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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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16th May 2018, 11:57 pm | #1 |
Hexode
Join Date: Oct 2007
Location: Ossett, West Yorkshire, UK.
Posts: 406
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EBC33 valve
Hi folks,
While in the process of refurbishing my Bush DAC90 I collected some valves to try out. Not having a working valve tester I thought I'd just do a quick heater continuity test on each of the valves. They all checked out okay except for an EBC33 which was open circuit, or so it appeared! On closer inspection I noticed there was no solder on the bottom of the valve pins. Pushing my multi-meter probes into the ends of the heater pins, to touch visible wires, gave me a continuity reading! Is it possible that Mullard just forgot to solder the pins? All of the other valves I collected together for the set have soldered pins! Regards, David |
17th May 2018, 12:06 am | #2 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,947
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Re: EBC33 valve
You do find these manufacturing faults occasionally.
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17th May 2018, 6:40 am | #3 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: EBC33 valve
I always try resoldering the pins if I find an O/C heater. Some valves with a high current heater regularly have gone O/C and come back to life with a soldering iron.
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17th May 2018, 4:28 pm | #4 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,396
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Re: EBC33 valve
It's not uncommon with IO and similar base valves- the leadout wires may have been heated and therefore a little tarnished during the bulb processing and sealing, and the soldering at the end of the hollow pins may have been both cursory and minimalist. I've often found dry-looking joints with just a tiny amount of solder in the end of the hollow pin, and that rectifiers with their high current heaters seem particularly prone to joint iffiness.
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17th May 2018, 11:06 pm | #5 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: EBC33 valve
Quote:
The same soldering defects can also occur on plate and grid top caps. One radio I owned with a 6k7 in the IF had an intermittent grid connection here, it took weeks to find what the cause of the trouble was the very first time I encountered it. |
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19th May 2018, 6:53 pm | #6 |
Hexode
Join Date: Oct 2007
Location: Ossett, West Yorkshire, UK.
Posts: 406
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Re: EBC33 valve
Well I've cleaned and soldered the ends of the pins and now have a fully functional EBC33 again working happily in my Bush DAC90. I couldn't see any evidence of previous soldering. Hopefully I've attached a photo of the pins of both my EBC33s to this post so you can see what I mean.
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19th May 2018, 8:05 pm | #7 |
Octode
Join Date: Jan 2007
Location: Dorridge, West Midlands, UK.
Posts: 1,483
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Re: EBC33 valve
Pity they don't include the day of the week in the batch code it would probably show as produced on a Friday!!
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19th May 2018, 8:49 pm | #8 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,932
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Re: EBC33 valve
Pic 1 looks like it was never soldered.
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