conrad/Johnson mv45A

[tion010]

My C/J mv 45A starting smoking When I turn it on .Smoke was coming right side of power tube coming up through the housing .I know it a old amp mated with a control Amp vintage dbx cx-3 vintage Snell speakers k/II it sound magical to me .Any opinions /technical advice will be greatly appreciated. Thanks to everyone in advance for taking the time to understand my situation.

[AnotherJohnson]

Smoke = fire.

Resistor or cap probably failed.

If you are equipped to safely investigate (lethal voltages could still be present), remove casework. Your problem may be obvious due to melting and blackness.

Check your fuses. They’re supposed to prevent this sort of stuff.

If you want it to sound its best, send it back to CJ. If you just want it to work, take it to a local who repairs guitar amps.

[admin]

Safe bet is to send it directly to CJ for repair.

However, if technically inclined I would pop the cover off and look for the damaged components which in your case will probably be easy to identify from the burn marks.

[tion010]

Admin ..... that my next move hoping it would be just as easy as replacing a dead battery in a car instead of wrenches... a soldering iron.

[roberto]

Hola tion010,
You have a bad power tube. And the 5 watts, 20 ohms bias resistor is burned. Usually that's all. It is wise to check all bias resistors for precise ohm value. Replace as needed. Fresh El-34/6CA7 tubes will make to bring back the wonderful sound of your MV-45.

Happy listening!

[tion010]

Thank you Roberto for the valuable information you provided.All I need to do now is learn how to download schematics

[roberto]

mv45a1 schematic and parts.pdf

This is what I have, I hope it will help you with your problem

Happy listening!