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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Toroidal mains Tx inrush limiter - retrofit
This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other than poor physical integrity of the lead "welds" to the body (like disc ceramic cap) - will mount on small high temp board and wire into the neutral side of the wiring, with plenty of clear air space around. Other than zero crossing Triac sub-cicuit to delay sw off, not creating ferrite core residual magnetism, and delayed switching on also, any other ways around this phenomenon other than bad practise uprating of the mains fuse? Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? |
#2
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Toroidal mains Tx inrush limiter - retrofit
In article , N_Cook
writes This 300W amp blows correct T3.15A fuses every now and then at sw on. The owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. We have a similar problem at work with cryogenic coolers, which are more or less like a fridge - a compressor and heat exchanger. Like you say, the fuse doesn't blow, just parts cleanly due to inrush surge at switch on. Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Don't see why not. Or a 1 ohm wirewound resistor which will dissipate 3.15W at peak, so use a 5W one. Mount it in free air, of course. will mount on small high temp board and wire into the neutral side of the wiring, Why the neutral? Just curious. Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? I would say they are unsafe for use on mains, simply because they reconnect the current when they heal. If there is an actual fault in the equipment rather than the inrush current blowing the fuse and disabling the supply permanently, it could lead to a fire. -- Mike Tomlinson |
#3
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Toroidal mains Tx inrush limiter - retrofit
On Wed, 30 Mar 2011 13:07:48 +0100, N_Cook wrote:
This 300W amp blows correct T3.15A fuses every now and then at sw on. The owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. Slo Blow? -- Live Fast Die Young, Leave A Pretty Corpse |
#4
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Toroidal mains Tx inrush limiter - retrofit
In article , Meat Plow
writes Slo Blow? He is fitting slo blo, it's what the T in "T3.15A" means. -- Mike Tomlinson |
#5
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Toroidal mains Tx inrush limiter - retrofit
"N_Cook" wrote in message ... This 300W amp blows correct T3.15A fuses every now and then at sw on. The owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other than poor physical integrity of the lead "welds" to the body (like disc ceramic cap) - will mount on small high temp board and wire into the neutral side of the wiring, with plenty of clear air space around. Other than zero crossing Triac sub-cicuit to delay sw off, not creating ferrite core residual magnetism, and delayed switching on also, any other ways around this phenomenon other than bad practise uprating of the mains fuse? Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? I've had a few bits of gear for repair that just seem to have an under-rated fuse. e.g. Mackie SR1530. Try a T4 instead. I even had a Marshall here that had (according to Marshall) the wrong value fuse designed in. It was doing my head in for ages until I phoned Marshall about it. They sent me an uprated fuse and stickers to place on the PCB showing the uprated value. Gareth. |
#6
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Toroidal mains Tx inrush limiter - retrofit
Mike Tomlinson wrote in message
... In article , N_Cook writes This 300W amp blows correct T3.15A fuses every now and then at sw on. The owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. We have a similar problem at work with cryogenic coolers, which are more or less like a fridge - a compressor and heat exchanger. Like you say, the fuse doesn't blow, just parts cleanly due to inrush surge at switch on. Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Don't see why not. Or a 1 ohm wirewound resistor which will dissipate 3.15W at peak, so use a 5W one. Mount it in free air, of course. will mount on small high temp board and wire into the neutral side of the wiring, Why the neutral? Just curious. Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? I would say they are unsafe for use on mains, simply because they reconnect the current when they heal. If there is an actual fault in the equipment rather than the inrush current blowing the fuse and disabling the supply permanently, it could lead to a fire. -- Mike Tomlinson An engineer I know with IBM Hursley has the same problem with large toroid Tx on some research kit, he personally was not aware of the phenomenon of random remnant magnetisation at switch off, then right/wrong polarity mutually coupled across "adds" to the inrush current , until he asked me if I knew. Some more data on this thermistor , green and marked CCK but no info found Passing DC through it , stabilizes at 2.7R with 1.2V across it so 3.2W , ..44R and measuring 115 deg C via IR "pyrometer" |
#7
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Toroidal mains Tx inrush limiter - retrofit
2.7 amp , not 2.7R
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#8
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Toroidal mains Tx inrush limiter - retrofit
On Wed, 30 Mar 2011 14:56:24 +0100, Mike Tomlinson wrote:
In article , Meat Plow writes Slo Blow? He is fitting slo blo, it's what the T in "T3.15A" means. Thought the T mean the size. -- Live Fast Die Young, Leave A Pretty Corpse |
#9
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Toroidal mains Tx inrush limiter - retrofit
In article , Meat Plow
writes Thought the T mean the size. T for Time delay ) -- (\__/) (='.'=) (")_(") |
#10
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Toroidal mains Tx inrush limiter - retrofit
On Wed, 30 Mar 2011 18:52:48 +0100, Mike Tomlinson wrote:
In article , Meat Plow writes Thought the T mean the size. T for Time delay ) I just thought of something. Ambient temperature does affect current carrying capability. Maybe this has some influence on Cook's problem? High ambient temperature over a period of time weakens the fuse material and after current influx causes the fuse core to 'twitch' many times it finally breaks. Not unlike a light bulb. -- Live Fast Die Young, Leave A Pretty Corpse |
#11
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Toroidal mains Tx inrush limiter - retrofit
By the way,
What's the antithesis of Occam's razor? |
#12
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Toroidal mains Tx inrush limiter - retrofit
Religious superstition?
