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Dynaco Amp

170.115.248.24
Posted on March 16, 2020 at 07:53:10
john.lynch@phila.gov
Audiophile

Posts: 9
Location: Pennsylvania
Joined: February 10, 2020
 I had a tube flash in one of my power tubes in, I replace all 4 power tubes and cleaned up the chassis and and tube sockets. Amp powers up ok, After awhile there is a slight hum in the left channel and the second power tube on the left channel is glowing a lot more then the other power tubes. Please advise ?
J.LYNCH

 

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How do your voltages check against what the manual lists? (nt), posted on March 19, 2020 at 06:16:42
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007

 

RE: How do your voltages check against what the manual lists? (nt), posted on March 19, 2020 at 06:33:05
john.lynch@phila.gov
Audiophile

Posts: 9
Location: Pennsylvania
Joined: February 10, 2020
 Did not check that yet, I will take my meter home this weekend and check. I should have plenty of time to do this. I did all that you told me to do before. After cleaning up unit and pin connectors for tubes, I switched the left side power tubes with the right side. When I powered it up after that, the tube that was flashing internally started to flash immediately. So I replaced all power tubes. After I check the voltages, I will get back in touch you. Thank you again, for all of your help.
J.LYNCH

 

Is the problem tube in the same socket which gave you trouble the last time?, posted on March 20, 2020 at 05:48:29
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007
 If so, that should be an indicator that there likely may be an issue with the socket itself. If not, we'll try and help you troubleshoot from there.

Did you buy your tubes from Jim? If so, you may want to email him and ask his advice. He's a wealth of information, and always seems willing to help, especially his customers.



 

RE: Is the problem tube in the same socket which gave you trouble the last time?, posted on March 20, 2020 at 06:07:45
john.lynch@phila.gov
Audiophile

Posts: 9
Location: Pennsylvania
Joined: February 10, 2020
 No, it is not. When I switched tubes like you told me to do, As soon as I powered up the unit the tube in question immediately started to flash internally, When that tube was in the other socket it would start to flash when I turned up the volume about half way
J.LYNCH

 

I meant with the new tubes, posted on March 20, 2020 at 09:00:27
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007
 Just brainstorming.

Meanwhile, you might want to take a look at the article linked below, written by Dave Gillespie. He offers a variety of solutions, but the easiest, and least expensive one makes the most sense to me, which is to do the following:

Add a 100 ohm resistor between each pin #4 of the output tubes and the green (screen) wires on your output transformers. The article linked below will explain the "why" of it, but $2 for four resistors is a LOT cheaper than an output tube.

Good luck with it!







 

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