- Replacing Electrolytics with NOS parts - 2 Updates
| whit3rd <whit3rd@gmail.com>: Sep 02 11:51PM -0700 On Friday, September 1, 2023 at 11:16:16 AM UTC-7, Peter W. wrote: > Now, here I am with a choice: $20 for a high-value, high voltage electrolytic cap. Or, $0 for a NOS one that, although never installed or used, has been sitting in my closet, or $8 for one that has been sitting on some dealer's shelf (properly conditioned, of course) for the last 20 years. I do all that has been suggested in this thread to bring that NOS cap up to proper behavior. Or so I think. > That cap goes *POOF*, and takes some unobtanium parts with it. > What have I saved? Why would an old stock capacitor fail? If it was battered, or stored next to the fuming nitric acid, or poor quality to begin with, maybe. But, if it's just normal aging of non-biased electrolyte, it's NOT gonna fail, just will take an initial hour or three under bias to reform the oxide. You've saved, in 98% of the probable cases, the time it takes to look up mechanically and electrically suitable replacements, and the overhead costs of shipping and receiving it. The unobtanium parts are fictitious, I won't address nonissues. If this were about a production run of 2000 units, with a deadline, and you couldn't take time to evaluate the whole batch, it'd be a different decision. |
| John Robertson <jrr@flippers.com>: Sep 03 08:25AM -0700 On 2023/09/02 11:51 p.m., whit3rd wrote: > The unobtanium parts are fictitious, I won't address nonissues. > If this were about a production run of 2000 units, with a deadline, and you couldn't take time > to evaluate the whole batch, it'd be a different decision. Electrolytic capacitors depend on the seal for their life. Seals aren't perfect and eventually the electrolyte dries out. Then the capacitor fails permanently, reforming isn't possible. Manufacturers recommend a shelf life of around ten years. These days, due to what I'm seeing in vintage equipment, capacitors from the 1980s and earlier simply can't be trusted. Caps from the 90s and 00's are suspects, but not yet time for blanket replacement. Except in monitors and switching power supplies...too warm an environment for the seals to last. John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
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