kynikos Posted May 13, 2022 Share Posted May 13, 2022 Hi all, I recently picked up my first C64 and am a bit confused after running some diagnostic tests. On both the 586220 and 586220* diagnostics my 6518 U18 is showing as "bad", which I understand is the SID chip. However, when running the SID Tester by Andrew Challis, everything passes and I can hear all the sounds fine. Games sound fine as well. Should I be concerned that my SID dying or would this just be a diagnostic test discrepancy? Thanks in advance! Quote Link to comment Share on other sites More sharing options...
bjonte Posted May 13, 2022 Share Posted May 13, 2022 The question is what the test is really testing. Since the machine can’t hear the SID it can only look at the input it has - paddles and the waveform/envelope output registers. So either paddles aren’t working or reading the waveform output isn’t working properly. Try paddles on it or a program that auto detects the SID type. Either of those might be failing. Quote Link to comment Share on other sites More sharing options...
hofster Posted May 13, 2022 Share Posted May 13, 2022 Hi all, I recently picked up my first C64 and am a bit confused after running some diagnostic tests. On both the 586220 and 586220* diagnostics my 6518 U18 is showing as "bad", which I understand is the SID chip. However, when running the SID Tester by Andrew Challis, everything passes and I can hear all the sounds fine. Games sound fine as well. Should I be concerned that my SID dying or would this just be a diagnostic test discrepancy? Thanks in advance!The SID is used for reading analog joysticks and the 586220 is testing that functionality as part of the control port test. It reports bad SID if the analog parts of the control port tests fail.You need a test harness that connects to the control ports and other ports to run the 586220 and get all good results.Is the bad U18 indication showing up right after the control port test has finished? Quote Link to comment Share on other sites More sharing options...
kynikos Posted May 13, 2022 Author Share Posted May 13, 2022 54 minutes ago, hofster said: The SID is used for reading analog joysticks and the 586220 is testing that functionality as part of the control port test. It reports bad SID if the analog parts of the control port tests fail. You need a test harness that connects to the control ports and other ports to run the 586220 and get all good results. Is the bad U18 indication showing up right after the control port test has finished? It basically looked like the attached image. I had nothing else plugged in so that might explain it. I'm not sure I want to spend the money on a test harness right now as this is my only C64 and I don't really plan on getting more. Quote Link to comment Share on other sites More sharing options...
hofster Posted May 13, 2022 Share Posted May 13, 2022 If it sounds good and you don't have paddle problems you don't need to care about it Quote Link to comment Share on other sites More sharing options...
hofster Posted May 13, 2022 Share Posted May 13, 2022 Deleted Quote Link to comment Share on other sites More sharing options...
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