I don't know why, but the DC buss capacitors are very sturdy components. And they usually do not fail as their smaller capacitors often do. I will replace them when they show signs of failure. When they bulge or burst open. That is a very good question. Thank you:)

@@PeepawMcDonald The smaller capacitors (in voltage, and value) tend to fail more, because they use more 'advanced' electrolytic solution to get the most capacitance in the least amount of board realestate. For large capacitors (DC bus caps in VFDs and even the main DC bus caps in switching power supplies), there tends to only be one of them, and it's more important that it doesn't explode at 400VDC than how much board area it takes up, so they tend to use less advanced, but more stable electrolytic solutions in them, but with lower dielectric constants, so the capacitors need to be bigger. That's why there's different "series" of capacitors from every brand aimed at different applications. The ones that tend to fail most are the ~1000uF to 4700uF, and 16-50V, as that's usually where they're trying to save board space. Back when the "capacitor plauge" was in it's heyday in the late 90's / 00's, when replacing failed capacitors on motherboards with less than stellar brand capacitors, it was impossible to find replacements from reliable brands that had the same footprint. The equivalent caps from Nichicon/Chemicon/Rubycon/Panasonic were 30-60% larger in diameter, and they just didn't have anything in the shrunken sizes. Once replaced, the larger capacitors were always way more reliable and never needed to be replaced again. Caps below 1000uF tend to be small enough anyway to not worry about using the advanced electrolyte, so they tend to be ok - but they can still fail, just not nearly as frequently. I suspect the cap that failed here was a "random" failure - could be the seal failed and it dried out. Some of those first miniaturized surface mount electrolytics were horrible, and known to fail - there's a particularly failure prone series of those that were used in certain generations of Tektronix scopes. It's not if they fail, it's when, and how much electrolyte do they spill on the board and eat the traces away. Even the good brands have bad series too - certain series of chemicon and nippon caps, used extensively in Mitsubishi drives and CNC controls, are pretty much guaranteed to fail and leak, and destroy traces.

@@gorak9000 Thank you for you knowledge. I often wondered why the larger buss capacitors rarely failed as compared to the smaller capacitors. Can you explain why capacitors of the 60's, 70's, 80's are still going to this day? Thank you:)

@@gorak9000 thank you for your information So in your opinion budged valve of caps is a certain sign of damage ??

Just wandering mind for a little bit. But I believe there is a repair shop on the very outskirts of our solar system. That the space craft went out researching with suspect bad components. And just as they were on the verge to failure. The galaxial repair shop refurbished their circuit boards. So that they could continue on with their journey. Either that or things were made to higher quality spec in the olden days:) For some reason, I like the first explanation much much better haha...

@@PeepawMcDonald “She Canny take anymore Captain”

Yes, I programmed the PIC16F877 micro controller. It is made by Microchip

@@PeepawMcDonald Cool !!! I’m a sparkie but I dabble in electronics and Pic. micro,s . Have done a few projects using the Pic16877.

I am so sorry, but it is very difficult for me to take on new repairs. I had a brain stroke back in December of 2023 New Years. I was paralyzed on my left arm and left leg. When I was in the hospital they diagnosed me with type2 diabetes. The diabetes most likely caused the brain stroke. Just about the time I get to enjoying life. The machine that I live in wants to quit being faithful. Three months of therapy got me using my left side again. But here recently my left arm and hand appear to be failing me again. They feel weak and do not want to fully obey commands from my brain. My left eye vision has gone south also. I have black spots and wisps of spider webs that invade my view. Back in 2021 my son killed himself. That really broke my will to continue. If it were not for my Daughter and Grandchildren. I am a tough old man from a different age. But I am so tired. I am so sorry. Thank you for listening to an old man's rant. We will be okay. And if we will not be okay, at the least we will get used to it.

@@PeepawMcDonald Im so sorry I send you a hug from Costa Rica, your videos are awesome, maybe you can open a subcription and teach this "gadgets" and sell it regards

@@ignaciomonge5385 Thank you:)

Thank you.

Very good question. I made a video today looking at the input waveforms of the opto coupler. And the output waveforms of the opto couple. kzfaq.info/get/bejne/sOBleJylyMC1gZ8.html I hope this answers your questions about the circuit.

Thank you for you kind words. They mean a lot to me.

Thank you so very much. I need all the encouragement I can get Haha. How is your shop going. I hope all is well.

Thank you Matt. How have you been. Me and Tommy the cat are doing the best we can :)

Thank you so very much.

How have things been going with you and your family. It is good to hear from you again. We are limping along here. HaHa... But other than the hitch on my left side we are doing well :) Thank you for watching.

@@PeepawMcDonald All ok thanks. Weather is sunny and warm here in the UK. The warm weather helps with the arthritis and the long days are always welcome in summer. Sending you blessings and positive vibes across the pond God bless you all.