Only modern setting works on dual recto

[factorevif]

Hey guys, I've had my dual stashed away in a roadcase for a few months and let my buddy borrow it. I haven't played the thing in a long time but he said that only the modern setting on channels 2 and 3 would work when he tried it. What would cause this?

 

[KH Guitar Freak]

Check your preamp valves to see if they all work properly first I would say...

 

[94Tremoverb]

It can't be a tube - channels 2 and 3 use the same tubes all the time no matter which mode they're in. I did think it could be a relay, but I checked the schematic again and there isn't one that would kill the sound in the other two modes even if it was stuck - all the modes do is re-voice the channels by adding extra parts and re-routing the negative feedback, they don't interrupt the signal path at all.

I can't actually see anything at all in the signal path that could give that fault. If it is really doing that, I think it must be some sort of problem with the switching control circuit that's doing something totally odd, like operating the muting circuit (which is to suppress relay pops) when it should be operating the relays.

 

[Jak0lantern01]

I second the replacement of tubes..........

 

[94Tremoverb]

*It can't be the tubes.*

If either of the tubes for channel 2 and 3 was out, *none* of the modes on either channel would work. Only V2 and V3 affect these two channels and both are used all the time in all modes on both channels.

There's no point in changing things that aren't going to fix the problem. Have a look at the schematic and you will see that the tubes cannot be the cause of this.

http://www.schematicheaven.com/boogieamps/boogie_dualrectifier_3ch_solo_head.pdf

 

[mikey383]

*It can't be the tubes.*

If either of the tubes for channel 2 and 3 was out, *none* of the modes on either channel would work. Only V2 and V3 affect these two channels and both are used all the time in all modes on both channels.

There's no point in changing things that aren't going to fix the problem. Have a look at the schematic and you will see that the tubes cannot be the cause of this.

http://www.schematicheaven.com/boogieamps/boogie_dualrectifier_3ch_solo_head.pdf

This.

Although, '94, you would have to be able to read a schematic in order to find that out. If they can't read one, then it's just going to be Japanese to them.



It isn't tube related. If either V2 or V3 were bad, it would render the distortion channels useless, irregardless of raw/vintage/modern. Those tubes would affect any settings on those 2 channels. They are the gain boost tubes for those channels. If either tube were bad, there would be no sound, or a thin sound on both channels and all settings.

The only thing I could see that may cause that problem is a diode in the channel voicing.

 

[eventide_awakening]

I think it must be some sort of problem with the switching control circuit that's doing something totally odd, like operating the muting circuit (which is to suppress relay pops) when it should be operating the relays.

I had a muting circuit issue recently due to a surge (long story). This caused volume fluctuations over all my channels and it didn't matter which mode or 'voice' I used. The volume would drop out and become very faint and then return to normal volume. This progressively became worse over time until I couldn't hear anything at all.