Hello to everybody. I just finished building an Elekit TU8600S Lundhal Version. It works very well, no hum and audio quality is excellent. Unfortunately there is a problem: at first power-on the current protection triggers (generally on the right channel, but sometimes on the left channel as well). Then, waiting for a while and switching on again, it goes properly. Of course it is extremely annoying, and one cannot live with it. Any suggestion? The PTCs are the new UN600-200, therefore I do not think they are the problem source. Voltages during normal operation are ok. Thank you for addressing me on the right path.
Moved to Elekit Sorry: I forgot an important symptom in my first post. When the protection triggers, at power on, there is some crack noise from the correspondent speaker, and the filament luminosity of the correspondent 300B tube is perceivably higher...
Thanks again if somebody can address me in the right direction
Thanks again if somebody can address me in the right direction
No, unfortunately I have no any spare 300B. However, as per your suggestion, let me switch the two 300Bs and let me see what happens. As the things are now, from some days the problem is happening on right channel only, and therefore, if your supposition is correct, the problem should move on the left.
Many thanks in the meantime for your hint
Many thanks in the meantime for your hint
Yes. Swop left and right is the fastest way to check. Please stop testing or using the failed tube once you have determined. A failed/shorted tube can be very dangerous.
This was my situation as well, at the beginning. Just at cold start. Then it seems now that the faulty tube is degrading quickly. I prefer following the recommendation of Kimgg, stopping any further attempt, just to avoid fireworks at home 
. I just ordered a new selected pair of 300B, and I can replace them beginning of the next week. I'll tell you how this story will end, after replacement.
. I just ordered a new selected pair of 300B, and I can replace them beginning of the next week. I'll tell you how this story will end, after replacement.Hi Paul, it also happens intermittently for my case at first. Then it start (cracking sound) to appear everytime I ON my amp. That’s where I decided to stop. You should monitor it with you nearby to off the amp in case of anything happening. Good luck!
Hi Kimgg, thanks for the advice I will keep an eye on things.
It's very frustrating after all the fun and hard work to build the amp and to have an intermittent fault.
The valves are all new, Genalex gold lion 300b , JJ ECC 82 and JJ ECC 83.
I don't have the funds to replace them all which liked would have liked to do.
It's very frustrating after all the fun and hard work to build the amp and to have an intermittent fault.
The valves are all new, Genalex gold lion 300b , JJ ECC 82 and JJ ECC 83.
I don't have the funds to replace them all which liked would have liked to do.
Hi folks...
This fault is old. I had it some time ago and I sent messages to elekit japan and never got reply. Using an isolated scope I checked current across limitation resistor and pin 1 of voltage regulator. This was what I found... there was a phantom enable signal before full activation (look at pics, blue is enable pin and red is current crossing resistor)
I tried with some different 300b, and with Gold Lion was not visible but fault was here too. With Elrog one the fault was a lot of visible because filament light is very strong.
This phantom signal in enable pin start the voltage regulator and in few time disable again. So, tube has two start procedure instead only one. How bad is for life of tube, i do not know. In my case, only happened with one channel, and exchange both tubes was the same fault.
I only fixed the fault when used another ecc82.
This fault is old. I had it some time ago and I sent messages to elekit japan and never got reply. Using an isolated scope I checked current across limitation resistor and pin 1 of voltage regulator. This was what I found... there was a phantom enable signal before full activation (look at pics, blue is enable pin and red is current crossing resistor)
I tried with some different 300b, and with Gold Lion was not visible but fault was here too. With Elrog one the fault was a lot of visible because filament light is very strong.
This phantom signal in enable pin start the voltage regulator and in few time disable again. So, tube has two start procedure instead only one. How bad is for life of tube, i do not know. In my case, only happened with one channel, and exchange both tubes was the same fault.
I only fixed the fault when used another ecc82.
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