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#13
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Toroidal mains Tx inrush limiter - retrofit
On Mar 30, 8:22*am, "Phil Allison" wrote:
"Nutcase ****ing Kook" ***You ridiculous, ****ing nut case *!!! ** ****ing stupid. ***You * *ABSOLUTE * DONKEY'S * ASS !!! * *** Wot a *COLOSSAL *MORON *!!! ***You ****ing stupid ASS !!!!!!! ..... *Phil I'm sure I'm one of the very few who haven't plonked you yet and can actually view any of your posts (and realize that by quoting you I am actually giving you some exposure), but I have to say that you are one smooth talker Phil. You must be quite the hit with the ladies. Edwin |
#14
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Toroidal mains Tx inrush limiter - retrofit
"Stroonz" ** Bugger off - IMBECILE |
#15
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Toroidal mains Tx inrush limiter - retrofit
"Mike Tomlinson" We have a similar problem at work with cryogenic coolers, which are more or less like a fridge - a compressor and heat exchanger. Like you say, the fuse doesn't blow, just parts cleanly due to inrush surge at switch on. ** What absolute crap !!! The magnetic inush suge of a toroidal tranny plus filter caps charging will easily SPLAT an undesized "slo blo" or " fast " fuse completely. Don't see why not. Or a 1 ohm wirewound resistor which will dissipate 3.15W at peak, so use a 5W one ** ROTFL - what difference is 1 ohm gonna make ?? will mount on small high temp board and wire into the neutral Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? I would say they are unsafe for use on mains, simply because they reconnect the current when they heal. If there is an actual fault in the equipment rather than the inrush current blowing the fuse and disabling the supply permanently, it could lead to a fire. ** Polyswitches all start of with a very low resistane then go high after some time at high current - mains voltage rated examples do not exist. .... Phil |
#16
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Toroidal mains Tx inrush limiter - retrofit
"Nutcase ****ing Kook " An engineer I know with IBM Hursley has the same problem with large toroid Tx on some research kit, he personally was not aware of the phenomenon of random remnant magnetisation at switch off, then right/wrong polarity mutually coupled across "adds" to the inrush current , until he asked me if ** Shame you have totally mis-informed him. I knew. ** You know absolutely NOTHING !! ..... Phil |
#17
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Toroidal mains Tx inrush limiter - retrofit
"Mike Tomlinson" T for Time delay ) ** The "T" stamp on fuses stands for the German word " Trage" = lazy. ...... Phil |
#18
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Toroidal mains Tx inrush limiter - retrofit
"Gareth Magennis" What's the antithesis of Occam's razor? ** Conspiracy theories - cos they always involve many unnecessary, unsupported and improbable assumptions. ..... Phil |
#19
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Toroidal mains Tx inrush limiter - retrofit
Polyswitches all start of with a very low resistance,
then go high after some time at high current -- mains-voltage rated examples do not exist. Then what causes my bulk eraser to shut off when it overheats -- then come back when it cools off? |
#20
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Toroidal mains Tx inrush limiter - retrofit
Hehe... I think you and I are the only two folk who can see your
posts Phil. Don't worry, I won't plonk you. There is precious little else on the web that's as interesting as you. Make sure you come up with a real zinger for me!!!! Edwin |
#21
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Toroidal mains Tx inrush limiter - retrofit
"William Sommer******" Then what causes my bulk eraser to shut off when it overheats -- then come back when it cools off? ** Have a ****ing look. ..... Phil |
#22
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Toroidal mains Tx inrush limiter - retrofit
On 3/30/2011 7:07 AM, N_Cook wrote:
This 300W amp blows correct T3.15A fuses every now and then at sw on. The owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other than poor physical integrity of the lead "welds" to the body (like disc ceramic cap) - will mount on small high temp board and wire into the neutral side of the wiring, with plenty of clear air space around. Other than zero crossing Triac sub-cicuit to delay sw off, not creating ferrite core residual magnetism, and delayed switching on also, any other ways around this phenomenon other than bad practise uprating of the mains fuse? Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? http://www.ametherm.com/inrush-curre...t-limiter.html bob |
#23
