On Saturday, 3 November 2018 11:38:28 UTC, John-Del wrote:
On Saturday, November 3, 2018 at 6:14:59 AM UTC-4, tabby wrote:
On Saturday, 3 November 2018 06:10:09 UTC, Phil Allison wrote:
tabby wrote:

Phil Allison wrote:
John Robertson wrote:



I know of no jukebox amp that had plug in capacitors. I agree that a
theatre amp is most likely - I too would enjoy seeing photos of these
amps you have!


** The idea of using high voltage, plug-in electros seems quite unsafe.

At the very least, the outside metal case would have to be well
insulated so a user would not receive a serious shock if a charged
cap was withdrawn from the socket.

Even then, some of the octal pins would be hot while others
would be connected to the metal case.

Sounds like some amp builder's ones clever idea that is a bit too clever.





it wouldn't have been any great concern back then though.
Expectations have much changed. Bare live bits are frowned on now.



** Tubes have long been user replaceable items, sold direct to the public. Biggest risk is the glass breaks or you plug it in out of key.

Building an electro with octal plug on the end makes it appear just like a tube, so just as safe. So it has to be.


.... Phil

now there's a non sequitur


NT


Well, I'm sure he's being sarcastic..

Still, a theater amp wouldn't generally be serviced by a novice as common radios and TVs were by consumers. A professional technician would hopefully be aware of the dangers of hot-swapping an electro just as he should be about using any line powered test equipment on a hot chassis without isolation. If it meant getting a theater amp running quickly I guess it made sense.


I've used 2 lots of cinema equipment from the 1930s. The small setup was reasonably safe, the full size one was another matter. Safety was not high on the list of concerns of whoever designed it, and it was top quality equipment (Kalee). If you opened the side of the thing and caught a glimpse of the carbon arc you wouldn't be seeing anything for a while. There was no latch, let alone a lock or interlock. Needless to say one needed to open the thing regularly to do the job.

There was also no easy way to check if the extractor fan was removing the arc combustion products, and of course no monitoring or interlock and no other vents etc. There were also zero precautions available for nitrate film. And lots of mercury in the rectifiers. The projection booth was all fireproofed though - but the fire extinguishing equipment totalled a single 1kg chemical extinguisher. A cap that might have killed someone that messed with it without knowing what they were doing would not have raised any concerns.


NT