Quote:
Originally Posted by bandersen
Beautiful job but one thought occurs to me. Capacitors can get warm from self heating due to internal ESR plus ripple current. Especially the main B+ filter caps. Sealing them up with hot glue and PVC isn't going to allow them to breathe much and may hasten their demise.
|
Quote:
Originally Posted by Crist Rigott
Thanks Bob. Good thought. After I get it running and with the can off I'll do a temp measurement and report back. I just might need to be reminded. Then again with the can on might be a good idea. We'll see together how this method works out.
|
I checked the temps today using my HF infrared thermometer. I took a measurement when I started, then 2 hours later. Here are the results:
E-Cap - Start - 2 Hours later with Can - 2 Hours later without the can
C1 - 22C - 46.1C - 39.3C
C2 - 22C - 63.1C - 43.9C
C3 - 23C - 45.7C - 40.4C
C4 - 22C - 38.0C - 32.9C
C2 is located on the power supply chassis next to V11 6BF5 audio output tube. This tube glows brightly under normal operation and gets very hot. IIRC it measured @268 F.
It looks like the can and sleeve actually acts as a barrier to the surrounding heat of the chassis as shown by about a 3 to 5 degree difference between the can being on or off. The exception is C2 due to being close to the 6BF5.
This test wasn't very scientific but does demonstrate that enclosing them in the PVC and their cans actually proves to reduce the heat of the E-Caps. In any case, all of these E-Caps are 105C and are no where near their rated temperature.
I did a life span estimate from the Nichicon website of C2 22uf 500V E-Caps at 45C, and their life span was 131,400 hours. That's about 45 years at 8 hours a day, every day!