I need help with my MA-240 - Dan - OTL Asylum

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OTL, Output Transformerless Amplifier User Group.

I need help with my MA-240

0

A week ago I blew a fuse for one of my 6C33 output tubes. I replaced the tube and its compliment tube with a matched pair. I let them burn in stand-by for 6 hours. Then rebiased and let them sit for about 15 minutes in full power before I noticed that the plate of the tube in the position that the fuse blew was red hot. I thought I had another bad tube. But when I replaced it the same thing happened. I have found past discussions on this. One described checking the grid resistor for damage or open. It is fine and reads 98 Ohms. I can see no damage at all to it or surrounding circuitry. So I replaced the tubes again and its still the same. I even tried it with the speaker disconnected fearing that I may have damaged it. But that didn't make a difference either. I also noticed that I do not have a plate resistor in my amps. I have read discussions on that also and I am wondering if I should install them.
Please help if you have any suggestions at all. I'm going thru severe withdrawl here.

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Topic - I need help with my MA-240 - Dan 16:58:01 09/19/04 (12)

Re: I need help with my MA-240 - Lew 07:10:49 09/20/04 (11)

Re: I need help with my MA-240 - mark 10:19:16 09/20/04 (10)

grid resistor vs grid-stopper - Lew 10:54:29 09/20/04 (9)

Re: grid resistor vs grid-stopper - Dan 17:16:40 09/20/04 (8)

Re: grid resistor vs grid-stopper - Lew 07:19:00 09/21/04 (0)

Re: grid resistor vs grid-stopper - mark 19:20:18 09/20/04 (6)

Re: grid resistor vs grid-stopper - Dan 18:30:26 09/21/04 (5)

Re: grid resistor vs grid-stopper - mark 06:37:51 09/22/04 (4)

Re: grid resistor vs grid-stopper - Dan 07:11:24 09/22/04 (3)

Re: grid resistor vs grid-stopper - Lew 07:18:35 09/23/04 (0)

Re: grid resistor vs grid-stopper - mark 07:25:34 09/22/04 (1)

Conclusion - Dan 16:18:02 10/03/04 (0)

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