ET250S warm up behaivior

[st1050@gmail.com]

My ET250S, after the clicks of the relays, in very low volume, the left channel presents a crackling/distorted sound. Betting on tired tubes, I've swapped their positions. Problems persisted on the same channel. Speakers are good for sure. After 8 or 10 minutes, symptoms disappear. I'm aware that tube amps need to warm up, and 10 minutes would be a fine amount of time, but what caught my attention was the fact that only one channel presented the distortion...
Can you tell me your experience or if you know what is wrong?

[admin]

Hard to say. To 100% rule out tubes they would need to be replaced but if you switched them and still the same channel I would say it would be unlikely. It could be a contact problem and as it warms up and there is heat expansion the connection is established. Similar situation with a cold solder joint.

I would start with a visual inspection of the circuit board looking for signs of damage, burn marks, bulging caps, etc. Continuity testing (with the unit off and unplugged). The physical stress testing of components when the unit is on to see if putting pressure on components and connectors causes abnormal sounds (this should be done with a non-conductive item and very carefully as there are potentially lethal voltages on these components.

[st1050@gmail.com]

I've been chatting with a technician, and he said the same thing. He also asked me to check the bias adjustment of the SS stage.

Tks for the input!

[admin]

Let us know how the investigation turns out. Good luck.