Peavey Classic Chorus 212

[sniper1]

Peavey Classic Chorus 212(NOT STEREO CHORUS).1)On/Off switch only works if I give amp slight kick.-2)Reverb sounds like a siren when turned on.-3)With guitar plugged in,I can control?? amp hum with guitar volume knob.This is a great amp for being SS.still has the Scorpion speakers,would hate to trash it if the fix is not worth it.

[J M Fahey]

1)On/Off switch only works if I give amp slight kick.-

Bad contact, unfortunately on the single most DANGEROUS AND DEADLY part of your amp: the mains section.
Try to send it to somebody with experience.

2)Reverb sounds like a siren when turned on.-

Disconnect the return RCA plug on the amp side and plug there a shorted RCA jack: what happens? still the siren?

3)With guitar plugged in,I can control?? amp hum with guitar volume knob.

Then it's probably a guitar issue.
With the guitar "on" move around, rotate, sit and rise: does the hum change?
Is your guitar single coil?
Try with another guitar cord.

[Enzo]

The reverb, does the siren come on immediately when you turn the reverb on, or does it take a couplpe seconds to build up to a roar?  Reverbs can feed back acoustically, and if it takes a couple seconds to get there, that is what is happening.

If it is immediaste, the connections to the pan could be reversed, or other odd things wrong.

[sniper1]

1)On/Off switch only works if I give amp slight kick.-

Bad contact, unfortunately on the single most DANGEROUS AND DEADLY part of your amp: the mains section.
Try to send it to somebody with experience.

2)Reverb sounds like a siren when turned on.-

Disconnect the return RCA plug on the amp side and plug there a shorted RCA jack: what happens? still the siren?

3)With guitar plugged in,I can control?? amp hum with guitar volume knob.

Then it's probably a guitar issue.
With the guitar "on" move around, rotate, sit and rise: does the hum change?
Is your guitar single coil?
Try with another guitar cord.

1)will send amp to expert.2)whats a shorted RCA jack?3)Fender Strat(3 SC).

[sniper1]

The reverb, does the siren come on immediately when you turn the reverb on, or does it take a couplpe seconds to build up to a roar?  Reverbs can feed back acoustically, and if it takes a couple seconds to get there, that is what is happening.

If it is immediaste, the connections to the pan could be reversed, or other odd things wrong.

The reverb takes a few seconds to build up to the siren sound,Turn reverb knob to say 6, no sound at first,wait a few seconds and I can hear the siren start to build up non stop,how loud will the siren get?I don't want to blow the speakers.LOL

[J M Fahey]

Then, as Enzo guessed correctly, your reverb sprongs are feeding back because the speaker makes them vibrate.
Manufacturers use various "medicines" to avoid it, none of them very effective, but if you use many ....
Obviously that defect didn't exist when the amp was new.
Manufacturers do:
1) the spring sub-chassis "floats" inside a larger metal box, suspended by 4 tiny springs. If one or more stretch or unfasten and the subchassis touches the box: it feedbacks.
2) that box is held to the cabinet side or bottom by 4 screws that go through soft rubber rings, If they are old they crystallize or become a sticky goo; replace them.
The screws are *not* tightened, they are loose and let the box bove around a little.
A typical un-experienced owner tightens them. Mistake !!.
3) Fenders wrap the box in cotton-like padding, and stuff that into a Tolex envelope, lightly fastened to the bttom of the amp.
To avoid the cotton touching the reverb springs, they close the box with a piece of cardboard.
I see you get the point: "float" or decouple mechanicaly the reverb tank from the vibrating cabinet.
Some players, Paul Young and Dick Dale come to mind, mount their reverb tanks in another enclosure *away* from the main amp, even in another room or under the stage.

[sniper1]

Then, as Enzo guessed correctly, your reverb sprongs are feeding back because the speaker makes them vibrate.
Manufacturers use various "medicines" to avoid it, none of them very effective, but if you use many ....
Obviously that defect didn't exist when the amp was new.
Manufacturers do:
1) the spring sub-chassis "floats" inside a larger metal box, suspended by 4 tiny springs. If one or more stretch or unfasten and the subchassis touches the box: it feedbacks.
2) that box is held to the cabinet side or bottom by 4 screws that go through soft rubber rings, If they are old they crystallize or become a sticky goo; replace them.
The screws are *not* tightened, they are loose and let the box bove around a little.
A typical un-experienced owner tightens them. Mistake !!.
3) Fenders wrap the box in cotton-like padding, and stuff that into a Tolex envelope, lightly fastened to the bttom of the amp.
To avoid the cotton touching the reverb springs, they close the box with a piece of cardboard.
I see you get the point: "float" or decouple mechanicaly the reverb tank from the vibrating cabinet.
Some players, Paul Young and Dick Dale come to mind, mount their reverb tanks in another enclosure *away* from the main amp, even in another room or under the stage.

I did replace the rubber feet,however I also tightened the reverb pan screws down tight,I'll have to loosen them.

[Enzo]

Cranking the screws down tight guarantees the vibration from the cabinet will be fed into the reverb pan.  if your pan is not in a reverb pan bag, consider getting one.  Cut a piece of cardboard to cover the open side of the pan and tape it in place.   And it can matter where in the cab the thing sits.  Try moving it around - as far as space allows.

ANother trick is to get some of that rubber weather strip like you put along a garage door.  Peel off adhesive back, rubber about 1/2 to 3/4" wide and maybe 3/8" thick.  Clean off the wide flat top surface of the pan.  GLue a stripe of the weatherstripping down the center of the flat surface.   That will keep the flat side from resonating.  Auto makers do this inside large car body panels to cur down on sheet metal noises.