Tweet
Hi
I have a TA30 ( Rev -1A) I have never seen these before
On start up its fine but after 2-5 mins or so then this noise starts. see picture
Customer has fitted all new JJ tubes. didn't cure the fault.
Remove V4 ( PI) problem goes away. Can see any issues on voltage rails, Tapped about and heat and freezer spray= nothing
Sound_Recordings_26-08-2022-11-55.mp3
Remove V3 = no noise... remove V2 with V3 in place, problem is there but quieter ... remove V1 no change
Can't see any ripple on the voltage rails C-D-E-F
Heater rail look good
up loaded the pictures a little weird the way they have come out
Picture below is at V3 pin 1 HI/2 channel on 40 watt, with gain between 0-1/4
picture at bottom of page is on same point but gain up 3/4
I can see the problem on the scope on pin 1 - 6 of V3 can also see it but lower on pin 6 V2
HI 2 ( red channel)
switched to 40 watt or 15 watt ( no issues with 30 watt)
Master up full , tone 12 oclock , reverb off
(switch to bypass )
0 on gain pot = noise
turn gain pot to 1/4 = quiet
from 1/4 to full = noise
ta30_131002.pdf
Top bst channel ( green)
Same as above but much quieter
I have a TA30 ( Rev -1A) I have never seen these before
On start up its fine but after 2-5 mins or so then this noise starts. see picture
Customer has fitted all new JJ tubes. didn't cure the fault.
Remove V4 ( PI) problem goes away. Can see any issues on voltage rails, Tapped about and heat and freezer spray= nothing
Sound_Recordings_26-08-2022-11-55.mp3
Remove V3 = no noise... remove V2 with V3 in place, problem is there but quieter ... remove V1 no change
Can't see any ripple on the voltage rails C-D-E-F
Heater rail look good
up loaded the pictures a little weird the way they have come out
Picture below is at V3 pin 1 HI/2 channel on 40 watt, with gain between 0-1/4
picture at bottom of page is on same point but gain up 3/4
I can see the problem on the scope on pin 1 - 6 of V3 can also see it but lower on pin 6 V2
HI 2 ( red channel)
switched to 40 watt or 15 watt ( no issues with 30 watt)
Master up full , tone 12 oclock , reverb off
(switch to bypass )
0 on gain pot = noise
turn gain pot to 1/4 = quiet
from 1/4 to full = noise
ta30_131002.pdf
Top bst channel ( green)
Same as above but much quieter
Attached Files