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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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6AU6 Plate to Grid short
My old tube tester confirmed a short in this 6AU6 tube, which explains
why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. |
#2
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6AU6 Plate to Grid short
On Tuesday, November 29, 2016 at 7:11:58 AM UTC-5, wrote:
My old tube tester confirmed a short in this 6AU6 tube, which explains why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. The short answer is NO. 6UA6 tubes are still available in the marketplace. Dan |
#3
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6AU6 Plate to Grid short
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#5
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6AU6 Plate to Grid short
On 11/29/2016 07:18 AM, wrote:
On Tuesday, November 29, 2016 at 7:11:58 AM UTC-5, wrote: My old tube tester confirmed a short in this 6AU6 tube, which explains why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. The short answer is NO. 6UA6 tubes are still available in the marketplace. Dan There's a very interesting video tour of Mullard's Blackburn Valve Factory that explains a lot of stuff like that: https://www.youtube.com/watch?v=GDvF89Bh27Y Cheers Phil Hobbs |
#6
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6AU6 Plate to Grid short
On Tuesday, November 29, 2016 at 7:11:58 AM UTC-5, wrote:
My old tube tester confirmed a short in this 6AU6 tube, which explains why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. Before I was forced to try something that drastic I'd redesign it for a transistor. Here is an ebay listing for an NOS tube for $4 including shipping. He has four of them if you want to forestall drilling into your tube for a few decades... http://www.ebay.com/itm/Philco-6AU6A...AOSwal5YEXx 7 |
#7
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6AU6 Plate to Grid short
On Tuesday, November 29, 2016 at 7:11:58 AM UTC-5, wrote:
MUCH Snippage a) Nothing you have 'at home' will create sufficient vacuum for what you propose. b) Even if you have a source of Barium to replace the original 'getter', you would have to remove the envelope entirely to install it. c) 6AU6 tubes are common, very common. I have at least a dozen in my tube stash. Our club sells them tested and good in the $2 range. d) And the chances are very likely unless you are a micro-surgeon, that you will screw something up in the process anyway. Peter Wieck Melrose Park, PA |
#8
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6AU6 Plate to Grid short
wrote in message ... My old tube tester confirmed a short in this 6AU6 tube, which explains why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. Troll score - 3 of 10 Please try to up your game. |
#9
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6AU6 Plate to Grid short
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#10
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6AU6 Plate to Grid short
On Tue, 29 Nov 2016, Ralph Mowery wrote:
In article , says... wrote in message ... My old tube tester confirmed a short in this 6AU6 tube, which explains why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. Troll score - 3 of 10 Please try to up your game. Iknow this is trolling, but on youtube I ran across a person that was building small tubes such as this at his house. Very interisting to watch him do it. Long time ago and I don't recall the title or where to find it. There was one from Europe a few years ago that got a lot of travel. But in 1964 or 65 there was an article in QST about an Argentinian who wa making tubes. He was mostly interested in making his own power tubes for transmitters, so his own design rather than copying well known tubes. They talk about it in the areas where antique radios are discussed, there's a certain plateau one has to reach and most aren't up there yet. What I wonder is if it was "common" in the early days of tubes. People made all kinds of things, I've read that they'd get some quartz and make their own crystals even and certainly people made their own paper capacitors in the early days, so making a tube might not be out of the norm, so long as someone had the resources. It might perhaps have been more "common" back then, since tubes were still new, but perhaps not. But it would be interesting to see if there were articles about making your own tubes back then. Getting enough vacuum seems to be a common issue, at least once you have some success as a glass blower. I haven't seen much about whether people are making triodes or anything more complicated. Michael |
#11
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6AU6 Plate to Grid short
Michael Black wrote:
Ralph Mowery wrote: I know this is trolling, but on youtube I ran across a person that was building small tubes There was one from Europe a few years ago that got a lot of travel. You're probably remembering this one https://youtu.be/EzyXMEpq4qw People made all kinds of things There was a more recent one of someone making larger nixie tubes than the NOS ones https://youtu.be/wxL4ElboiuA |
#12
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6AU6 Plate to Grid short
A great number of sites on the Net provide old tubes.
There also exist tube regenerators which can remove short-circuits. It also works for old CRT tubes. But it is rather expensive and you have to find a shop which owns one. a écrit : My old tube tester confirmed a short in this 6AU6 tube, which explains why a resistor fried on it's socket. I know replacement is the best solution, but old tubes are getting hard to find. I always figured shorts inside tubes occur because the parts inside are loose. Is it possible to drill into the glass, and use a pin to align the parts so they are not shorted, then shoot some epoxy inside to keep these parts solid, so they cant touch anymore? Yes, I know they need a vacuum, so I'll have to use a vacuum cleaner to suck out the air, then epoxy the hole shut. |
#13
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6AU6 Plate to Grid short
Still won't work. You better come up with a plan for fixing the
resistor, too. |
#14
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6AU6 Plate to Grid short
Michael Black wrote:
There was one from Europe a few years ago that got a lot of travel. But in 1964 or 65 there was an article in QST about an Argentinian who wa making tubes. He was mostly interested in making his own power tubes for transmitters, so his own design rather than copying well known tubes. They talk about it in the areas where antique radios are discussed, there's a certain plateau one has to reach and most aren't up there yet. What I wonder is if it was "common" in the early days of tubes. People made all kinds of things, I've read that they'd get some quartz and make their own crystals even and certainly people made their own paper capacitors in the early days, so making a tube might not be out of the norm, so long as someone had the resources. It might perhaps have been more "common" back then, since tubes were still new, but perhaps not. But it would be interesting to see if there were articles about making your own tubes back then. Getting enough vacuum seems to be a common issue, at least once you have some success as a glass blower. I haven't seen much about whether people are making triodes or anything more complicated. Michael There was alot of tube bootlegging going on in the early 20s. I'm think a guy with the specialized equipment to make one tube would be strongly tempted to make a dozen or hire people and make hundreds or more. |
#15
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6AU6 Plate to Grid short
"Iknow this is trolling, but..."
I am not so sure. There are alot of people, especially in the US, who think you can DIY things you simply can't. It is a matter of knowing the process.. At this point I wonder if tubes like a 6AU6 are bombarded like CRTs were. At one point I thought about trying to build an EMPG but after some research (not posting on a forum) found out it is just about impossible without alot of money and resources. I have come up with alot of ideas that simply were not practical, and the ones that were were either unsaleable or already done and at the very least unpatentable. Also, some people have no idea how to think things through. Even with an adequate vacuum pump, just how do you get the epoxy on there ? Tubes, before final manufacturing processes have a tube through which the vacuum is pulled ad then that is heated right near the seat of the socket, or other end and in the atmosphere the glass tubing collapses and then you cut it off. I am not sure when the getter is applied. And the OP's assumption that one of the suspension components broke is a bit off as well. The 6AU6 is a pentode right ? Does it have the suppressor grid internally tied to the cathode ? (most do) If so the short is more likely caused by one of those fine wires simply breaking. They are held in place by mica sheets so any misalignment could only come from traumatic mechanical shock. now if he has a G1 to plate short then the trauma must have been vertical and just made the whole thing shift down and cause the wires at the bottom going to the actual pins short out. Otherwise the short would read cathode to G2, not plate. Well not necessarily. An excellent exercise in futility for a Tuesday night. Get off the four bucks and buy the tube and replace the resistor. |
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