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 |
Re: EBC33 valve
You do find these manufacturing faults occasionally.
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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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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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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. |
Re: EBC33 valve
1 Attachment(s)
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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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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Re: EBC33 valve
Pic 1 looks like it was never soldered.
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