unclej Posted February 1, 2005 Report Posted February 1, 2005 i've got another ampeg in the shop and want to know about a particular cap. there's nothing wrong with it i'm just curious. it's a .047 mfd, 1000v black cat and it runs from the standby/polarity switch to the board where it goes to ground. what's it's purpose and why the high voltage? Quote
lovekraft Posted February 1, 2005 Report Posted February 1, 2005 I would assume it's there to shunt any switching transients to ground - don't know what the voltage levels are in that amp, but transients from an inductor/transformer can reach very high voltages, well above twice the AC voltage. Quote
JohnnyG Posted February 1, 2005 Report Posted February 1, 2005 is this think on a 2 prong plug? just that ive seen quite a few old amp schematics that have a cap that can be switched between ground and one of the mains lines before the power tranny. i dont know if thats it but other than what LK said its all i can think of. Quote
lovekraft Posted February 1, 2005 Report Posted February 1, 2005 Yes, only amps with 2 prong plugs have a polarity switch - that's why there might be switching transients, since it would swap ground from one mains lead to the other. Unk, don't want to sound like a nag, but you know that you really need to upgrade that to a grounded plug so your customer doesn't eventually fry himself, right? Quote
truerussian558 Posted February 2, 2005 Report Posted February 2, 2005 i found out an interesting little tidbit. Ground switches have been illegal (to manufacture and sell new devices with them) for 7 years, so your best bet is what lovekraft said to install a 3 prong cord, and drive the green wire (usually it is green) to the chasis ground point. and deactivate the ground switch Quote
unclej Posted February 2, 2005 Author Report Posted February 2, 2005 lk, you can nag all you want as long as i keep learning. but you already nagged at me about replacing those cords and that's the first thing i do now. actually that's how the question came up. the black cat comes off of a standby/polarity combination switch and after i put the new cord on i was wondering if it was still necessary and what it did. i left it alone by the way. but i'm curious..what do cross dressing homeless people have to do with amps? (switching transients ) oh quit it...you know you thought it was funny. as always, thanks to all for the input. Quote
JohnnyG Posted February 2, 2005 Report Posted February 2, 2005 but i'm curious..what do cross dressing homeless people have to do with amps? (switching transients ) oh quit it...you know you thought it was funny Must not laugh...must not giggle like a little girl....LOL damn you Quote
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