I connect in 2466 a attenuator in a bad way

[Roger]

Hi.

Sorry for my english is horrible.
I have a 2466 that will function perfectly. I connect in 2466 a attenuator in a bad way. (BIG BEN is the brand) attenuator is very simple operation only has two positions switch. -9dB And -12dB. The problem is to connect it backwards . Output amplifier attenuator output to speakers. Output amplifier attenuator output to speakers. I do not know if I explain myself. The amplifier worked for 1 minute and then two power valves and OT fuse explode. I changed all the valves, I have adjusted the bias and have spare fuse. The amplifier works everything perfectly but a slight noise is heard. If the master volume is at 0 you can not hear anything but increases as you go up the master volume. It is a transformer noise, huummm. It's curious only be seen in the low range mode and when the master volume from 1 to 7. From 7 to 10 disappears. It is not annoying. I think this clearly is a problem of power amplifier. The preamp works fine. I think it may be some capacitor bud I don't know. Can someone direct me where I can start checking components? Someone advised me to change some components? I have experience in making modifications and repairs amplifiers. I have made several mounting kits amplifiers and pedals.

Thanks for the attention

bye and above all a lot of rock.

[surfnorthwest]

The fuses protected your amp and did what they were suppose to do, so I think the amp is fine. The hum you hear might be from the new tubes you installed. When you removed the amp from the chassis did you inspect it? Look closely at the board and around the tube sockets for a burn on the board.

[Roger]

Hi. I remove the amp from chassis and the pcb power amp board and check all. I don't see anything wrong. Conections. Resistors. I try with other preamp valve.
All is fine.
Probably a diode .

[Roger]

I try with others speakers, others guitars and wires. I have more tube amps. The noise is not normal.
Probably in future the noise will be high. I don,t know.
Today I assemby the amp. I play it two hours. The noise persist.

[Roger]

Hello. the noise level has risen . It affects the two ranges . I've been with good technical service for repair . I continue to report . Now you know never connect a attenuator backwards.

[Migsilva]

Hello Roger, i have the same problem with noise from the master volume from 1 to 7. Did you get any conclusion on your repair?

[Roger]

Hi.
The tech replace master volume pot, the noise continues somewhat less. The tech says the master volume pot it's weak.

[surfnorthwest]

It is never good when your amp is not working right. Hopefully your amp tech can sort things out and get it back where it should be. I do not know what he means by "the master volume pot is weak".

[Roger]

The amp works right. The tech replace master volume pot and the noise going down bud persist.
Sorry for my english is horrible.

[surfnorthwest]

No problem with English, I understand. Happy it is working now. The pots on an amp can go bad and make noise.

[Anitoli]

So the noise isn't as loud as before but is still there and wasn't there before the screw up with the attenuator? Is this correct?

[Roger]

Hi.
It's correct.
Thanks for reply.

[Roger]

Hi.
Anitoli. Do you have any idea about this noise?
Thanks

[Roger]

Hi

I have another problem in my VM that I think is related to the famous noise. Master Volumen down a bit when the button is pressed fx. I almost never use my VM with effects but when I do, I use a boss GT5 and with this multi effects volume loss is not appreciated. But yesterday I tried it with a Marshall SupaWah and with this pedal the volume loss is really appreciated. Also if I use the send signal to another amplifier is amplified much more noise. I read in this forum the problem of FET transistors on the FX board and I have already buy several FET1, FET2 and FET3. When the order arrives I will change one to one. Let's see.

Sorry for my english is horrible

[SteveD]

If the problem is with the SEND then it's going to be FET3. FET1 and FET2 are on the RETURN side.