Installing a 3 prong wire & plug

[pbman1953]

I bought an Acoustic 150B bass amp that has a 2 prong. After I install the 3 prong wire , would I need to disconnect the grounding switch?

[Dave]

Yes, and the associated capacitor is typically referred to as the "death cap". It should be removed.


Dave

[pbman1953]

Yes, and the associated capacitor is typically referred to as the "death cap". It should be removed.


Dave

Would it be enough to snip the one side of the 47k resistor to take it out of the circuit?

[WimWalther]

Would it be enough to snip the one side of the 47k resistor to take it out of the circuit?

You mean R401, the 4K7 resistor in series with the neon? No, you need that, assuming the neon is your pilot lamp.

Just remove C403.

[pbman1953]

Would it be enough to snip the one side of the 47k resistor to take it out of the circuit?

You mean the 4K7 resistor in series with the neon? No, you need that, assuming the neon is your pilot lamp.

Just remove C403.

You're right, saw that. I cut the wire leading to the cap

[pbman1953]

Next question, I think there's a bit of 60 cycle hum, would a new filter cap solve that?  There's 1- 3200 uf/ 75v computer grade cap


I sent a schematic of the power section.


Which other electrolytics would be best to change?

[WimWalther]

Next question, I think there's a bit of 60 cycle hum, would a new filter cap solve that?

No idea. Depends what's causing the hum, eh?

There's 1- 3200 uf/ 75v computer grade cap

Sorry, not seeing it. What's the p/n?

Which other electrolytics would be best to change?

The bad ones? ;-)

In most cases, the first cap after the rectifier takes the most abuse. If you're all about replacing caps, start with that one and go from there.

[WimWalther]

Btw, you don't necessarily need to remove / disable a grounding switch when installing a 3-wire cord.

The Peavey KB300 came from the factory with a 3-wire and a grounding switch. See attached.

[Soulfetish]

Any capacitor from AC line to chassis needs to be a safety "Y class" rated capacitor. These are specially rated and tested capacitors designed for this purpose.
If someone is updating a 2-wire AC input, they need to cut the original capacitor out. This cap has a real risk of failure. I've seen them fail, even when used at 120V mains.

[pbman1953]

I'm going to do them all. Due to the age , why not




Thanks for the help!

[mresistor]

Yes here's info on safety caps  https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/


https://www.mouser.com/ProductDetail/Vishay-Roederstein/F17103471000?qs=bIueFxc6GScX5iPnm5V%2FAA%3D%3D

[WimWalther]

Simple rules..

Think of an "X" type cap as a "cross", as it goes 'across' (between) the AC live & neutral lines.

Think of the "Y" type as a "wye" connection, as in one cap each from line & neutral to AC ground.