First time experience of a tube having a dry joint - an old radio valve where the heater had stopped working. Seller suggested re-soldering the pins and indeed that restored continuity. I've never had this problem before. Now I know.
How common is this, and have you experienced similar issues?
How common is this, and have you experienced similar issues?
Hello,
Bad solder connections are often caused by not enough heat to let the solder flow well and using poor quality solder that doesn't have good flux to help it flow.
There are lots of instructions and videos on the web showing how to solder, consider taking a look around.
Regards,
Greg
Bad solder connections are often caused by not enough heat to let the solder flow well and using poor quality solder that doesn't have good flux to help it flow.
There are lots of instructions and videos on the web showing how to solder, consider taking a look around.
Regards,
Greg
Mostly the russian (after soviet era) tubes produces the same anomalies.
I also have EH 300B tube, where this intervention was necessary.
Poor SQ ... or the day before there was more vodka than needed. 😛pp
I made a loctal to octal adaptor, and had this problem. I presume there is a technique for soldering wires in valve base pins since it did not feel like an exact science when I was doing it. Is the answer flux? If so, any preferred product?
The annoying thing was the heater tested fine with the tube+adaptor out of the socket, but the force of pushing the tube+adaptor into the socket opened the poor joint, so the heater would not work, making me dismantle my tube tester on the chase for a heater issue :-(
The annoying thing was the heater tested fine with the tube+adaptor out of the socket, but the force of pushing the tube+adaptor into the socket opened the poor joint, so the heater would not work, making me dismantle my tube tester on the chase for a heater issue :-(
As someone who repaired old tubes radios from the 20,s onward the soldered connection joining the pins and the wire coming from the tube elements had to be resoldered in many cases due to------- yes-----old age deterioration of the actual solder chemical structure .
Please check out the flux used in those days of long ago -aka "old school " .
Please check out the flux used in those days of long ago -aka "old school " .
I saved an EL34 in my amplifier re-soldering a filament pin. Tube came back to life and is still going fine.
They are the hottest ones after all, passing the most current.
No wonder they suffer first.
Because of the heat the tube produces the joint will expand and when it cools of the different metals with their different temperature coeffients will crimp again. Over the years this will cause little cracks and because of this mini sparks will appear over these cracks causing a higher resistance and a higher resistance means more heat production when a current is flowing (relativily high on heaters)... you get the point ..
If you add a bit of solder when reflowing an Octal base pin, be sure to use 63/37 Sn/Pb eutectic alloy. As was previously mentioned, Brand "X" is a poor choice. Stick to proven performers, like Kester and MultiCore.
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I've got 3 100THs without filament continuity and no visual signs of a broken filament. I might give this a shot in the off-chance it works.
One of them didn't light up, then it lit up another time I inserted in the test jig, then next time it wouldn't light again. I've got my fingers crossed...
One of them didn't light up, then it lit up another time I inserted in the test jig, then next time it wouldn't light again. I've got my fingers crossed...
Folks who play around with those "three-legged fuses" mounted on circuit boards see something similar a lot with TO-220 voltage regulators and audio driver transistors. Heating and cooling cycles form circular ring cracks in the solder, eventually opening the connection. Good practice is to resolder *all* of them with 63/37.
YOS,
Chris
YOS,
Chris
maybe. I have had 2/3 KT8C with identical problems.
I think in that case it's because the ceramic base expands a lot and tears the wires out.
I managed to get 2 back to life totally renewing solder and extending the wires back into the pins, then exhaust paste to resettle the glass back in the base.
The 3rd just required reflowing lots of solder into heater pins.
In view of the cheap KT66 syndrome I was happy to get them back to life, as they are 70yrs old anyhow and one was NOS.
I use old SOVIET solder I get in skeins from the local shop.
superior to anything modern especially that awful chinese rubbish!!!
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a 150 watt solder pot is good to use....https://shopee.ph/-CHIWANJI1-YD-11C...ring-Bath-220V-100-580-i.140620954.7378436137
Tony, do you know if a 120 VAC version of that solder pot is available, for those of us located in North America?