Yesterday, for some reason, none of my distortion channels worked. They produced a clean sound only. There was very little volume as well. The clean channels were more quiet than 3 and 4. The reverb button didn't seem to do anything either. I cranked the main volume all the way up a there wasn't much of a volume difference. For practice purposes, I used my multi effects pedal (which is in the fx loop) for distortion and it was decent. What do you think is wrong?
Mesa Boogie Roadster no distortion, no reverb, low volume?
- Thread starter Hybrid138
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ryjan
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Could be a hundred things.
Tubes
Internal damage
cable
connection
operator error
on, and on, and on........
Either take it to a tech or edumacate yourself on how to do basic tube amp troubleshooting. Asking what's wrong on a forum without any info or pictures is impossible.
Tubes
Internal damage
cable
connection
operator error
on, and on, and on........
Either take it to a tech or edumacate yourself on how to do basic tube amp troubleshooting. Asking what's wrong on a forum without any info or pictures is impossible.
I would agree with ryjan. The Roadster is not all that complex like a Mark V. I would run down the basics first and follow though with some tube trials to determine if there is a tube fault.
Start with the basics first. Does the amp improve or get worse with the loop in hard bypass? Try disconnecting the footswitch cable and use the rotary selector under the cable jack for each channel. If no improvement, there could be a tube related issue. If it is one or both of the Rectifier tubes, set the switch to diode on all channels, remove the Rectifier tubes (do this with the power off and cold tubes). I have had a Rectifier drop out the power supply even though it was bypassed in a Mark V. I know, the Roadster is quite different but will work if you select diode tracking and remove the Rectifier tubes (methinks).
If there is no difference to CH1 and CH2, I would doubt there is an issue with V1 or V2 (with the exception of half of V2 is used with CH3/CH4). If you have a good known tube consider the first tube that may isolate the problem. I would start with V2 and move up the chian. Probable issue may be with V3 (4th and 5th gain stages of CH3 and CH4 only, will not effect CH1 or CH2).
Lack of reverb could either be V4 (mostly the cause) However, (this will be a wild guess but may be on track since the newer designs are using JFETs to activate and deactivate / attenuate the reverb circuit) you may have a dead JFET (when they go, they will pull the screen down to a relatively low impedance (80 to 90 ohms). It could also be a relay, or unconnected or loose terminals on the reverb.
The diagnosis becomes more difficult if you cannot isolate it by swapping a tube.
Start with the basics first. Does the amp improve or get worse with the loop in hard bypass? Try disconnecting the footswitch cable and use the rotary selector under the cable jack for each channel. If no improvement, there could be a tube related issue. If it is one or both of the Rectifier tubes, set the switch to diode on all channels, remove the Rectifier tubes (do this with the power off and cold tubes). I have had a Rectifier drop out the power supply even though it was bypassed in a Mark V. I know, the Roadster is quite different but will work if you select diode tracking and remove the Rectifier tubes (methinks).
If there is no difference to CH1 and CH2, I would doubt there is an issue with V1 or V2 (with the exception of half of V2 is used with CH3/CH4). If you have a good known tube consider the first tube that may isolate the problem. I would start with V2 and move up the chian. Probable issue may be with V3 (4th and 5th gain stages of CH3 and CH4 only, will not effect CH1 or CH2).
Lack of reverb could either be V4 (mostly the cause) However, (this will be a wild guess but may be on track since the newer designs are using JFETs to activate and deactivate / attenuate the reverb circuit) you may have a dead JFET (when they go, they will pull the screen down to a relatively low impedance (80 to 90 ohms). It could also be a relay, or unconnected or loose terminals on the reverb.
The diagnosis becomes more difficult if you cannot isolate it by swapping a tube.
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