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Old 11th January 2011, 01:25 AM   #11
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I think that assuming it is a class AB amp then the one that is still glowing is bad and the one that is not is good. That might not always be the case but I have seen it several different times.
This is a single ended amp which by definition is class A. It is the heater that quits glowing, so if it is the tube the dark one is the bad one. No light is bad.

If the problem follows the tube, it looks like a bad tube. There are two possiblities, there is an internal defect that causes the heater to go open when it gets hot. I have seen this only once and it was a Sovtek tube (same factory as EH). The more likely possibility is that the soldering inside the pins of the tube itself has grown intermittent. As suggested this can sometimes be fixed by reheating the pins on the base of the tube with a hot soldering iron and applying a small amount of solder to the very tip of the pin. I have seen this happen with tubes from every vendor and the repair is not always succesful.

Yes, the Simple SE can run fine with only one tube.
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Old 11th January 2011, 02:23 AM   #12
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Originally Posted by tubelab.com View Post
As suggested this can sometimes be fixed by reheating the pins on the base of the tube with a hot soldering iron and applying a small amount of solder to the very tip of the pin.
Hi,
What is the likeliness that I screw it more by heating the pins (2 and 7)? Like a 4:1 ratio to blow up the entire amp because the tube is now really bad.

Thanks,
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Old 11th January 2011, 05:13 AM   #13
rmyauck is offline rmyauck  Canada
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It's worth a try as there's nothing you can short out in your amp, or hurt by trying to resolder pins. The heater isn't connected to anything that could cause a short. If the tube was dropped that would be a different story as something could be shorted out inside it.

Could this type of problem be caused by bad contact in socket to tube pins causing pins to overheat? Afterall there is a fair amount of amperage on big power tube heaters.

It still could be a bad tube filament, as they are fragile from heating and cooling many times.


Are you using an 5AR4/GZ34 rectifier tube or some other one like a 5U4?
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Old 11th January 2011, 11:40 AM   #14
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Are you using an 5AR4/GZ34 rectifier tube or some other one like a 5U4?
Hi,
I am using a 5ar4. No solid state rectifier present.

Best regards,
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Old 11th January 2011, 01:37 PM   #15
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What is the likeliness that I screw it more by heating the pins (2 and 7)? Like a 4:1 ratio to blow up the entire amp because the tube is now really bad.
Damage is unlikely unless you leave enough solder on the tube pins that they are too big to fit the socket, then you make it fit the socket, then break the tube trying to get it out, cut your hand on the broken tube, then try to pry the tube out breaking one pin off in the socket, and break the socket trying to get the pin out. Yes the odds of this happening are low, but I know that it has happened at least once!

Scrape the excess solder off the pins with an X-acto knife after soldering.

All octal tube pins are supposed to be the same size. They are not. Some JJ's are too small causing intermittent connections. Some of the Chinese tubes are a bit big. The contacts in the socket could be slightly loose leading to an intermittent connection. The pins could also be dirty or slightly oxidized. A light scraping or sanding could help.
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Old 12th January 2011, 10:16 PM   #16
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Oh so SE means single ended? I get it now.
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Old 14th January 2011, 02:06 AM   #17
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Thanks for the re-soldering solution. It worked for a few days, but the problem is now back (bad tube: filament between pin 2 and 7).

I was looking around and they pretty much sell those only in pairs. I have an Electro-Hamonix. Where can I buy a single one? Is it a good idea to buy a single one and have tubes of different age running on the amp?

Any suggestion on how to replace the tube(s). Let say I am willing to spend 50$ ish.

Remember I have a SimpleSE with GXSE output transormer from Edcor.
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Old 14th January 2011, 02:37 AM   #18
rknize is online now rknize  United States
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For a single-ended amp, it doesn't really matter. Personally, I'd just get the pair. Alternately, you can look on eBay. AES also will sell singles:

http://www.tubesandmore.com/cemirror...EL34-EH-TH.GIF
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Old 14th January 2011, 08:41 AM   #19
Ian444 is offline Ian444  Australia
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I agree, just whack a couple of new tubes in it and be done with it. Check the bias on fitment of new tubes. Keep the good one as a spare for future troubleshooting if required.

This guy is very good to deal with IME, when I need to know that the tubes will work and are well-tested so that I only spend the money ONCE instead of twice. $31.50 for 2 x EH EL34 http://pages.prodigy.net/jimmcshane/tubes.htm

Last edited by Ian444; 14th January 2011 at 08:55 AM. Reason: Added somewhere to get tubes from
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Old 14th January 2011, 10:29 PM   #20
rmyauck is offline rmyauck  Canada
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I second Jim for tubes. He may have an crooked or slightly tilted one to sell too as he lists those for less $ at $13.50 if he has any. Near top of listings. EH 6CA7 might be considered too. Some like sonics better.

He also sells those Russian 6N3C-E or 6P3C-E which might be worth trying, @ $29.50 a pair. They are a military grade tube and should last! Well liked by many for sonics.
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