My current 5E3 Tweed Deluxe build has had major overheating issues since I first assembled it. (Mojotone Kit). And I have a couple of questions for anyone more knowledgeable on the amplifier than I.
I first thought to check the bias of the amp, thinking this was the prime cause of the overheating, I did the calculations and I got 41mA on the output tubes each. This is almost 120% dissapation. This seems like a major issue. However I dont know how to correct this. I have the standard 270 Ohm bias resistor, I figured that if I replaced it with a 330 Ohm resistor this would put me back down to about 96% which sounds about right for a Deluxe.
I've read on some forums where people say that you don't want to mess with the biasing resistor and instead replace the 5Y3 rectifier tube with a NOS 5Y3, seeing as the modern construction of these 5Y3s are not true 5Y3 and will place a higher B+ voltage than in the original circuit. I took some measurements, and my B+ Voltage is 393VDC. This is larger than what the standard reading of 370VDC should be. I know my power transformer isnt the cause of this because I am recieving 375VAC where it should be about 380VAC, which I believe is well withing tolerance.
What do you guys think? Im still learning about amplifier construction and I love the sound of the amp now, but it is running so hot. I mean withing 3 minutes you can't even touch the rectifier or power tubes due to the heat, and the entire chassis is hot within 20 minutes, so I feel this needs to be dealt with before I do anymore tone tweaking with the amp.
I feel I should also state that I have also tried a solid state bridge rectifier using 4 1N4007 diodes just to test out the sound using a SS rectifier, and the overheating still occurs.
Thanks so much guys. Any input is helpful.
I first thought to check the bias of the amp, thinking this was the prime cause of the overheating, I did the calculations and I got 41mA on the output tubes each. This is almost 120% dissapation. This seems like a major issue. However I dont know how to correct this. I have the standard 270 Ohm bias resistor, I figured that if I replaced it with a 330 Ohm resistor this would put me back down to about 96% which sounds about right for a Deluxe.
I've read on some forums where people say that you don't want to mess with the biasing resistor and instead replace the 5Y3 rectifier tube with a NOS 5Y3, seeing as the modern construction of these 5Y3s are not true 5Y3 and will place a higher B+ voltage than in the original circuit. I took some measurements, and my B+ Voltage is 393VDC. This is larger than what the standard reading of 370VDC should be. I know my power transformer isnt the cause of this because I am recieving 375VAC where it should be about 380VAC, which I believe is well withing tolerance.
What do you guys think? Im still learning about amplifier construction and I love the sound of the amp now, but it is running so hot. I mean withing 3 minutes you can't even touch the rectifier or power tubes due to the heat, and the entire chassis is hot within 20 minutes, so I feel this needs to be dealt with before I do anymore tone tweaking with the amp.
I feel I should also state that I have also tried a solid state bridge rectifier using 4 1N4007 diodes just to test out the sound using a SS rectifier, and the overheating still occurs.
Thanks so much guys. Any input is helpful.
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