Timeline for Why might a 40 year old single chip processor have failed?
Current License: CC BY-SA 4.0
30 events
| when toggle format | what | by | license | comment | |
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| Dec 24, 2021 at 8:38 | comment | added | emrys57 | Failure of the LCD is the normal way a Fluke 8050A dies. Changing the display to LEDs is the fix, documented in the link in th equestion. | |
| Dec 23, 2021 at 18:18 | comment | added | GT Electronics | Are you sure that is a Fluke 8050a? I had one and it has an LCD display without backlight. Yours appears to have LED 7-segment digits. | |
| Dec 23, 2021 at 16:46 | vote | accept | emrys57 | ||
| Dec 21, 2021 at 16:01 | comment | added | AnalogKid | Sam - oops. I did not know any of that. This forum's operations are significantly different from the others I'm on. | |
| Dec 21, 2021 at 15:31 | answer | added | Christian B. | timeline score: 2 | |
| Dec 21, 2021 at 15:00 | history | tweeted | twitter.com/StackElectronix/status/1473307299426930688 | ||
| Dec 21, 2021 at 14:35 | history | reopened |
Arsenal Null♦ HandyHowie Voltage Spike♦ |
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| Dec 21, 2021 at 13:33 | comment | added | SamGibson♦ | @AnalogKid - Hi, Re: "all questions are opinion-based. So are all moderator actions." True - but you seem to be implying that there has been a moderator action on this question. There hasn't yet! The question was closed by community voting, which is how the vast majority of closed questions get closed. Please see here. Also you said: "Please re-open" but you did not cast a reopen vote yet. Please see here and cast a vote, if you want it reopened. This is community voting in action - people can vote to reopen, as well as close. | |
| Dec 21, 2021 at 13:23 | comment | added | Arsenal | Seems like attention span is too short - the question is clear "What are the failure modes of an old IC and what are possible actions to reduce the risk?" even if the premise might be wrong (e.g. in this case it's some other fault). This question could be stripped down to only the last sentence - maybe putting it on top would reduce the risk of people mistaking this for a repair question or whatever. | |
| Dec 21, 2021 at 13:20 | review | Reopen votes | |||
| Dec 21, 2021 at 14:35 | |||||
| Dec 21, 2021 at 12:54 | comment | added | AnalogKid | AND - I don't think his focus on the uC makes this "opinion-based", just inexperienced. DUH - that is what this forum is for. (PS - all questions are opinion-based. So are all moderator actions.) Please re-open for a full discussion and answers. I grew up in the era of $20 "MIL-grade" hermetically-sealed IC's, and would love to hear about the failure modes that drove and justified their existence. | |
| Dec 21, 2021 at 12:52 | comment | added | AnalogKid | Since it ran worse the longer it was on, think thermal. Maybe pc board expansion stressing old solder joints. Also, "exercise" the switch(es) vigorously with or without tuner cleaner spray. | |
| Dec 21, 2021 at 11:18 | history | closed |
Andy aka Bimpelrekkie ocrdu TonyM Mitu Raj |
Opinion-based | |
| Dec 21, 2021 at 10:54 | comment | added | Kartman | Electromigration, ionic contamination, bond wire failure…. This list goes on. Without examining the chip it is anyone’s guess. Could you have done anything about it? Probably not. Besides, even with supposed abuse it lasted 40 years. | |
| Dec 21, 2021 at 10:03 | history | edited | emrys57 | CC BY-SA 4.0 |
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| Dec 21, 2021 at 10:00 | comment | added | emrys57 | Yes, nice, thanks MarkU. I did look at the electrolytics before I started, and couldn't see any physical change. And the power is still OK. I have an even older computer out in the stables somewhere... I'm not tempted to turn it on! | |
| Dec 21, 2021 at 9:56 | comment | added | MarkU | Somewhat relevant (from retrocomputing): retrocomputing.stackexchange.com/questions/5479/… | |
| Dec 21, 2021 at 9:46 | comment | added | Andy aka |
Is there any way I might have avoided it? - yes, you could have looked after it better and cared for it more and taken it on a walk once a day to read a volt or two.
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| Dec 21, 2021 at 9:45 | comment | added | schnedan | most chips have plastic housings, they are good in collection moisture, but might not transport it back to the outside fast enough (this is why good designed atomic bombs have e.g. ceramic chip housings...). Also ROMs have a data retention time... 40 years is certainly a possible time-span for ROM failures. In the Chip there might also be an aging of the points where the die is bonded... there are all sorts of possible failures. | |
| Dec 21, 2021 at 9:42 | review | Close votes | |||
| Dec 21, 2021 at 11:21 | |||||
| Dec 21, 2021 at 9:38 | comment | added | emrys57 | When the processor first misbehaved, I checked the oscillator with the scope: a nice 4 MHz signal, no problem. So the crystal was not failing at that time, yet the processor was producing the wrong output. I conclude that the fault does not lie with the crystal. I'm not asking what's wrong with my DMM. I'm asking, what might cause an old plastic chip to fail, and could I have avoided it? | |
| Dec 21, 2021 at 9:31 | comment | added | Bimpelrekkie | We all know that cold and damp isn't good for electronics. I would just leave the PCB in a warm and dry place for a week and then try again. We can only guess about any failure modes as you haven't proven anything yet. If you would replace the MK3870 and that would fix the issue, only then would you have proven that it was the MK3870. | |
| Dec 21, 2021 at 9:28 | comment | added | Spehro Pefhany | How do you know the crystal hasn't failed or got excess leakage on the PCB? Or that your scope probe is not loading the oscillator? | |
| Dec 21, 2021 at 9:26 | history | edited | emrys57 | CC BY-SA 4.0 |
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| Dec 21, 2021 at 9:26 | comment | added | emrys57 | Yes, I checked with scope. Yes, I looked at the reset pin. | |
| Dec 21, 2021 at 9:25 | comment | added | Justme | How do you know power supply is working correctly? Have you verified it with oscilloscope that it has no excess ripple? The CPU depends also on other external components. What if the capacitor on reset pin failed? It is not very difficult to imagine that a single point of circuitry being out of spec causes processor to not run. | |
| Dec 21, 2021 at 9:22 | comment | added | emrys57 | There is just one power supply to the single chip micro and it is working correctly. It's difficult to imagine how the chip can get power, have the oscillator not run, and not have failed. | |
| Dec 21, 2021 at 9:21 | comment | added | Justme | What makes you think the CPU failed? What if the problem is somewhere else, like failed power supply? Or dead capacitor somewhere? | |
| Dec 21, 2021 at 9:18 | comment | added | Arsenal | "A tragic tale, but at least the old DMM got to measure one last voltage before it died." +1 | |
| Dec 21, 2021 at 9:13 | history | asked | emrys57 | CC BY-SA 4.0 |