I need help!!!

[vlmarques]

Hi! I have a mkV about 2 months and it started some problem and I'm desperate because I have no technical assistance in Brazil.

The problem started simply with the red led of channel 3. It simply goes off. Nothing happened to the sound so far. After some days, the sound started to fade out when the loop is on (I use it on all the time because of my effects). It fades in and out randomly. When I turn the loop off the sound comes back. It takes about 10 minutes so the problem ends. But I'm seriously worried if it could get worse.

It seems that the led problem and the loop problem are independent because they don't necessarily came together.

Please help!

 

[eudaimonia02912]

Bom dia,

I'm not sure about the LED. However, I think it is highly likely that you have a bad pre-amp tube. Because it is affecting the loop, it is most likely V6, the pre-amp tube that is second closest to the fan. Replace that with a brand new 12AX7, and see if it fixes the problem.

 

[Scary]

Is it just channel 3? or do all channels that use the loop fade out? I had a problem like that with my FIVE and I swapped ends of the footswitch cable and it's worked great ever since. My mark iv on the other hand has had intermittently working led's for years... it doesn't seem to change the tone though.

 

[rika_gd]

are you connecting the amp straight to the wall or using some adapter?

 

[vlmarques]

are you connecting the amp straight to the wall or using some adapter?

the amp goes to the power conditioner and then to the wall with no adapters.

Is it just channel 3? or do all channels that use the loop fade out? I had a problem like that with my FIVE and I swapped ends of the footswitch cable and it's worked great ever since. My mark iv on the other hand has had intermittently working led's for years... it doesn't seem to change the tone though.

Some times is just the channel 3. other it happens in all channels. I've tried to swap the cable but didn't work.

I'll try now to replace the loop tube and hope to work.

 

[rika_gd]

my sales man told me that this amp its very sensitive in terms of electricity, so i had a problem when i connected it srtaight to the wall..the ch 3 in 90w didnt work right..same for ch2 so thats why i asked

 

[vlmarques]

I've tired to change the loop tube. I've replaced it with a working fine JJ tesla ecc83 from another amplifier. But the problem is still happening. I've talked to a good tube amplifier handmaker and I will take the amp for him to give a look.

As soon as I have a answer from him I'll post it here.

 

[ixoye777]

I had a similar problem a few weeks back - it was the footswitch cable.