False rumor -> GPA to stop repairs of Altec products.

[elitopus]

Ok that answers my question. So basically you hit the button and it charges up as much as it can. Once the magnet is saturated it just stops taking a charge.

How do you know when discharging a magnet that you aren’t doing it so much that it puts a reverse charge on it? Or is that not how you discharge?

 

[BillWojo]

I would imagine that you reverse the polarity of the coil and use an educated guess as to how much power to dump into the coil. It's probably something that comes with experience.

BillWojo

 

[bowtie427ss]

How do you know when discharging a magnet that you aren’t doing it so much that it puts a reverse charge on it?

You measure with the gauss meter.

I'd imagine there's a certain field strength below which is considered neutral.

I would imagine that you reverse the polarity of the coil and use an educated guess as to how much power to dump into the coil. It's probably something that comes with experience.

BillWojo

This is how i understand the process to work. Probably not the healthiest thing to spend a lot of time close to.

Worth the time to let the pics load here for the bank of discharge capacitors alone, you might have to refresh a couple times: http://www.audioheritage.org/vbulle...netizing-fixture&p=61484&viewfull=1#post61484

33,000mfd @400vdc, what could go wrong?

 

[elitopus]

So it’s easy when you have the VC gap open, but how about when a driver comes in for a remag but not a recone? I do agree it probably comes from experience

 

[Pio1980]

Why neutralize the slug before recharging?

 

[bowtie427ss]

Why neutralize the slug before recharging?

Outside of repairing/re-centering damaged motor assemblies, I can only guess.

Perhaps a partially charged magnet is somehow resistive to taking a complete charge.

So it’s easy when you have the VC gap open, but how about when a driver comes in for a remag but not a recone?

Again, i can only hazard guesses.

But, i suspect "re-mag only" jobs represent a very small percentage of jobs that will pass thru any magnetizer, and in those events they're going to be drivers that the tech is intimately familiar with to the extent that they know which parameters tend to slide, and in which direction on a low charge.

By T/S analysis if the moving assembly is in proper order, and the basic electrical parameters test OK but other parameters such as Fs are out of range, the experienced tech will know when to attribute that to a weakened magnet.

 

[elitopus]

That makes sense