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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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29th Jun 2022, 6:20 pm | #21 | |
Rest in Peace
Join Date: Apr 2008
Location: London, UK.
Posts: 2,508
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Re: Faulty valves - Scrap or keep?
And unless generously supplied with known faulty valves, might be repurposing usable items in a way that removes them from ever being available for repairs.
Quote:
Unlike most types of valve, most varieties of mug are still being manufactured and a new mug is likely to be better than a repaired one. Non-operational preserved vehicles can be exhibited with tyres that are no longer suitable for road use, but would look odd with bare rims. Truly life-expired tyres are often perished throughout and could not be used in any way to contribute to future repair / conservation efforts, which is not the same for valve electrode assemblies. I have some n/g lamps that look generally intact but don't work. I can let people handle them without fear of losing something valuable if dropped. This forum has an emphasis on making things work; sets and parts are seen mainly in the light of whether they are useful towards this aim. This is not universal in the study of historical objects. For example, dinosaur skeletons don't 'work' and they've already been documented and studied, and once upon a time there were thousands of them around. So by some of our metrics are not worth keeping. People presumably used to throw dead Loewe 3NFs away once the repair service came to an end. |
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29th Jun 2022, 8:22 pm | #22 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
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Re: Faulty valves - Scrap or keep?
I might keep worn out tyres if still marginally useful for example to fit to a vehicle in order to tow it away for scrap, much cheaper than a recovery truck.
I would not keep a broken mug unless so rare as to be still interesting even if broken. I would keep dead light bulbs if rare and interesting but not otherwise. Cant think of a reason to keep dead fuses, except perhaps very short term as a reminder to purchase new ones. Or in the workplace to give to the store keeper "please order more of these" |
1st Jul 2022, 11:21 am | #23 |
Pentode
Join Date: Dec 2005
Location: Denton, Manchester, UK.
Posts: 186
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Re: Faulty valves - Scrap or keep?
So, you have a couple of PX4s apparently dead. Play around with them, re-solder the pins
and whatever else you can think of, still don't work. Did you re-solder them well enough?Is there something wrong with your test gear? Must be duff, might as well bin them.... or keep them, just in case? |
2nd Jul 2022, 10:49 am | #24 |
Nonode
Join Date: Oct 2010
Location: Gloucester, Glos. UK.
Posts: 2,149
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Re: Faulty valves - Scrap or keep?
I have a few dead valves , none of which are rare but they are interesting shapes and filaments but i certainly dont keep every dead valve that comes my way.
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2nd Jul 2022, 11:26 am | #25 |
Hexode
Join Date: Apr 2011
Location: Grove Park, SE London
Posts: 382
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Re: Faulty valves - Scrap or keep?
Could they be useful as dummies to check for shorts? I have been building a small radio that uses the mini battery types and I had a short which wiped out all three heaters! But in my backtracking and repairing where the shorts were occuring (dirty and shorting trimmer cap and lack of insulation for the base), I used the valves to still test the circuit before putting new functioning ones in that may blow again.
It occurred to me that it's only the heaters that blew, so while non functioning and trash, the rest of the internals will still at least connect to the right places, enabling me to check voltages to an extent. Though one doesn't want to be buried in valves. It also seems sad to throw away something in limited supply, but then if it's broken... What can one do? |
2nd Jul 2022, 11:36 am | #26 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Faulty valves - Scrap or keep?
Sadly Spencer,
once the heater or filament is blown the valve does not function, no emissions, so no meaningful measurements can be had by using it... Alan
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2nd Jul 2022, 12:13 pm | #27 |
Hexode
Join Date: Apr 2011
Location: Grove Park, SE London
Posts: 382
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Re: Faulty valves - Scrap or keep?
Oh yes, I know the current would be all wrong and actual measurements are off but I mean in the sense that I was able to check in practice that no sparks or shorts were occuring at least in those conditions, which make me comfortable enough to put new valves in. A bit like when you fit stabilisers to a bicycle!
Perhaps it's not a good method. My next project also involves 2x DF91s, so I may keep the dead DF91s I have for that purpose. |
2nd Jul 2022, 2:54 pm | #28 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 898
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Re: Faulty valves - Scrap or keep?
There can be shades of grey when it comes to some valves being 'faulty'.
One such example is the 6BM8, which I'd suggest is the most 'pulled' noval power pentode in Australia - in that anyone involved with servicing valve equipment would likely have pulled them, given the variety of radio's and radiograms etc that this valve was used in. A few years ago I won a box of 83 such pulled valves for I recall $2. As an exercise in frugality I tested each one in a typical cathode biased test circuit for nominal anode voltages, and for grid leakage of the triode as well as the pentode, and then tested good like valves for matched pairs in a PA amp. I ended up with 17 matched pairs, and an additional 34 ok pentodes (the triode grid was leaky). I didn't test the 'ok pentodes' to see how many could be used as matched pairs, but likely to be a few. Based on that batch, my general comment would be that in Australia there are likely quite a few 'faulty' valves that could happily live a useful life. Furthermore, one option is to use just the pentode portion of the 6BM8 if it is still ok, especially when the valve has been pulled due to a leaky triode input grid. Obviously not for existing applications that actually need a 6BM8, but certainly ok for those just wanting a noval power pentode (with probably more than a 7W anode dissipation limit now). |
2nd Jul 2022, 2:59 pm | #29 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: Faulty valves - Scrap or keep?
