Randall RG50TC Volume problem

[UnluckyFett]

Hi all, The problem is clean channel is half the volume of the distortion channel. I saw this problem in a dead thread somewhere (EDIT: http://music-electronics-forum.com/t22631/ ) so it must be a common problem in these amps. The schem is attached. The first thing i did was try changing tubes, with no success. If I plug in the effects loop out to a power amp the levels are perfect. So that leads me to believe that the problem is in the effects loop return. I replaced IC3 (and added a socket) but it changed nothing. So now Im leaning towards the zener diodes. But at the same time it doesn't make sense to me that the signals from clean and distorted meet at the switch so why would the effects loop or anything after it affect the level of the channels independently? Unless its because I dont understand how the effects loop works and Im actually misinterpreting the loop out. Anyway, any insight would be helpful, Thanks

randal.pdf

[J M Fahey]

What do you exactly mean by

clean channel is half the volume of the distortion channel

That with both on, say, 5 one is quite louder than the other or that you need to set clean on, say, 7 to match distorted on 5?

[Jazz P Bass]

Try a jumper cord inserted between the effects jacks themselves.
A crude bypass test of the normally closed contacts.
If that solves the issue, the jack contacts are dirty & need to be cleaned.

[UnluckyFett]

That with clean all the way up and gain channel on 5 the gain channel is still way louder.. sorry I can see that how I worded it wasn't ideal

[UnluckyFett]

No difference when jumped or when the line button is pressed

[J M Fahey]

Overdrive/distortion is generated by driving V2B into clipping, so distorted signal there will be around 70/90 V RMS , while clean signal, which also goes through same triode, will not be over 10/15V RMS to be called clean and have some headroom.
That huge level difference is usually compensated by padding distorted signal a lot.
In this case: 1M R154 in series with Vr2 B200K .
I see 2 problems there:
1) VR2 is "B" Linear, replace it with same value but "A" , Audio or Log taper.
2) if still too loud, solder a 220K resistor in parallel with it.
That should take care of the problem.

[g1]

If I plug in the effects loop out to a power amp the levels are perfect.

This is a little confusing. Are you saying the clean level is louder (compared to the Dist. channel) if you plug the FX send into a different power amp? Can you double check this? I don't think it is possible.