pm ---
--- Quote ---No. Clock is logic level signal, any scope can show it w/o any buffers. Schematics of the thing will be very, very helpful. Do you have it?
--- End quote ---

I meant is the clock signal (I know not to take it at the crystal - and I have schematics) capable of driving the impedance of the scope along with the C64 circuit?

--- End quote ---
Yes indeed. Clock buffer is one of strongest digital signal source in such devices, it will not even notice 10MOhm scope probe connected. Could you please share URL/link to schematics, if any.

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