amp with low volume and distortion

[vlljpior]

Hi, i need help ! i have a amp that the power amp gave only some noisy distortion. Whan i just use the preamp the signal is clean and o.k. but when i take the power amp the only thing i can hear is a tiny clean sound and i have to turn up the volume to hear some noisy distortion of my sound.. What i can do , what do you think might be the problem ?

Thanks
DAn

 

[gmphadte]

Most probably the output power transistors are fried. Check for blown fuse(s), if there are.

Gajanan Phadte

 

[vlljpior]

O.K. but i heard the hum of the amp go up when i turn up the volume. If it was the output transistor i should hera nothing ?

 

[jan.didden]

O.K. but i heard the hum of the amp go up when i turn up the volume. If it was the output transistor i should hera nothing ?

Not clear to me: are you using the power amp on itself or driven by the preamp? Please be a bit more specific on the setup in the two cases. Is the potmeter part of the preamp or in the power amp?

Jan Didden

 

[vlljpior]

So, there a preamp that have a tonestack with a volume pot at the end of the preamp section that drive the power amp section. When i use only the preamp to drive the line out ( connection done just after the master volume ) the amp sound perfectly.

if i drive speaker via the power amp, now, the amp have a lot of distortion. My clean chanel sound like a overdrive chanel. I have to turn up the volume to begin to heard something and the only think i heard is my guitar sound with a lot of distortion, like if there something that was almost blocking the signal. I have to play hard on the string to heard my music who have some difficulty to go true the power amp. no sound and suddenly a distortion sound go out with a lot of noise...?

What can it be ?

 

[jan.didden]

Is this a stereo amp? If so, are both channels having the same problem?

Can you separate the line out from the power amp in? If so, what happens if you directly connect your source (guitar?) to the power amp? Play it soft!!!

Have you tried the speaker(s) on another power amp, and were they OK?


Jan Didden

 

[vlljpior]

tell me your email adress then i will senc you the schematic

 

[anatech]

Hi vlljpior,
Sounds like you are using a guitar amp. Please send the schematic and I'll have a look too. You could post the make and model so more people can help out as well.

bhome at sympatico dot ca

You don't have anything plugged in to a jack you arn't using do you?

-Chris

 

[vlljpior]

I just send you the schematic. Like i told the preamp schection work fine. itM's just the power amp that is in trouble. The amp: Rocktron Rampage R80

 

[anatech]

Hi vlljpior,
You have mail. The attachment was not there.

-Chris

 

[anatech]

Hi vlljpior,
I'd be looking at the headphone jac contacts. It killes the amp input when a plug is inserted. The preamp out is fed differently.

-Chris