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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE! |
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#21 |
Rest in Peace
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
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Back in ancient times we used to have a very effective glue-free fix.
If the plastic-with-pins base was simply loose (i.e tension on the pinch wires was just slack) we'd wind a piece of 16swg copper wire round the glass at base level. This would force the base downwards, take up the slack, and stiffen the whole thing up. The shape of the glass was invariably "sympathetic". One or at most two turns, with a drop of solder on the twist to hold it firm, usually solved the problem. |
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#22 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 14,463
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Doesn't that put a lot of stress on the wires (and the seals where the wires enter the glass) though?
N. |
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#23 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 4,275
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I rebased a PM24A which had a badly cracked base. Although loose, the base had to be cut off as the glass has a substantial rim. Using the wire as a wedge would possibly only pull the rim back against the shrunken adhesive.
I have also successfully used the acetone and nail varnish trick recommended in an old thread. |
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#24 |
Triode
Join Date: Jun 2007
Location: Copenhagen, Denmark
Posts: 48
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What did the factories use for securing the bases ?
Can't we use the same ? Martin |
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#25 |
Heptode
Join Date: Oct 2004
Location: Bristol, UK.
Posts: 837
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I believe they used a shellac based cement. It softens or disintegrates completely if you soak it with an organic solvent such as meths or acetone.
I don't know what the filler was, but it may have been wood flour. You can get shellac sanding sealer at DIY places. Pete. |
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#26 |
Banned
Join Date: Aug 2006
Location: London, UK.
Posts: 48
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Why not use ceramic tile cement,this has worked great for me!
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#27 |
Nonode
Join Date: Jan 2003
Location: Bradford on Avon, Wiltshire, UK.
Posts: 2,785
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Car exhaust filler?
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"Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly." |
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#28 |
Hexode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 430
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I have re-attached the loose plate or grid caps using furnace cement- (Used here to repair cracks in stoves & furnaces. Very high heat stuff).
No problems so far on horizontal ouotput tubes, or transmitting tubes like 807 & 6146's. I resolder the wire with silver solder also. |
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#29 | |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,198
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Regds, Russell W. B. G4YLI. |
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#30 |
Pentode
Join Date: Nov 2004
Location: East Sussex, UK.
Posts: 242
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I've got the problem with one of the PX4s in my Beau Decca amp - but there's also a loose connection which responds to the valve being moved. How do I repair the wire to pin connections - simply resolder them?? Bryan
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#31 |
No Longer a Member
Join Date: Nov 2005
Location: Pocklington, East Yorkshire, UK.
Posts: 171
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An old way I read about of securing a loose base back to a valve is to make a collar from a bicycle inner tube. If you cut out a piece across the section, about a 1 1/2", you end up with a wide rubber band that can be slipped over the base and up over the glass, so half of the rubber is over the base and half over the glass.
Fully reversible too. Never tried it but it should be OK as long as the valve doesn't get too hot. Keith |
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#32 |
Pentode
Join Date: Nov 2004
Location: East Sussex, UK.
Posts: 242
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Thanks - but what about the electrical connections?? Bryan
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#33 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 5,688
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Hi Bryan, it is sometimes possible to re-flow the solder at the end of the pin. However if the base is also loose it would be better to remove the solder from all pins, remove the base, extend the wires (suitably insulated) and then resolder to the clean wire.
This trick is in several of the FJ Camm books Ed |
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#34 |
Hexode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 430
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I have had good luck using both Super Glue and GE RTV silicone seal ( aquarium grade- as the outgasses from it don't harm electronic parts) to tighten up the bases.
As far as the grid/plate caps go, I found using furnace cement (Handles high temps very well) to glue the caps back on works well, and then silver soldering the wire back on to the cap if needed. I personally know one "local" used tube dealer who uses Super Glue on all the ones he sells here in the States. |
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#35 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,260
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I must admit, I was worried by the report that 'superglue' was the worst adhesive to use on loose valve bases
![]() ![]() Phil
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Phil “The place where optimism most flourishes is the lunatic asylum” - Havelock Ellis |
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#36 |
Hexode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 430
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I have used furnace cement with good luck to glue the top plate/grid caps back on the tubes.
I don't see why it would not work on the bases as well. The 807's & 6146's I tried it on have held up real well running "slightly" over the recommended current for plate load design ratings. Watching the plates turn from red to white with the key down is entertaining ![]() |
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#37 |
Pentode
Join Date: Nov 2004
Location: East Sussex, UK.
Posts: 242
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Thanks - I fixed this (some time ago!) by carefully unsoldering the base, fixing the loose connection, resoldeirng it and then runnig Araldite around the base. Job done!! Bryan
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#38 |
Pentode
Join Date: Aug 2005
Location: Dublin, Ireland.
Posts: 157
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hello, ive used fernox ls-x , on an old mullard valve in my philips 525a , also the top connection which was also loose , seems to have done the job no sign of melting , this compound is really for sealing plastic water pipes , best regards maitiu.
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#39 |
Banned
Join Date: Dec 2003
Location: North London, UK.
Posts: 6,168
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Fernox LS-X is a silicone sealant with quite a strong vinegar (acetic acid) smell. It's designed as a plumbing leak sealant and jointing compound though I would have doubts about using it on plastic pipes. A light smear on a compression joint or fibre washer can work wonders. I don't know if the acetic acid could be harmful to a valve.
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#40 |
Hexode
Join Date: Feb 2006
Location: Diss, Norfolk, UK.
Posts: 317
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I have succesfully used Loctite Body Filler (from Halfords) for some years on KT66s and the like. It's easy to get and dries quickly.
Take care with the silicone sealants most of them give off gas that is corrosive to copper although you can get special types from Farnell. Trevor |
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