I don't keep old, duff valves in large numbers, but I do hang on to a couple, for example a low emission SD4 in the hope that one day it is possible to revive it. I don't hold much hope mind, but the couple that I keep don't take up any room. Not just that, but one day I may acquire a set that uses (say) an SD4 and I can fit it if only for the visual aspect in a 'vision' only radio.
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A digital radio is the latest thing, but a vintage wireless is forever.. |
3rd Jul 2022, 9:53 am | #30 |
Hexode
Join Date: Jun 2003
Location: Burntwood, Staffordshire, UK or Kabaty in Warsaw Poland.
Posts: 438
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Re: Faulty valves - Scrap or keep?
I bet most of the valves I have aquired over the years, stored in boxes here and there are probably dud.
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3rd Jul 2022, 10:03 am | #31 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: Faulty valves - Scrap or keep?
You're welcome to use my Mullard valve tester Mark!
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A digital radio is the latest thing, but a vintage wireless is forever.. |
3rd Jul 2022, 10:10 am | #32 |
Hexode
Join Date: Jun 2003
Location: Burntwood, Staffordshire, UK or Kabaty in Warsaw Poland.
Posts: 438
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Re: Faulty valves - Scrap or keep?
Thanks Steve, must bring those PX4s over one day !
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3rd Jul 2022, 6:18 pm | #33 | |
Heptode
Join Date: Jan 2008
Location: Shrewsbury, Shropshire, UK.
Posts: 825
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Re: Faulty valves - Scrap or keep?
Quote:
David. |
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3rd Jul 2022, 6:50 pm | #34 |
Octode
Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,910
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Re: Faulty valves - Scrap or keep?
I have a few dud valves which I keep for messing around with on a rainy day. I made a couple of those valve component displays that Mullard made with the grids, cathode ECT. carefully glued to a back board.
I have a NOS EABC80 which the pip got broken off after an unlucky accident I intend to do the same with sometime I did a nasty experiment to an EF80 that was a well baked pull from an old telly just to see what a small signal valve could take. With the heater lit correctly I connected a big high voltage power supply between anode and cathode without any current limiting I think I got nearly 500mA at over 400 volts before the cathode strip parted from the cathode. Just before it expired the anode was glowing bright yellow!! Christopher Capener
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4th Jul 2022, 7:23 pm | #35 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: Faulty valves - Scrap or keep?
I made a duff VU111 valve into a clock for someone who had worked in radar.......he loved it!
Cheers.... Simon.
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The honesty of imperfection.......... |
4th Jul 2022, 8:13 pm | #36 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: Faulty valves - Scrap or keep?
That is amazing!
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A digital radio is the latest thing, but a vintage wireless is forever.. |
4th Jul 2022, 8:45 pm | #37 |
Pentode
Join Date: Feb 2022
Location: Dalbeattie, Dumfries and Galloway, Scotland, UK.
Posts: 116
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Re: Faulty valves - Scrap or keep?
Interesting thread. I am actually doing a big sort out of valves acquired over the years.
Some are definitely NOS (unless somebody has gone to the extent of preparing a factory level tissue paper wrap and tuck job) but many are an unknown and will lie in wait until I actually need to find out if they are good or not. Known duff are mainly 're-atmosphered' and the internal workings studied. Sometimes just get put in the glass/metal household waste bin (it's all eminently recyclable). But never packed away back into the carton to disappoint somebody in another half-century's time. Which got me thinking... Has anybody ever come across valve boxes where the engineer had helpfully filled out the printed table "Customer..... Model..... Date removed...."., etc ? Did you, as a service guy, actually fill out that table ?? |
5th Jul 2022, 6:35 am | #38 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
Posts: 986
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Re: Faulty valves - Scrap or keep?
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The honesty of imperfection.......... |
6th Jul 2022, 6:10 pm | #39 | |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: Faulty valves - Scrap or keep?
Quote:
They invariably came back with a report saying "these are still within original production tolerance" which was reassuring.
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9th Jul 2022, 7:55 am | #40 |
Heptode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 663
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Re: Faulty valves - Scrap or keep?
I have a substantial box of "dead" valves/tubes. Mainly the large base 4,5,6,& 7 pin tubes.
It has proven a godsend when having to build extension cables to work on radios, etc. not to mention helping out my ham buddies. I also use them as bases for HB coil forms. Typically, I toss the wire pin tubes that are bad and the octals that are missing any base pins. I tossed literally 4 35 gallon garbage cans of bad tubes out (I sold tubes at Hamfairs and would only sell tested, good ones) a few decades back. My trash man was not happy with me either, because of the weight. Anymore, I toss any tube unless it has the odd shape to make Steampunk stuff with. I had a local artist and gifted him with several shopping bags of "duds" to make Steampunk stuff with. He did a good business selling them on Etsy a few years back. |