Quote:
Originally Posted by zeno
Nice work. A crude test on the caps is grab them by
the leads with needle noses & pull. They usually
come apart. Triplers cracked open left & right on
most sets back then. RCA seemed to have the least problem.
I remember now 977-36 was the latest # for this tripler.
Used to get them by the dozen from Zenith for $10
each, almost as good a profit as tubes.......
73 Zeno  |
The polymide epoxy used as end seals on the white caps (Elmenco and ASI were two brands) shrinks over time, pulling away from the ceramic case. The impregnant leaks, and you have a bad cap. I've got NOS ceramic caps that went bad on the shelf - it was the epoxy end seals that failed, with no stress from being installed in anything. Heat accelerates the shrinkage, which is why the big .1/1000 in GE porta-pottys typically fails - it sits right next to a nice hot compactron.
The triplers were made either by VARO or EDI. EDI ones held up pretty good - they typically used a polypropylene shell that "gave" a bit when warm. This helped prevent cracking. VARO (light gray, or the ubiquitous Sylvania white) typically failed with cracking or arcing. VARO fixed their problems and outlasted EDI in making triplers. The replacement ones (ECG/SK/GE) were hit and miss, as you could have two same-marking ECG523s, one an early VARO and one a later one. They cleared up things somewhat in adding the "a" suffix to the ECG number. Occasionally the non-"a" triplers appear on eBay - avoid them unless there is a date code of 1980 or later, hard to tell in most photos.
The orange drops have differences too - the pulse rated ones (715P and 716P) are made of polypropylene (PP or even MPP) dielectric, and should be the ones used. The polyester ones (225P and 418P, and "PS" series) were for non-pulse coupling and bypass use, and should not be used in pulse applications such as safety caps. The higher voltage 225P and PS series caps were for buffer caps replacement in old car radios using a vibrator supply.
Cheers,