Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubesornothing on May 30, 2010, 01:55:17 pm
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In looking at the digikey catalog, a circuit breaker, which fits in the exact same opening, and it the same size as a fuse holder is a whopping $3.22. Why are we not using these instead of fuses?
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Because clueless users will reset the breaker without wondering why it opened...
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That's right, they will reset the breaker over & over until it is worn out.
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Yeah, I thought about that, but the clueless user is also likely to keep shoving bigger and bigger fuses into the fuse holder, until they start shoving in tin foil.
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I have an assortment of 15A and 20A fuses, some rated for only 32V that I have pulled from tube amps. Seems to be popular. Sometimes I find a Radio Shack or Home Depot receipt in the cabinet plus extra 20A fuses. So maybe a breaker would stop that.
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Yeah, I thought about that, but the clueless user is also likely to keep shoving bigger and bigger fuses into the fuse holder, until they start shoving in tin foil.
Sure, but even in California it's then their responsibility...
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Do you have a Digikey part# for a circuit breaker to fit in a Fender Fuse holder hole ?
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I had a breaker in my Traynor YBA1 & YBRM. Bass master & Reverb master. Tin foil! Boy looking back that was one of the stupid things i did back in the 70's
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I had a breaker in my Traynor YBA1 & YBRM. Bass master & Reverb master. Tin foil! Boy looking back that was one of the stupid things i did back in the 70's
Not if the foil is trimmed to the "proper" width. 1mm=1A :huh: Kidding, of course...
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Here is a 5A one I ordered for my Variac. PB186-ND
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Yeah, I thought about that, but the clueless user is also likely to keep shoving bigger and bigger fuses into the fuse holder, until they start shoving in tin foil.
I would think smoke would be pouring out before they got to the tin foil.
Could always use the foil to redirect the smoke. :cry:
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a tin foil is fine, as long as the amp works good...........
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I think I have a couple of aviation circuit breakers somewhere that I keep meaning to use. But I think they're rated at too-high amperage for most guitar amps.
These are the type that have a circular button that pops out from the panel when the breaker trips. You push the button back in to reset it.
They're neat, I *think* they're expensive, but I rarely pop fuses so they're a bit superfluous.
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I think I have a couple of aviation circuit breakers somewhere that I keep meaning to use. But I think they're rated at too-high amperage for most guitar amps.
These are the type that have a circular button that pops out from the panel when the breaker trips. You push the button back in to reset it.
They're neat, I *think* they're expensive, but I rarely pop fuses so they're a bit superfluous.
I've got an old Sunn 0))) Model T with a circuit breaker - it's a button like one you're describing, I think. Never had to reset it :grin:
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I think I have a couple of aviation circuit breakers somewhere that I keep meaning to use. But I think they're rated at too-high amperage for most guitar amps.
I picked up a BF bassman 50 not too long ago, previous owner 'bragged' about upgrading the fuse with aviation cb. It was rated at 5 Amp. That's 2 1/2 times the fuse size.
The amp now has a Fender replacement fuseholder, along with new filter caps and diodes.
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I saw them on ted weber's site a couple of years ago ($1.50 for the 2A and less ones), and gave them a try. I like them, and have been using them on new builds since then. when I had a rectifier diode short on a lightning reverb, the 1A breaker worked as advertised (and nothing else blew up).
I assume the weber ones are slow-blo (I saw both versions at mouser).
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I just installed on in my experimental platform -- got tired of driving 50 miles round trip to Radio Shack every time I popped a fuse, only to find "sorry, we're all out of slo-blo..." I had some concerns about the reaction time, but I just powered up and it works just fine. Here's the one I used:
http://www.newark.com/jsp/search/productdetail.jsp?SKU=56F873 (http://www.newark.com/jsp/search/productdetail.jsp?SKU=56F873)
I agree that I wouldn't use one in an amp built for sale, but it's a perfect solution for this application, where blowing fuses is the norm.
To add one more to the 'oh shit!' stories . . .
Back around 1971 or so, I had just acquired my first Marshall - a plexi 100W bass head. Couldn't afford a cabinet, but took it to a party where I plugged it into a friend's 2 PA columns. (Impedance? What's impedance?)
A tab of sunshine and we were really rocking out a cover of All Along the Watchtower when, suddenly . . . no sound. BUMMER!
Fuse was blown. No replacements on hand. What do do?
A pair of wire nippers and a metal hanger solved the problem handily.
We wailed for another several minutes, even had our own impromptu smoke generator!
RIP my poor Marshall!
