unwanted distortion and crackle with laney bass amp

[adamn]

HI,got this bass amp from someone.The amp had this distortion and crackle sound when play..The note could still be heard but die quickly!
Need someone to direct the problem is cause by the power supply, power stage or the preamp.
Could kind soul here help me to solve the problem.Below is the schematic for the amp.

http://www.tremolo.pl/Firmowe/LANEY/RBW200.pdf

[joecool85]

HI,got this bass amp from someone.The amp had this distortion and crackle sound when play..The note could still be heard but die quickly!
Need someone to direct the problem is cause by the power supply, power stage or the preamp.
Could kind soul here help me to solve the problem.Below is the schematic for the amp.

http://www.tremolo.pl/Firmowe/LANEY/RBW200.pdf

A better explanation of the problem would help.  But from the short bit you gave us, sounds like your power supply's electrolytic caps may have shorted out.  If you pop open the amp and look at them they will probably be all corroded, exploded or leaking.

[adamn]

A better explanation of the problem would help.  But from the short bit you gave us, sounds like your power supply's electrolytic caps may have shorted out.  If you pop open the amp and look at them they will probably be all corroded, exploded or leaking.
[/quote]

Thanks for the replay.It a old bass amp.When i plug in my bass,the sound is distorted and cracking,very obvious with the low string.
The guy who pass me the amp mention that he have not been using the amp for years.
I open up the amp and check the elect cap seen ok to me(no corroded, exploded).

How to to check for leakage for the cap?
Could it be the power amp stage that cause the problem?(it an old amp)
Thanks for any help

[joecool85]

While plugged into the amp, if you take the cord coming from your bass and wiggle it around or rotate it, does it make a bunch of noise?  If so, you probably just have a dirty input jack.  This could be causing most of your issues.

[adamn]

Don't think is the jack,i have try other jack but still the same.
It's could clearly hear that some thing is wrong with the amp and the amp don't sound right.
Guess i'll try replacing the elect cap and hope it's work.
If not i have to replace the bipolar transistor or the driver transistor.
Thank for the reply