Search found 4 matches

by ehalvorsen
Fri Feb 10, 2017 7:04 pm
Forum: Series One
Topic: Series One intermittant sound cut out
Replies: 4
Views: 12830

Re: Series One intermittant sound cut out

Clean or replace the standby switch.
by ehalvorsen
Mon Jan 30, 2017 8:33 pm
Forum: Series One
Topic: S1-45 Bias PR1
Replies: 6
Views: 13442

Re: S1-45 Bias PR1

This was the answer I got which I referred to: Hi Espen, With your Digital volt meter set to its 200mvDc range measure across CON 1 on the power valve pcb and adjust PR1 on the power supply PCB to get 50mv, We bias at 25mv per valve, Leave PR1 on the preamp valve pcb in its midway position, If you n...
by ehalvorsen
Thu Jan 26, 2017 8:28 pm
Forum: Series One
Topic: S1-45 Bias PR1
Replies: 6
Views: 13442

Re: S1-45 Bias PR1

The recommended voltage which I got from Blackstar today is:

CON1: 50mV
Adjust with PR1 on the powersupplyboard.

The PR1 on the preampboard shall be just in the middle IF your new tubes are matched. Otherwise, adjust until hum is gone.

The Mesa EL34 sound amazing by the way :)

/Espen
by ehalvorsen
Tue Jan 24, 2017 9:27 pm
Forum: Series One
Topic: S1-45 Bias PR1
Replies: 6
Views: 13442

S1-45 Bias PR1

Hi I just bought a used Series One 45 (2010-model), which had bad tubes. I am installing 2x new Mesa EL34 and all new preamp tubes. What is the correct bias voltage in mV measured on CON1? PR1 on the largest board seems to be the right pot for bias. But on the preamp-board there is another PR1 pot. ...