# starting up an old amp



## NJPCRX (Jul 25, 2012)

I got a couple late 90's us amps. I don't know how long they have been sitting around. I heard that over time the caps inside discharge and you may be faced with problems when you try to start it up. Is there anything I can do to charge the caps before I hook it up. Like hook a trickle charger to it as if it was a battery? Or is that a bad idea.


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## lostthumb (Dec 16, 2005)

If anything, you will probably need the caps replaced. I am not an expert but I had an older Zapco amp that went bad during bench testing after purchase. The caps were leaking and needed to be replaced but by looking at it with the back of the amp off, I did not see anything wrong. Apparently, I needed to look from the other side of the board.


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## ATOMICTECH62 (Jan 24, 2009)

Putting 12 volts to the amp only charges the caps at that end of the amp.When the remote is connected the power supply starts up and sends voltage through out the rest of the amp.So,no there is no way to do it without turning it on.


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## underdog (Jul 5, 2011)

This was an interesting read
Capacitor


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## NJPCRX (Jul 25, 2012)

How many years do you think it takes to go bad? The guy said it hadn't been too long since they were used. They will probably be good.


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## SaturnSL1 (Jun 27, 2011)

You could probably rig up a Variac to slowly bring up the voltage or maybe use resistors? 

I wouldn't worry about turning them right on though. Turn em on, let em sit there for a few minutes, then give them an audio signal and rock out!


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## NJPCRX (Jul 25, 2012)

I wonder how many us amps have startup problems after sitting. I pray to god they are good!!


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## sqshoestring (Jun 19, 2007)

One way is to use an old car headlight. They only let so much current through and can help keep it from roasting if something is amiss. Another way is use a 10A power supply. If it starts up normally then try using it. I have a 10A PS and then run it through a $5 dvom they handle 10A load. You can watch it pull more power to fill the caps then go back to couple amps idle draw. Depends how big an amp it is, big sub amps take a bit to charge on a 10A PS they can trip it before the caps fill. There are caps before the power supply in the amp, then more caps on the power rails between the amp's internal PS and the outputs...those only charge when the amp is on.


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## NJPCRX (Jul 25, 2012)

maybe i'm an idiot, but why couldn't you just hook it to a good car battery charger and run a jumper wire to the remote terminal as well. Then u could adjust the amps. I have a 2/6/12 charger.


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## sqshoestring (Jun 19, 2007)

NJPCRX said:


> maybe i'm an idiot, but why couldn't you just hook it to a good car battery charger and run a jumper wire to the remote terminal as well. Then u could adjust the amps. I have a 2/6/12 charger.


You can but most car chargers don't have filters in them so the amp will buzz and sound terrible, in particular if you don't have a battery paralleled. A PS is the same thing otherwise, but with filters to take all the AC power out.


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