John Warren Posted September 17, 2022 Share Posted September 17, 2022 Recently acquired an early 80s Philips scope that appears to have very little use and immediately pressed it into service. Ran absolutely flawlessly for about 10 hours then... 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 BANG! Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 Power supply meltdown Quote Link to comment Share on other sites More sharing options...
Edgar Posted September 17, 2022 Share Posted September 17, 2022 Didn't anybody warn you about the self-destruct button? 🙂 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 The EMI filter cap (a RIFA) bursts. This is one across the mains, class X2 safety cap. Removed to show board distress. Note it did get hot enough to melt the shrink on the filter cap (2x50uF. 400V multi-section). Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 So, removed the 2x50uF, cleaned the mess and replaced the RIFA with a fresh X2 and a couple of new 50uF, 450V, low ESR Lelon's. Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 1 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 RIFA 0.22uF, 250VAC, CL-X2 Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 17, 2022 Author Share Posted September 17, 2022 Luckily the circuit survived the destruction of the safety cap, it opened. They're designed not to catch fire given the application across mains voltage (CL-X1 and X2). These capacitors have a reputation for failing. They're in all sorts of vintage test gear. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted September 19, 2022 Share Posted September 19, 2022 I just wanted to say I enjoy looking at what you are doing John. I hope to see more of your projects with pictures. We need more like this on this forum. You do excellent work. 1 Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 21, 2022 Author Share Posted September 21, 2022 On 9/19/2022 at 4:14 PM, henry4841 said: I just wanted to say I enjoy looking at what you are doing John. I hope to see more of your projects with pictures. We need more like this on this forum. You do excellent work. Thank you! Multiple projects including amp, test gear restorations, rebuilds and ground up new makes keep me happy. 2 Quote Link to comment Share on other sites More sharing options...
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