Help with Mark V 90w

[Wynken]

Hello

I just bought a second hand Mark V and it sounds fantastic on most channels.

I only notice that on channel 1 in Tweed mode, when the gain is over half, if the bold switch is not activated a kind of clipping is heard, I switch to normal and it sounds fine. This at all powers, I have changed all the power and preamp tubes and it continues to generate the noise.

I also noticed that on channel 1 and 2 when changing to a tube rectifier at 45w power the switch does not generate any change, I even removed the 5U4AG and still the sound is heard, even in 10w mode, where it should not be heard, it is heard completely.

I hope you can guide me with this problem.

 

[rarebitusa]

I even removed the 5U4AG and still the sound is heard, even in 10w mode, where it should not be heard, it is heard completely.

hmmm, the relay RYR provides the global switching between tube and rect modes. It'd be one to look at.

Is there a significant volume difference between the 10W & 45W modes?

 

[Wynken]

hmmm, the relay RYR provides the global switching between tube and rect modes. It'd be one to look at.

Is there a significant volume difference between the 10W & 45W modes?

I replaced the rectifier tube and the noise on Channel 1 stopped.
Even in 45W mode on both Channels 1 and 2 there is no big difference when changing the rectification mode. There is no difference in volume, tone or any click or crack, and I don't perceive any sound.
The volume difference between 10W and 45W mode is almost half.

 

[Eevil]

I replaced the rectifier tube and the noise on Channel 1 stopped.
Even in 45W mode on both Channels 1 and 2 there is no big difference when changing the rectification mode. There is no difference in volume, tone or any click or crack, and I don't perceive any sound.
The volume difference between 10W and 45W mode is almost half.

Did you try it with higher volume levels? That’s where the tube rectifier and wattage selection really starts to kick in.

Rectifier selection is not such a huge change but more of a subtle difference.

 

[Wynken]

Hello, yesterday I was able to perform the test, and even at maximum volume there is no perceptible effect. The sound, tone, volume and feel remained intact.

 

[Eevil]

Hello, yesterday I was able to perform the test, and even at maximum volume there is no perceptible effect. The sound, tone, volume and feel remained intact.

And with 45W mode?

Sounds like the amp has some other issue(s) than just tubes.. remote debugging is a pain and my knowledge about the amp’s innards is all in all very limited so I cannot help further with that.

Let’s hope some more educated person can chime in

 

[rarebitusa]

Sounds like the amp has some other issue(s) than just tubes..

yea, I'd agree the relay switching on the V is involved. I doubt tubes at this point but there is limited info to work off of TBH