How would you fix this popping power switch?

[soundguruman]

Believe it or not...
putting a RESISTOR across the switch, like 220K 5Watt, or some other appropriate value, will stop the pop and arcing.
This allows a tiny bit of current to precede the closing of the contacts.
Just as a resistor across the channel switching relay contacts stops a channel switching POP.
No, it will not harm anything. And it lasts forever.
I am surprised that the factory did not think of this.
Yes the amp will draw micro current when it is off, but who cares? It saves your speaker!

FYI this works better than ANY capacitor across the switch!

[AllAmpedUp]

Wow...that is fantastic.
Is there a schematic example of this type of connection?

[AllAmpedUp]

ok, I found this....
In order to achieve long life and high reliability when switching AC currents with inductive or capacitive loads some form of arc suppression or filtering is required across the relay contacts. This is achieved by connecting an RC Snubber network in parallel with the contacts. The voltage peak, which occurs at the instant the contacts open, will be safely short circuited by the RC network, thus suppressing any arc generated at the contact tips. For example see this picture:
Relay Snubber Circuit

Courteous of: RC Snubber Network tutorial at: Electrical Relay and Solid State Relay

Should I just solder the resistor as shown in the diagram.

So.....for a standard Fender 65 Watt AMP with 120v~60hx (180w) listed as the input power (on the back of my amp)...
What is the minimum or max size resistor that should be used?

[JoeM]

Are you sure it's the switch? I dont think the popping is caused only by it, but some difference in the turn off of the output transistors. If you switch off the amp using a power strip for example, does it still pop? The OP in this thread was referring to 5E3, which is a tube amp.

[soundguruman]

Wow...that is fantastic.
Is there a schematic example of this type of connection?

You don't need a schematic, it's just a resistor across a switch. Try it yourself with clip leads.
You can select a resistor that causes the amp to draw about 1-2 ma (sometimes a wee bit more) when the switch is OFF.
And it works every time.
If you notice, we have computers, Tvs, and all kinds of other appliances that draw a small current when they are switched "OFF." This is a "standby" mode of operation.
Same idea here, just primitive...
And if you don't want the small current draw, just UNPLUG it when you are not using it!

[AllAmpedUp]

You can select a resistor that causes the amp to draw about 1-2 ma (sometimes a wee bit more) when the switch is OFF.
And it works every time......
And if you don't want the small current draw, just UNPLUG it when you are not using it!

ok, I am sold and I have technical aptitude....but, as a newbie to electronics, can you clarify the resistor attritbutes that allow me to calculate how much draw it has?
For example, does that 220k 5w resistor (mentioned earlier) have a maximum of 5 watts with impeadance of 220 ohms?

This fender has 1.5 amps input at 180 watts...... I=w/v.....what is the formula to get 1.5ma?

[guitician]

That power switch that Fender uses in the Princeton 112+ is low quality. I had one go bad from not being used. I took it apart and cleaned the oxidation off of the contacts and now it works. They should have used some kind of dielectric grease inside. If yours has been arching, it may be in need of replacing. The resistance of the oxidation will cause a failure later on.

[AllAmpedUp]

That power switch that Fender uses in the Princeton 112+ is low quality. I had one go bad from not being used. I took it apart and cleaned the oxidation off of the contacts and now it works. They should have used some kind of dielectric grease inside. If yours has been arching, it may be in need of replacing. The resistance of the oxidation will cause a failure later on.

It is kind of cheapy...
I was planning to replace with one that has an amber light inside.
If that works, no resistor is needed, thou I still want to know what kind/size resistor is optimal.

I am loving the new knowledge I have gained over last few months as I tinker and troubleshoot.
Its weird, I could tear apart and rebuild an SS carb for my harley, but the dam headlights never worked right....I wish I still had her, I bet I could find that short today....


Thank you everyone who contibutes here.....a very helpful community, indeed!!!

[soundguruman]

It is kind of cheapy...
I was planning to replace with one that has an amber light inside.
If that works, no resistor is needed, thou I still want to know what kind/size resistor is optimal.

I am loving the new knowledge I have gained over last few months as I tinker and troubleshoot.
Its weird, I could tear apart and rebuild an SS carb for my harley, but the dam headlights never worked right....I wish I still had her, I bet I could find that short today....


Thank you everyone who contibutes here.....a very helpful community, indeed!!!

Connect clip leads across the poles of the switch, the two poles that are hooked to the power and the primary of the transformer.
Install a 220K resistor, does not have to 5 watts, could be 1 watt! I use 5 watt just because I overbuild everything.
Now plug it in and turn on the power, does it still POP?
unplug the unit, allow about 5 minutes, install a SMALLER value, like 180K.
Now repeat the test, does it POP?
Continue substitution, smaller and smaller value, until you find the value that prevents the POP from occurring.
Unplug the power between tests, allow the power supply to discharge, so that you can get a fair test.

The best test is where the power supply is discharged. If the power supply still charged, the pop will not occur.

Now that you have selected a resistor by substitution method, solder that pup into the circuit!

[AllAmpedUp]

Ok ....yes, yes, yes...get it now.
I will pickup all the parts on Monday and iteratively find the right combination.

I am so grateful for the suggestion....
I have been taking vids of my work on this amp and I will record this event too.
I plan to post it all on youtube when finished.

Thanks guys!!!

[soundguruman]

Ok ....yes, yes, yes...get it now.
I will pickup all the parts on Monday and iteratively find the right combination.

I am so grateful for the suggestion....
I have been taking vids of my work on this amp and I will record this event too.
I plan to post it all on youtube when finished.

Thanks guys!!!

I invented this method in response to a complaint about CRATE amps.
The CRATE amp would make a loud POP when it was turned on, eventually blowing the speaker.
The crate techs had no solution, so I invented one.
When you post on Utube, be sure to thank CRATE for the inspiration.

[AllAmpedUp]

I invented this method in response to a complaint about CRATE amps.
The CRATE amp would make a loud POP when it was turned on, eventually blowing the speaker.
The crate techs had no solution, so I invented one.
When you post on Utube, be sure to thank CRATE for the inspiration.

I sure will...
In the early 90's the company I worked for moved all thier manufacturing to mexico (NAFTA)
It basically ruined them. Fender is lucky that this series of questionable design produced such an amazing tone.
The Type-C (reverse audio) pot on both the volumes and drive makes me shake my head.

[AllAmpedUp]

Success...Amp is back up again...
new footage on my Droid for a future you-tube video on this subject.
Now, I will Try out a few resistors across the on/off switch to see if we can eliminate or reduce the loud popping when turning amp off But...if that doesn't work, put the speaker toggle back on....lol
Also have a new 8ohm/100w L-PAD power soaker (mostly for the drive channel as I already replaced the Vol-pot for the main channel with a type-a audio)...