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Toroidal mains Tx inrush limiter - retrofit
"boob errs = Google Monkey " http://www.ametherm.com/inrush-curre...t-limiter.html ** Wot a load of utterly irrelevant, mindless drivel. Musta been written by a marketing puke. ...... Phil |
#24
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Toroidal mains Tx inrush limiter - retrofit
On 3/30/2011 9:13 PM, bob urz wrote:
O Other than zero crossing Triac sub-cicuit to delay sw off, not creating ferrite core residual magnetism, and delayed switching on also, any other ways around this phenomenon other than bad practise uprating of the mains fuse? Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? http://www.ametherm.com/inrush-curre...t-limiter.html bob http://www.ametherm.com/inrush-curre...h-current.html |
#25
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Toroidal mains Tx inrush limiter - retrofit
Gareth Magennis wrote in message
news By the way, What's the antithesis of Occam's razor? dunno but talking to a philosopher last week for his take on occam's razor , he put me right in that it is a mistranslation of Occam's raison ... I run science talks locally and he will be talking on the philosophy of science, Nicomachean Ethics, Occam's whatever etc series details http://www.diverse.4mg.com/scicaf.htm |
#26
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Toroidal mains Tx inrush limiter - retrofit
"Nutcase ****ing Kook" dunno but talking to a philosopher last week for his take on occam's razor , he put me right in that it is a mistranslation of Occam's raison ... ** Utter bull****. Kook is such a retarded ****wit, god know how he remembers to ****. ...... Phil |
#27
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Toroidal mains Tx inrush limiter - retrofit
In article
s.com, Stroonz writes You must be quite the hit with the ladies. Given that he seems to be obsessed with ass, I suspect he probably hangs out in his local gay leather bar. -- Mike Tomlinson |
#28
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Toroidal mains Tx inrush limiter - retrofit
In article , William Sommerwerck
writes Then what causes my bulk eraser to shut off when it overheats -- then come back when it cools off? That's a resettable *thermal* fuse, NOT a fuse designed for overcurrent protection. -- Mike Tomlinson |
#29
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Toroidal mains Tx inrush limiter - retrofit
In article , Gareth Magennis
writes What's the antithesis of Occam's razor? Occam's beard? -- Mike Tomlinson |
#30
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Toroidal mains Tx inrush limiter - retrofit
"Mike Tomlinson" ** What a BORING know nothing, ****wit bull**** artist. The LESS you know about a topic - the MORE you feel compelled to talk ******** about it. I call that sort of rampant narcissism: " pommy disease ". Wot a shame it ain't fatal. ..... Phil |
#31
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Toroidal mains Tx inrush limiter - retrofit
"William Sommer******"
I love the fact I have a name that so lends itself to stupid wordplay. Then what causes my bulk eraser to shut off when it overheats -- then come back when it cools off? ** Have a ****ing look. I especially love the way you squirm when backed into a corner. |
#32
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Toroidal mains Tx inrush limiter - retrofit
Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off? That's a resettable *thermal* fuse, NOT a fuse designed for overcurrent protection. I had always thought that at least some polyfuses /were/ resettable. Regardless, thanks for the answer. |
#33
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Toroidal mains Tx inrush limiter - retrofit
"William Sommer****** is a Lying **** " I love the fact I have a name that so lends itself to stupid wordplay. Then what causes my bulk eraser to shut off when it overheats -- then come back when it cools off? ** Have a ****ing look !!!!!!!!!!!!! You STINKING, AUTISTIC ARSEHOLE !!! |
#34
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Toroidal mains Tx inrush limiter - retrofit
"William Sommer******" Some Bull****ting Pommy ****wit. Then what causes my bulk eraser to shut off when it overheats -- then come back when it cools off? That's a resettable *thermal* fuse, NOT a fuse designed for overcurrent protection. I had always thought that at least some polyfuses /were/ resettable. ** A " PolySwitch " is self resetting and so is a " Polyfuse". Same basic device. You ****ing RETARD !!!!!!! ..... Phil |
#35
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Toroidal mains Tx inrush limiter - retrofit
On 3/30/2011 8:07 AM, N_Cook wrote:
