Michael Rubin
845 posts
Jan 07, 2014
12:17 AM
|
Hey everybody, thanks in advance. I have a 59 bassman reissue and it has been a LONG time since I've changed the tubes. Tonite at the gig the volume went off and on. After 3 songs I borrowed a house amp.
I am assuming I just need power tubes, but any other ideas? I will probably take it to an amp Doctor just to see if he agrees with me.
Thanks!
|
Kingley
3375 posts
Jan 07, 2014
12:25 AM
|
Is your mic lead ok?
Is the mic ok?
Have you tried all the inputs to rule out the socket being the problem?
Have you checked the speakers for any loose wiring?
Have you checked the wiring on the plug?
It could be the valves, but if you haven't already I'd check the mic and lead with another amp first to rule that out and all the above. If you have valves of the same value laying around put them in and give it a test. It should be ok for a short test without a rebias. If the problem persists then take it to an amp tech.
Last Edited by Kingley on Jan 07, 2014 12:25 AM
|
MagicPauley57
157 posts
Jan 07, 2014
12:54 AM
|
Also check the pre-amp valves in position one and two, check both channel inputs hi and lo, I had an incident when bright/ vib channel lost volume, I put in a new 12 ax7 as it had burnt out due to trying an at7 in normal to get more volume, didn't harm the amp in any way, ( super reverb) all back to normal.
If no volume in any channel , check fuse. You shouldn't need to rebias stock preamp tubes and power tubes ( 6l6)
if the amp has been re-biased for at or ay then just put another in, shouldn't need to fettle unless it's been extensively modded
|
5F6H
1730 posts
Jan 07, 2014
2:58 AM
|
Get the tech to check the integrity of the screen grid resistors (R32 & R33, amongst other usual checks), these heat & cool and can desolder themselves from the PCB...working fine one minute, then cutting in/out. Best to remove the old ones and rewire new parts direct to the tube sockets.
Also check R14, R28 & R29.
----------
www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by 5F6H on Jan 07, 2014 3:00 AM
|
Greg Heumann
2553 posts
Jan 07, 2014
9:48 PM
|
Agree with Kingley and others - bad tubes are less likely than many other causes. In addition to what has already been said check to be sure the tubes are fully seated as well. They CAN vibrate loose.
----------
***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
BlueState - my band
Bluestate on iTunes
|
Rick Davis
2835 posts
Jan 08, 2014
9:48 AM
|
A tube is like a light bulb: They tend to work or not. If the problem is intermittent it may be something related to the tube, like a loose socket or a bad solder (as noted above by some fine forum members) but not the tube itself. When power tubes go out they sometimes pop like a light bulb. I hate seeing that flash of light coming out of the back of my amp during a show.
----------
-Little Rick Davis
The Memphis Mini harp amp
The Blues Harp Amps Blog
The Mile High Blues Society
|
walterharp
1272 posts
Jan 08, 2014
11:50 AM
|
yeah, they have those 4 plugs for the speaker leads that often work a bit loose... if needed crimp the outside of the connector (the metal tube bit), just a little bit to tighten up that location.
|
tmf714
2319 posts
Jan 08, 2014
3:24 PM
|
Mark Granfield could tell you in a NYC minute-I couldn't resist-lol.
|
