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152.11.92.45
I have a quick question, and I apologize in advance if this is stupid, but I won't know if I don't ask...
I have a new Dennis Had Inspire preamp that uses a pair of 01A tubes. As this tube type hasn't been made in many, many years, the tubes I've been able to locate have very heavily tarnished/dirty pins. In an effort to clean the brass pins on one of my tubes to ensure good contact with the tube socket, I applied a little bit of Brasso with a Q-tip to each pin and rubbed gently to distribute the polish. I then used a felt polishing tip on my Dremel tool and gently polished each pin to a beautiful shine. Upon re-inserting the tubes into my preamp, one works fine, but the other does not "fire" on power-up. Is there any way polishing the pins in the manner I employed could "kill" a tube? Is there a better and safer way to get the tube pins nice and clean to ensure good contact? I read somewhere that a Magic Eraser works well, but that requires water, and I don't know if that something you want around the base of a tube. Any thoughts/advice would be greatly appreciated.
Thanks so much,
Chris
Follow Ups:
I use a maple shade cleaning kit which works great
Thanks; I'll give this a try!
Cleans better than anything else I've found.
I've used those before with great success. They wore down faster than I'd like, but did a very nice job. I now use a Dremel with one of their funky attachments.
Your interest may vary but the results will be same. (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Why don't catfish have kittens? (Moe Howard 1937)
Edits: 11/02/23
Thanks, Andy; this is a great idea1
I use maple shade tube cleaning kit. comes with foam and contact enhancers. I am not sure tube is bad do you have a tube tester? I also use dental tools to tight sockets insertion point. My other suggestion only really old had to find tubes I let them sit in alcohol for w a week at or 90 percent or higher-grade alcohol. Then after they dry use caig or some other contact enhancer which in my experience does work but not magical or snake oil.
I have been using a 01A/201/301 preamp for years now.
My experienced when having pin contact issues was always having poor contact with the socket due to dirty pins (they are 100+ years old tubes after all). Have you tried switching the tubes and see if the filament for the one in suspect glows?
If you have a spare socket and test wires with alligator clips, or you can connect the wires directly to pins 1 & 4, you can simulate the operation ensuring good contact for the heaters using four (3) 1.5 Volts AA battery. You can easily see the filament glow if the filament is healthy.
It is easy to buy a 01A replacement tube, but to get one that is quiet (let alone a pair) is a challenge sometimes.
My experienced is that measuring pins 1 and 4 (filament) gives you about 0.2 ohms.
I bought about 24 01A/201/301 tubes before I found three quiet pairs (Radiotron, Cunningham, and Ceco) for my preamp. I always buy NOS from a dealer and avoid Ebay.
Goodluck!
Hi amandarae,
Thanks so much for your helpful response!
If you don't mind sharing, could you recommend dealers who sell quiet 01A tubes. You are right about eBay; the tube that just died upon cleaning was from an eBay seller...
Thanks so much,
Chris
I bought my tubes from Mr. Jim Cross at Vacuumtubesinc.com
Awesome; thanks! I'd not come across his shop before.
Best,
Chris
First, have you measured the resistance across the heaters with a multimeter?
Second, it's clutching at straws but if the heaters are open circuit you could try re-soldering the heater pins by holding a soldering iron on the ends of them and feeding in a bit of fresh solder if that's possible.
Hi Andy,
Thanks for your help. The 01A tube has 4 pins - 2 are thick and plug into the front socket holes, and 2 are thin and plug into the rear holes of the socket. Do you happen to know which ones go to the heaters?
Thanks again,
Chris
you can measure across them.
iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.
Thanks, John,
So, if I measure across the two thick pins, I get a reading of "over limit", even if I set the scale on my multimeter to 2 MOhm, so I am assuming this means the heater circuit is intact?
best,
Chris
Either you have poor contact between the probes of your DMM and the tube pins or you (unfortunately!) have open heater circuits in the tubes themselves.
If you put both probes on the SAME tube pin you should get readings of zero or very near zero resistance. If you are still getting high resistance readings like you have now, it means your probes - one or both - aren't making good contact with the tube pins. Try this on both of the fat pins so you know you can make good contact on both of them.
Please post your results.
Hi Jim,
Putting both probes on the same pin gives me readings of essentially zero, so I guess that means the heater circuit in the tube is bad :-(
Thanks so much for your help confirming this,
Chris
Yes, it seems the tubes themselves are at fault, sorry to say.
I'm glad I could help - but I sure wish you would have had a better outcome!
Or does this mean it is broken and I should try Andy's idea of reflowing solder?
.
Your interest may vary but the results will be same. (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Why don't catfish have kittens? (Moe Howard 1937)
Give it a little jiggle next to your ear. Anything bouncing around inside?
Your interest may vary but the results will be same. (Byrd 2020)
I can't compete with the dead. (Buck W. 2010)
Cowards can't be heroes. (Byrd 2017)
Why don't catfish have kittens? (Moe Howard 1937)
Hi Byrd69,
I tried that when it wouldn't fire, and all is silent, so it doesn't seem anything has broken loose inside.
Chris
This might also be a dumb question, but did that tube ever work? Is it possible you're beating a horse that was already dead?
If glass were cracked, or if air had got inside, I'd expect the getter to go off and turn white.
Hi Sondek,
Yes; the tube was working perfectly, but I thought cleaning it would be a good idea... It seems it was not :-(
The getter did not go off and nothing turned white on power-up; the tube just never did anything. Does this suggest the glass is okay?
Thanks,
Chris
It would seem that the envelope is intact.
I'd be looking at the physical connection of pins and socket.
It is possible the cleaning caused a fracture in the heater element. Vibrations from the Dremel? I know nothing about this particular tube, so take with grain of salt.
There are a few placed where the process could yield the results you have experienced-
While the Brasso may well be conductive, the oxide on the pins is not a great conductor-
Try wiping with IPA (Isopropal Alcohol)
You may also need to tighten the socket clips-
There are posts around here that explain this process
Lastly, is it always possible that working on the pins may crack the glass and upon power up cause a failure-
I am not that familiar w/ the 0A1 so I can't help on testing, but if one works, while the other does not, switch positions and see if the "bad " tube is still 'Bad'...
Happy Listening
Hi 6bq5,
Thank you for your response. I did, indeed, thoroughly clean the tube pins and tube base with IPA and allowed them to dry prior to reinsertion; I should have mentioned that.
I am sure the tube socket clips are good and tight, because the preamp is only a month old and it actually requires a fair amount of effort to insert the tubes.
As far as cracking the glass (or maybe loosening a connection inside the tube) as a result of handling the pins and the vibration from the Dremel tool, those were my concerns with my observations.
I did not, in fact, try swapping the "bad" tube to the other socket, which is a great suggestion that I will try. However, when I inserted a spare 01A tube I had on-hand into that socket, it immediately fired up and the preamp works perfectly, so I am sure the socket is good, and I fear my zeal to have nice shiny pins has likely killed a perfectly good tube.
Is there a safe method for getting tube pins nice and clean without causing damage?
Thanks again,
Chris
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