Neil - You'll get two sides (maybe more!) on this. The FACTS are ...
Electrolytic capacitors have a finite lifetime. Various sources give widely different _estimates_ of what this time 'is', and typically settle around 10 years in _typical_ environmental conditions, whatever those are. The cap has a paste that forms the dielectric, which contains water. Over time, this water evaporates resulting in a loss of insulating capabilities and/or capacity. Heat of course speeds up this evaporation, and depending upon how much stuff is piled on top of the radio, it can get pretty hot.
There are four main 'failure' conditions for an electrolytic. One is that the capacitance decreases considerably, another is that a 'series resistance' (presents as a resistor in series with the capacitor), another is it becomes 'open', usually as a result of a corroded internal lead, or, it just shorts out completely. All but the last one causes the power supply ripple to increase, (HUM,) and if the last one does happen, hopefully the power supply fuse will blow before the power transformer is destroyed! This last one is why the FIRST thing I do with a 'new' piece of vintage gear is check the fuse. I have found everything from the correct fuse, to a piece of #8 copper wire....
So obviously all of our Drake gear is on borrowed time if it has the original power supply caps. They may work for another ten years, or they may short out today. The choice is yours, 'do you feel lucky?', or are you a belt and suspenders kind of guy? If you feel lucky, just make sure the fuse is the RIGHT one. If B & S, check with Tom at hayseedhamfest.com. He has Twist-Lok caps that are a drop-in replacement and offers a complete kit that replaces ALL electrolytics in the various Drake radios.
73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs <www.k4oah.com> Neil M Califano wrote:
Should I recap my R-4A no matter what just because it is 30 years old?
_______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
