Sorry I think this is nonsense.
Parmeko is one of those manufacturers you can abuse the living daylights out of.
They have massive built in margins.
These are not cr.p Shenzhen stuff, they are the biz!
The parts they made are some of the finest transformers in the world - ultra conservatively rated for mil use, which is why they are oil filled.
I know their O-F transformers, as well as Gardners, as I have an almost identical PT from Gresham like the Pmk Neptune series.
It's bomb proof as was the other Parmeko PT I fitted in a big 60W guitar amp.
(You know PAR...- was part of Partridge, that says it all).
What has probably happened is the dreaded unlucky winding insulation failure internally to ground.
I saw this happen on a UTC swinging choke which was potted in tar.... It really stank, but lucky I had a spare!
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Thanks sarcastic1.
I'm just a novice hobbyist with no previous experience or knowledge about Parmeko. I was about to get rid of 3 more Parmeko chokes and a power transformer that are still functioning well. Based on your response, I'll reconsider.
J-P, your response to sarcastic1 is sarcastic, right? 🙂. I only ask, because I don't want to repeat the failure. If I can avoid another meltdown by using the within their stated operating, I'll keep them in service. If it is another matter, like just degradation of the insulation through the decades, I'll not use them again.
cheers.
I'm just a novice hobbyist with no previous experience or knowledge about Parmeko. I was about to get rid of 3 more Parmeko chokes and a power transformer that are still functioning well. Based on your response, I'll reconsider.
J-P, your response to sarcastic1 is sarcastic, right? 🙂. I only ask, because I don't want to repeat the failure. If I can avoid another meltdown by using the within their stated operating, I'll keep them in service. If it is another matter, like just degradation of the insulation through the decades, I'll not use them again.
cheers.
The failure is likely because you used the part out of specification but that should be no surprise is it? A 60 mA coil/choke will practically live forever when used at let's say 30 mA. Underspecced with regards to the value of coils won't damage them, using them underspecced with regards to the current rating is not clever. It is somewhat unusual to think the part has failed just like that whilst knowing is has been severely overloaded. That is like letting tubes fall off the table and then blame the glass quality as they broke.
Even mil specced stuff goes kaputt when being abused/overloaded. The brand name has not much to do with that with Parmeko being a fine brand standing out. The PCB's are not nice but if you use them correctly the stuff won't be in the environment. Throwing fine Parmeko stuff away will cause the PCB's to end up somewhere. Counterproductive and not green!
Don't repeat the very clear user error. Please avoid "just doing something". Simply use stuff the tech way, check specs and calculate/measure/verify what you build. Replace if stuff is overloaded.
And eh .... I suggest a fuse in the B+........
Even mil specced stuff goes kaputt when being abused/overloaded. The brand name has not much to do with that with Parmeko being a fine brand standing out. The PCB's are not nice but if you use them correctly the stuff won't be in the environment. Throwing fine Parmeko stuff away will cause the PCB's to end up somewhere. Counterproductive and not green!
Don't repeat the very clear user error. Please avoid "just doing something". Simply use stuff the tech way, check specs and calculate/measure/verify what you build. Replace if stuff is overloaded.
And eh .... I suggest a fuse in the B+........
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It's pretty simple: With two chokes you can often place them where one single big one simply does not have enough space to fit in. And I did write that.
I suggest that comment is nonsense. The OP had the choke winding dissipating 3x its max rated power dissipation. It is a physically small choke. The Neptune range came out in 1951, so the part could be up to 70 years old. The part leaked at the bushings.
If there was an insulation failure then the OP may be able to confirm that, and it is also likely that any such failure was a direct result of insulation degradation due to heat stress. The OP may also be able to confirm the choke winding DCR, to better indicate what the nominal max rated dissipation was, and what dissipation it could have been exposed to.
I hate this stupid greenie nonsense which seems to emerge every 5 mins!!!
If you were really worried about that dumb environmental bla bla you shouldn't be even using components stuffed with barium and who knows what else...as well as all that lead in the glass and solder!
That really smacks of cherry picking at its worst.
As for transformer failures I have plenty to show inc some old Bogen PSU ones which were designed to give 2000V AC across the secondaries.
Guess what?
They both arrived DOA when I bought the amps....both in HV winding shorts, not in heaters and other stuff.
ie.
In my opinion the overwhelming majority of insulation failures I have seen come from overvoltage, nothing to do with current overloads.
So if you are that concerned you simple put the choke in the earth return not in the positive line at all.
So what?
They weren't used for anything other than Mil gear until well into the 70s.
I am running some old amps from 1949.
My every day units are monoblocs from 1964.
All OEM inc the output valves, now knocking on 60yrs old like many of my friend's Jaguar E types, which are commonly producing easy 30% more power than they ever used to in 1964.
What makes it all possible? Build quality and engineering margins.
