Ampeg mistake
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Stevem
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Ampeg mistake
I forgot to post that this vt40 I was working on had a blown up original death cap, this think left the factory with a cap rated for 120vac!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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gingertube
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- Location: Adelaide, South Oz
Re: Ampeg mistake
Then it wasn't a Class Y safety rated cap and was illegal.
Must have been before Class X (Active to Neutral) and Class Y (active or neutral to ground) was ïnvented".
Lucky the only death was the cap itself.
Safety Tip for old amps - if you are not going to get rid of the death cap entirely then seriously consider replacing it with a Class Y Safety rated cap of the same value.
Cheers,
Ian
Must have been before Class X (Active to Neutral) and Class Y (active or neutral to ground) was ïnvented".
Lucky the only death was the cap itself.
Safety Tip for old amps - if you are not going to get rid of the death cap entirely then seriously consider replacing it with a Class Y Safety rated cap of the same value.
Cheers,
Ian
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Stevem
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Hu
The amp is a 76 that came with a grounded cord .
If it was not for the end of the cap that gave when it blew all its foil rap out it what have blasted it all right into the recto diodes!
If it was not for the end of the cap that gave when it blew all its foil rap out it what have blasted it all right into the recto diodes!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Leo_Gnardo
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- Location: Dogpatch-on-Hudson
Re: Hu
Yes I've had those ceramic-cylinder Ampeg caps go whizzing across the chassisStevem wrote:The amp is a 76 that came with a grounded cord .
If it was not for the end of the cap that gave when it blew all its foil rap out it what have blasted it all right into the recto diodes!
, leaving a sparking trail of aluminum foil in their wake. Had enough "fun" with that, now I just cut 'em out on sight. Save the fireworks for Independence Day. 1970's there was no safety regs, they just put in a tough cap reckoned to take the punishment. 40 years older, not so much. Snip snip, gone!down technical blind alleys . . .
Re: Ampeg mistake
Technically not illegal (way back then) because ClassY/X or similar came later.
And read cap rating again, in that case "120V" does NOT mean 120V DC like on the ones we use inside the amp, but a special 120VAC UL rated type.
I''ve never seen the detailed spec, but from seeing various examples it had to stand 2X the Peak AC voltage or better.
I've seen 400V (DC) caps in 110/120V mains and here (220VAC) .047 or .022x630V is a popular and accepted value.
My personal favorite here was .01x1000 or 1600VDC , good quality (Siemens, today Epcos), never ever had a problem.
If those Ampeg caps are known to blow regularly, then they definitely were poorly rated.
And read cap rating again, in that case "120V" does NOT mean 120V DC like on the ones we use inside the amp, but a special 120VAC UL rated type.
I''ve never seen the detailed spec, but from seeing various examples it had to stand 2X the Peak AC voltage or better.
I've seen 400V (DC) caps in 110/120V mains and here (220VAC) .047 or .022x630V is a popular and accepted value.
My personal favorite here was .01x1000 or 1600VDC , good quality (Siemens, today Epcos), never ever had a problem.
If those Ampeg caps are known to blow regularly, then they definitely were poorly rated.
Design/Make/Service Musical stuff in Buenos Aires, Argentina, since 1969
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Stevem
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......
The cap was stamped with a 125 volt ac rating, no DC listed at all.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: ......
Well, that's probably just a bog standard cap failure, unless they bought a batch of poorly made caps. Even recently, there are too many examples of parts failure with lowest-bidder parts that supposedly met a certain standard.Stevem wrote:The cap was stamped with a 125 volt ac rating, no DC listed at all.
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Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
.....
Yeah, but our wall outlets are 120 RMS , peak is way more than that and that's what took out that cap with only a 125 volt rating!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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martin manning
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- Location: 39°06' N 84°30' W
Re: .....
Stevem wrote:I forgot to post that this vt40 I was working on had a blown up original death cap, this think left the factory with a cap rated for 120vac!
But "VAC" is an RMS voltage, no?Stevem wrote:Yeah, but our wall outlets are 120 RMS , peak is way more than that and that's what took out that cap with only a 125 volt rating!