Re: Amp keeps blowing fuse
Posted: September 19th, 2019, 11:29 am
Agree about fuse, starting with a 3 amp slow-blow would be best.
If the DJH mod added a PS capacitor in series to improve reliability, retaining the original capacitor as part of the series stack (like the photo appears to show), then it is possible that the older capacitor was overstressed prior to the mod and finally failed. I bet the original cap was only a 350 to 400 V rated cap, and operating right at the top of its voltage rating. I also note that AE-25 is based on a 115V mains voltage, and I find that local voltage tends to be 120V (or even a little higher). This can result in a 4 to 5% higher B+ voltage than rated. This is all idle speculation on my part, but not unusual practice. It also explains why it was deemed necessary to add the extra cap.
David
If the DJH mod added a PS capacitor in series to improve reliability, retaining the original capacitor as part of the series stack (like the photo appears to show), then it is possible that the older capacitor was overstressed prior to the mod and finally failed. I bet the original cap was only a 350 to 400 V rated cap, and operating right at the top of its voltage rating. I also note that AE-25 is based on a 115V mains voltage, and I find that local voltage tends to be 120V (or even a little higher). This can result in a 4 to 5% higher B+ voltage than rated. This is all idle speculation on my part, but not unusual practice. It also explains why it was deemed necessary to add the extra cap.
David