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Topic: Tubefex Problem |
Richard Tipple
From:
Ohio, USA
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Posted 13 Apr 2004 6:22 pm |
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Can one or both 12ax7 tubes be bad and still light up .
When ever I use the Tube in a chain ,,there is no sound at all. Everything else works fine when not using the tube mode, volume and all. I pulled the cover & checked the tubes to see if there was any glow,,and both tubes light up,,but no sound when in the tube mode,,,battery looks good ,,no leakage.
Anyone ever encounter this |
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Don Henry, Jr
From:
Newberry, South Carolina, USA
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Posted 13 Apr 2004 7:47 pm
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Yes, a tube can definitely be totally defective, or weak, and still light up. In fact this is most often the case with tubes. |
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Ken Fox
From:
Nashville GA USA
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Posted 13 Apr 2004 7:59 pm
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I would swap the tubes around and try again. The clean mode uses one tube only, maybe one is bad. Is this a recent problem?
Also there is a motorpot in the units that can cause problems. It may have lost it's ground (early models depends on the screws that mount the motor pot to the circuit board for ground). Later models have a strap of wire from the frame of the motorpot to a ground solder pad on the circuit board. I recently changed a battery in a Tubefex and found these screws had loosened up from vibration! Here is a link to the Tuibefex site with more info on the motorpot "care and feeding". There is also some mods for the pot shown there.
http://tubefex.home.comcast.net/
If a tube does not fix it and you are not an electronics person, then send it to Peavey! They offer the best service for these units.
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Mike Brown
From:
Meridian, Mississippi USA
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Posted 14 Apr 2004 5:09 am
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You might want to check the .25/250 volt fuse as it can cause these symptoms if it is open. The original fuse was a 3/16A, but we changed it as this fuse is now unavailable.
Mike Brown
Peavey Electronics Corporation |
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Richard Tipple
From:
Ohio, USA
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Posted 14 Apr 2004 9:27 am
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Thanks fellas
Ken I went to the site you linked to and I soldered the a ground wire the way they said.
I get a little sound when running the lead and ultra mode of tube. I dont know if I had any sound there before as I only checked these modes out just a little while ago. Still nothing after switching the tubes around though in the clean mode.
Do anyone know where I can pick up a pair of 12ax7 s if new tubes dont do the trick it looks like Dr Peavey may need to look at it.
Mike ,where exactly are the fuses located you were refering to. I checked the small glass ones I saw (2) of them. Are there more I should check out.
One last question,,do I need to remove the whole chassis to tighten the screws you were refering to Ken ?
Whew!!! |
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Mike Brown
From:
Meridian, Mississippi USA
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Posted 14 Apr 2004 10:12 am
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| They are located to the left of the transformer. Hope that this helps you out. |
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Richard Tipple
From:
Ohio, USA
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Posted 14 Apr 2004 12:10 pm
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Thanks Mike
They checked out ok 
Im going to replace the tubes & see what happens
If that dosent do it ,I will be in touch to get it to Peavey for a re-hab
Thanks again |
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Ken Fox
From:
Nashville GA USA
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Posted 14 Apr 2004 3:36 pm
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Richard, take a look under the motorpot and watch to see if the piece hanging down (the pot slider) is moving in response to the pregain control! I just got in a near new (version 2.0) unit from another Forum member that I am removing the battery and replacing the memory chip with the Tim Batts memory chip. The pot is sticking on his unit. Even after spraying it with a lubricated contact cleaner it still grabs and grunts!
Yes, you have to remove the top, bottom, the transformer screws and remove the screws and nuts that are used on component heat sinks (on the side). You end up with a chassis with a front and rear panel and a transformer hanging loose! Even to change a battery this is has to be done.
Reading on another forum for Tubefex I found that a Deoxit cleaner is commonly used. I tried it, the pot has started to free up and move. It is still sluggish, but works somewhat. Sometimes when you turn it to "0" it does not get there. Spinning it again it tends to make it to the off position. I am going to let it sit overnight and see if it gets any better. [This message was edited by Ken Fox on 14 April 2004 at 07:35 PM.] [This message was edited by Ken Fox on 14 April 2004 at 07:38 PM.] |
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Ken Fox
From:
Nashville GA USA
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Posted 15 Apr 2004 4:53 pm
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| Well, I pulled it off the circuit board and gave it another shot of Caig Deoxit D5. It is up and running well now. I will test it further tonite and tomorrow, so far so good! |
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Richard Tipple
From:
Ohio, USA
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Posted 17 Apr 2004 1:01 pm
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Just wanted to let you all know the Tubefex is up & working great now
Thanks to Ken
I checked the little doo---dad under the motor port & sure enough,,it was stuck.
I lubed it with some electrical spray lube
and it works smoothly now.
Heck,, I didnt even know it was under there till Ken mentioned for me to check it.
So thanks to all & especially to Ken Fox |
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