Forums - Print Page

Forums
https://www.decware.com/cgi-bin/yabb22/YaBB.pl
AUDIO FORUMS >> General Discussion and Support >> Rachael Problem - Pop and Bias Meter to 100
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1756388375

Message started by Alan Arkin on 08/28/25 at 14:39:35

Title: Rachael Problem - Pop and Bias Meter to 100
Post by Alan Arkin on 08/28/25 at 14:39:35

Hi there -

So this morning when I powered on my system as I always do, after a few moments, I realized that there was a dull pop coming from the right speaker. (It took me a minute to realize this). When I went over to the system, I saw that the right meter was at 100. I turned my system off and checked that all the tubes and connections were as they should be. (I had just dusted and thought maybe I nudged something). I tried again and it happened again, and once more, and it still happened. When it turned on it looked like the bias meter went to 40 and then jumped to 100 a few moments later.

Any idea what this could be? I guess I will swap out the tubes -- though not sure if that would be the power tube or the input tube. But is it likely to be something other than tubes?

Thanks.

-- Alan

Title: Re: Rachael Problem - Pop and Bias Meter to 100
Post by CAJames on 08/28/25 at 15:00:22

Quote:

Posted by: Alan Arkin Posted on: Today at 06:39:35

...Any idea what this could be?

Tubes. The meter reads the current on the power tube so that is where I'd start, then the rectifier and then the input tube.

Title: Re: Rachael Problem - Pop and Bias Meter to 100
Post by Alan Arkin on 08/28/25 at 15:26:16

Thanks. I think it was a bad KT77. I swapped out my power tubes and the meters are holding steady at 40. So crisis averted.

Title: Re: Rachael Problem - Pop and Bias Meter to 100
Post by CAJames on 08/28/25 at 15:54:23

Happy to help. I think it is safe to say when something different/strange/bad happens to the amp your first, and probably second thought should be "tubes." After that there are things like fuses and heatwave related power sags to consider.

Title: Re: Rachael Problem - Pop and Bias Meter to 100
Post by Alan Arkin on 08/28/25 at 16:05:20

And now on to shopping for a new set of power tubes!

Title: Re: Rachael Problem - Pop and Bias Meter to 100
Post by Yakatak on 08/29/25 at 02:12:56

NOS 807 :)