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kuliko
Joined: Sep 03, 2006 Posts: 10 Location: Europe
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Posted: Sun Sep 03, 2006 4:56 pm Post subject:
Problem with TM-5 |
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Hi everybody,
I've recently purchased a second-hand TM-5. It has some weird issue: If I place it in HORIZONTAL position on the floor (the way it's intended to), the unit turns off 1-2 minutes after it's been turned on!! That is, not only it stops producing any sound but even all the tubes and pilot light turn off. Then I have to wait some seconds before the unit works again (for only a couple of minutes though...). However, I have tried placing the unit on one of its sides, bottom lid removed, and the unit works flawlessly for hours!! ...The same occurs when I remove the 6BN6 (This tube is not in the primary signal path so the preamp works, without the "brutal overdrive" option this tube provides though).
I suspect the problem has to do with heat: Perhaps a cold solder joint? or maybe the TM-5 has some sort of thermal fuse that switches the unit off in case of excessive heat?
Any hint? |
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metasonix
Joined: Dec 28, 2003 Posts: 34 Location: CALIFORNIA
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Posted: Sat Sep 09, 2006 6:59 pm Post subject:
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Yes, it has a thermal fuse. Yes, it is overheating inside. I can put a larger fuse in the unit if you wish. (Or you could move the thermal fuse away from anything that gets hot, such as rectifier diodes. It is the dark yellow chiclet-like device mounted on the PC board near the red pilot lamp.) |
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kuliko
Joined: Sep 03, 2006 Posts: 10 Location: Europe
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Posted: Sun Sep 10, 2006 3:56 am Post subject:
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Thanks a lot. If you give me the ratings of this thermal fuse I could buy a larger one and replace it myself. I live in Europe so sending the unit to the US and back can be very expensive.
Thanks in advance. |
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metasonix
Joined: Dec 28, 2003 Posts: 34 Location: CALIFORNIA
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Posted: Wed Sep 13, 2006 12:43 pm Post subject:
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Okay, it is a Raychem RUE160 "polyfuse". Replace it with the next size up, which would be a Raychem RUE185 or similar.
And MAKE THE LEADS AS LONG AS POSSIBLE. Keep the fuse's body away from components on the PC board that run hot.
Once you do that it will run the 6BN6 tube with no problems (in fact, it will also use a 3BN6 or 4BN6, which draw more current). |
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kuliko
Joined: Sep 03, 2006 Posts: 10 Location: Europe
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Posted: Thu Sep 14, 2006 11:46 pm Post subject:
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Thanks for your advice. I'll try that asap. |
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kuliko
Joined: Sep 03, 2006 Posts: 10 Location: Europe
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Posted: Sat Sep 23, 2006 8:51 am Post subject:
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Hi,
I couldn't find a Raychem Polyswitch RUE185 so I tried a RUE250. I followed your advice about leaving the leads as long as possible and everything went OK.
Thanks indeed |
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