What killed one of the old 1949 amps?
Some idiot tried to convert it to convert it to Guitar use, burning out the OPT and the G2 supply choke.
Very likely all giving overvoltage spikes.
It was a mess when I rebuilt it, but I found OEM transformers from 1949 and its now running great, at more than 2x the original output power.
Again if experience lacks, just ask a few radio amateurs,not people on here!
hams know a lot more about running components well outside their ratings....look what they used to do to 807s for any further proof.....running them red plating for years on end with no hassle at all!
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Yeah running stuff outside their specs is cool and clever. Specifications and ratings are just social constructs meant to annoy those radio amateurs that know their stuff better than the company that produced the stuff. Never listen to the manufacturer! 🙂
It is no greenie nonsense using parts that are not ROHS or that contain PCB's within their ratings. Using them outside their ratings and destroying them and releasing the PCB's is the most worse for environment (and the DIYer). Just like throwing away perfectly fine working parts that contain dangerous stuff as they already have been produced. These will only have more detrimental effect when throwing them away to have them crushed in some press releasing the oil...
Some ideas from the past were not so good for our world at all. Sinking outdated submarines with nuclear reactors in very deep sea for example. Or building nuclear power plants that have no cooling water heat exchangers and then pollute the cooling water. I think most will know that circular design and avoiding using poisonous materials are among the better solutions to make things really better. In the past people knew but chose the cheapest solution with for instance asbestos and PCB's containing oil in transformers. The use of beryllium is also a nice example. The "greenie nonsense" in this is that other people might be victim of those choices. Well, in fact it is almost always other people that get harmed.
People that work with stuff produced decades ago should be aware what they are working with and they should know the implications when they make errors. Perceived quality of old stuff with old DIYers is that is way better so then design stuff correctly with built in safety to protect that part, yourself and the environment which is all really very simple. Simpler than the other way around anyway.
It is no greenie nonsense using parts that are not ROHS or that contain PCB's within their ratings. Using them outside their ratings and destroying them and releasing the PCB's is the most worse for environment (and the DIYer). Just like throwing away perfectly fine working parts that contain dangerous stuff as they already have been produced. These will only have more detrimental effect when throwing them away to have them crushed in some press releasing the oil...
Some ideas from the past were not so good for our world at all. Sinking outdated submarines with nuclear reactors in very deep sea for example. Or building nuclear power plants that have no cooling water heat exchangers and then pollute the cooling water. I think most will know that circular design and avoiding using poisonous materials are among the better solutions to make things really better. In the past people knew but chose the cheapest solution with for instance asbestos and PCB's containing oil in transformers. The use of beryllium is also a nice example. The "greenie nonsense" in this is that other people might be victim of those choices. Well, in fact it is almost always other people that get harmed.
People that work with stuff produced decades ago should be aware what they are working with and they should know the implications when they make errors. Perceived quality of old stuff with old DIYers is that is way better so then design stuff correctly with built in safety to protect that part, yourself and the environment which is all really very simple. Simpler than the other way around anyway.
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PCB's are only harmful if ingested in some way.
If you got the oil on your hands, wash with soap and water and you'll be fine.
Dispose of it like you would any hazardous waste, don't just chuck it in the garbage can as it'll get into the environment and we don't need any more of that stuff around.
If you got the oil on your hands, wash with soap and water and you'll be fine.
Dispose of it like you would any hazardous waste, don't just chuck it in the garbage can as it'll get into the environment and we don't need any more of that stuff around.
Yeah. Just beware that if the two inductors couple through their magnetic fields you may not get the inductance you expect.
With zero coupling, you'll get L_tot = L1+L2 for series and L_tot = (L1*L2)/(L1+L2) for parallel. I personally would not put inductors in parallel. If you do, you'll need to ensure that they share the current evenly.
If the inductor is in the power supply, I would look at more modern solutions such as B+ voltage regulators. Better performance at a lower price.
Tom
Typical German quatsch!
That's why Germans have never made a F1 car!
Go tell the fairy tales to the USA, while we carry on running stuff at 1-2 x the listed specs...
Dunno if you ever heard of "smokey yunnick" to get an object lesson of what it's like to run dangerous polluting stuff successfully, and to stop the manualitis and greeniedom in its tracks.
I lose patience with all those kraut & sausage eating arguments. 🙄
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Moderators, I am the OP of this thread. It has devolved with racist remarks. Is it possible to have it closed and deleted, please?
You chose the wrong bloke.
I'm not Russian, as if I cared....
As for remarks about Ukrainian NPP, and a pretty much deliberate attempt to blow themselves up, nothing quite like showing total technical ignorance is there? 🙄
As far as I am aware badging a car with "Mercedes" has F-A to do with actually doing the engineering in Northampton England, but there you go,- nothing like ignorance on that score is there, as well?
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