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The funny thing is that few years ago, when in Italy the old "electricity meter"* was substituted with the new electronic meters all this new meters resulted to be very sensible to the max KWh the company setted on it so they very often disconnect the circuit of the house from the line
This forced the people to have to manually re-enable the counter, lifting the small lever manually
A small accessory immediately became of great use, a small box with a mechanism through which a cord pulled, in an automatic way, the small lever counter reconnecting the system to the line
This without that anybody cared that this was forcing the operation over the allowed limit :icon_biggrin:
K
*I don't know if this is the right term in english, I mean the meter that say to the company how many KW is your consumption of electricity in one mount
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> the meter that say to the company how many KW is your consumption of electricity
Electric meter, technically a Watt-Hour meter (usually KiloWattHour, a watt-hour is very small, like buying pasta one at a time).
http://www.rvparksupplies.com/mm5/graphics/00000001/METER1.jpg (http://www.rvparksupplies.com/mm5/graphics/00000001/METER1.jpg)
http://t1.gstatic.com/images?q=tbn:ANd9GcSkh91sg9wlGWsUVSRYW0W2H3m3U-qpnW9THKqUFhsBjBbgXkme (http://t1.gstatic.com/images?q=tbn:ANd9GcSkh91sg9wlGWsUVSRYW0W2H3m3U-qpnW9THKqUFhsBjBbgXkme)
http://en.wikipedia.org/wiki/Electricity_meter (http://en.wikipedia.org/wiki/Electricity_meter)
http://pabook.libraries.psu.edu/palitmap/ElectricMeter.html (http://pabook.libraries.psu.edu/palitmap/ElectricMeter.html)
> they very often disconnect the circuit of the house from the line
Here, the traditional electric meter would NEVER disconnect the load, even if the wires were burning up.
(They now have "smart" meters, nobody comes to read them, but even these do not have the LARGE contacts needed to disconnect heavy loads.)
If I don't pay my bill, I think they disconnect the wire at the pole or remove the meter. This almost never happens. Certainly not in winter and probably not in summer heat; people and pipes can freeze. Also people have medical equipment. (They are supposed to register life-support loads, but sick people sometimes don't.) The electric company will make many attempts to contact a customer before cutting the power.
In future, extra-smart meters *may* disconnect *selected* loads. Water-heating can usually be done later. Air-conditioners can be staggered so they don't all start/run at once. But that level of control won't happen soon, and maybe never.
I don't like the idea of electric service which can "pop out" on small overload.
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That's right, they will reset the breaker over & over until it is worn out.
Either that or tape the breaker shut, the circuit breaker equivalent of the 20A fuse. I think a circuit breaker really isn't a bad idea. It can be abused or misused just like the 20A fuse but there's no safeguard against stupidity. Great for those one off times that a fuse blows when there really isn't a circuit defect. What I really hate are those internal clip mounted fuses that you have to pull the chassis to replace. My Sovtek/Splawn Mig60 has three fuses. The mains fuse is on the rear panel. The HT and screen supplies are fused separately and located internally on a power supply board. I guess it's good in a way. Prompts you to look things over while you are in there to make sure nothing has released smoke and protects the non-tech types from themselves.
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I use breakers exclusively. Yes, someone may tape them down, but the same person will bypass a fuse. I use the 1/4 inch. In the case of a fender chassis, this opens up the fuse hole for anything else I want to make switchable or a pot to it. On one of my 5f4's and my tweed bassman I have used the fuse hole to install a master.
The sad fact is a guitar player who doesn't understand the fuse shorted for a reason will bypass it and keep on playing. May not that sad of a fact as it does give extra work to amp repair shops and increases the profit. The only way to idiot proof is to put all the fuses in the chassis and cover them and place a warning sticker that states there are no serviceable parts in this component and use rivets to hold the cover on. This is not to say I haven't done plenty of idiotic things myself, but I have never bypassed a fuse in an amp.
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As soon as you invent something that's idiot-proof, someone will come along and invent a bigger idiot.
:BangHead:
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The electric company will make many attempts to contact a customer before cutting the power.
You don't live in Calgary! They will cut the power and let the place freeze solid without a second thought here.They are greedy to the max....Enmax is the utility company here.They care about nothing except their money.
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Been a while, but just revisiting old threads ... I love WAY out in the sticks in northeastern PA -- STILL no cell phone service up here ... anyway, can't even estimate the times I've run out in a blizzard, driven 25 miles to the nearest Radio Shack, only to have the PFY (Pimple-Faced Youth) look at me like I just emerged from a spaceship when I asked for SLO-BLO fuses ...
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As an update - the I-t characteristic of that W28 series of thermal circuit breakers makes them a close equivalent to a "very" time-lagged fuse - so they take quite a lot longer to trip than a T or slow blow equivalent fuse of same current rating. That may be good, or it may allow parts to fail - a bit of a guess on that front for people making a quick swap-out cos they are sick of replacing fuses, although at least the datasheet provides a nice set of spec limits to help someone design them in for an amp.
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Good to know -- will probably just use the breakers during development and then replace them with a fuse. lately I've been using these really neat little IEC inlets with power switch, fuse, and an extra fuse in a little drawer, all in the same unit.
As an update - the I-t characteristic of that W28 series of thermal circuit breakers makes them a close equivalent to a "very" time-lagged fuse - so they take quite a lot longer to trip than a T or slow blow equivalent fuse of same current rating. That may be good, or it may allow parts to fail - a bit of a guess on that front for people making a quick swap-out cos they are sick of replacing fuses, although at least the datasheet provides a nice set of spec limits to help someone design them in for an amp.