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Burned out EMM 801

scuba

scuba

My idea of spin class.
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I just purchased a Dynaco FM3 from FleeBay. Great tuner and works fine, but the EMM 801 double cat's eye arrived burned out. Contacted the seller right away and he is sending a replacement, so no problem there. The question I have relates to the cause of the failure. I have never seen a tube burn out this way. Actually, I have never seen a burned out cat's eye either. I have attached some pics of the tube and was wondering if anyone could let me know if this kind of failure could be due to a problem with the set itself or is it common to these kind of tubes. I have ordered two NOS\NIB Telefunken tubes from Hong Kong for the princely sum of $150, and before blowing these ones up, would like to know if it is safe to put one of them in.
 

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The black spot is metal cooked off the cathode - old eye tubes like this usually have black spots there... just like old 6SN7s have spots on top over the cathodes. Just looks worn out to me...
 
Good for you on getting super high quality tubes for that as it also serves as the alignment meter. I't very important to have a good eye tube in before attempting the alignment which is very easy.
 
It's possible to replace the rare and expensive EMM-801 dual tuning eye with the much cheaper and more common EM-84, though the change requires rewiring of the tuning eye tube socket. The tuner won't have a Stereo lamp after this change, but at least it will still be usable. I have the instructions somewhere in my Dynaco files.
 
jaymanaa said:
Good for you on getting super high quality tubes for that as it also serves as the alignment meter. I't very important to have a good eye tube in before attempting the alignment which is very easy.
Click to expand...

I read the alignment instructions, looked like a pain in the ass to do.
 
Yeah, I have contemplated actually going through the alignment instructions for a FM-3. I just get the feeling the payoff wouldn't match the effort.

No offense to any FM-3 owners. I own one myself. Just think it's one of Dynaco's weaker products.

Good to know a vintage EMM-801 is worth at least $75.
 
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