This 300W amp blows correct T3.15A fuses every now and then at sw on. The owner left in the last one so I can see it is just "tired" , neat break and 2 constituent parts of fuse wire remaining. Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other than poor physical integrity of the lead "welds" to the body (like disc ceramic cap) - will mount on small high temp board and wire into the neutral side of the wiring, with plenty of clear air space around. Other than zero crossing Triac sub-cicuit to delay sw off, not creating ferrite core residual magnetism, and delayed switching on also, any other ways around this phenomenon other than bad practise uprating of the mains fuse? Are polyswitches used in these circumstances , ie not purely "fuse" action or generic name for devices specific for this purpose? Nigel, Also keep in mind as a possibility that the main filter caps are getting tired, and a bit leaky, so that if the amp has not been switched on for a week or 2, it might have abnormally high inrush current as the caps charge/form back up. Lastly, the older 'spring wire' fuses seemed more tolerant of the inrush current compared to the modern chemically treated wire ones. Maybe use an old style fuse, if you can find one. It would be helpful if you would mention the make and model of the product in your posts. Regards, Tim Schwartz Bristol Electronics |
#36
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Toroidal mains Tx inrush limiter - retrofit
On Thu, 31 Mar 2011 20:55:20 +1100, Phil Allison wrote:
What a BORING know nothing, ****wit bull**** artist Nice self-description. -- Live Fast Die Young, Leave A Pretty Corpse |
#37
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Toroidal mains Tx inrush limiter - retrofit
Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off? That's a resettable *thermal* fuse, NOT a fuse designed for overcurrent protection. I had always thought that at least some polyfuses /were/ resettable. Polyfuses (in the sense of the term I've always heard used) are self-resetting, unless you hit 'em so hard that you damage them. They aren't designed for use at mains voltages/currents, though... at least, I haven't seen any that are. The self-resetting thermal "fuses" that you'd find in a bulk eraser or similar "not intended for a 100% duty cycle - let it cool down!" device are (I think) of the bimetallic type, somewhat akin to what you would find in a traditional wall thermostat. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#38
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Toroidal mains Tx inrush limiter - retrofit
"Tim Schwartz" Also keep in mind as a possibility that the main filter caps are getting tired, and a bit leaky, so that if the amp has not been switched on for a week or 2, it might have abnormally high inrush current as the caps charge/form back up. ** This is rather fanciful thinking. An inrush surge ( on a 240V supply) that will take out a T3.15 fuse has to be in the order of 40 to 50 amps. Toroidal transformers in the range of 220 to 300 VA with rectifiers and filter cap banks will provide such surges almost every time they are switched on. Lastly, the older 'spring wire' fuses seemed more tolerant of the inrush current ** Correct, but hard to find them in other than 3AG size and they are much more expensive. compared to the modern chemically treated wire ones. ** Where did you hear this one ?? The ones I use are said to be made from "plated wire" - meaning a thick tin plating over copper. Some are coil shaped and some are not. It would be helpful if you would mention the make and model of the product in your posts. ** Bloody oath it would. What a colossal ASS Kook is for regularly leaving that crucial info out. ..... Phil |
#39
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Toroidal mains Tx inrush limiter - retrofit
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#40
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Toroidal mains Tx inrush limiter - retrofit
"Grant" They aren't designed for use at mains voltages/currents, though... at least, I haven't seen any that are. Me neither, other thing with polyfuses is that there's approx 2:1 current difference between trigger point and hold point. ** That is utterly misleading !! There are no separate trigger and hold points with PolySwitches. The makers specs allow for some device to device variation in the actual current level that will trigger a RANGE of similar devices to change state and go high resistance. The max current that fails to trip all examples of a given type is called: " I Hold ". The minimum current that will trip all examples of a given type is called: " I Trip". " I Trip " is double " I Hold". For any given device, the trip current is one number. Once a device has tripped, the current needed to HOLD it in the new state is a function of the applied voltage and is generally 5 to 20 times less than the trip current. ..... Phil |
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