On Wed, 25 Sep 2013 07:57:30 -0500, Ignoramus4074
wrote:

On 2013-09-24, Gunner Asch wrote:
On Tue, 24 Sep 2013 22:05:25 -0500, Ignoramus20545
wrote:

As part of a scrap deal, I purchased a nonworking Anca Fastgrind CNC
tool and cutter grinder, a coolant tank with numerous pumps and
motorized screen, and a Boyar Schultz 612 Deluxe surface grinder with
a dust collector and an electromagnetic chuck. The total cost was
$150 for everything, I had to remove.

Anyway, supposedly, the only thing wrong with the Boyar-Schultz
grinder is that "the EM chuck does not work". I tried to diagnose it a
bit today. I found out that the chuck itself works, if I apply DC
current to it from a power supply, it becomes magnetic. So, my
thinking goes, the power supply is bad. If so, what alternatives do I
have? Would any 90v DC power supply work, if it can provide enough
current? Is there anything special about the magnet's power supply?

i

They typically use a standard bridge rectifier..available at Radio
Shack (or use to be) for about $5.

Its a very simply 110vt input...through a bridge rectifier and out to
the magnet. Some..some have a transformer inside to bring 220/440
down to the proper voltage.

Mine has an additional transformer...or rather a different transformer
with voltage taps that are selectible through a rotary switch. Switch
Pos 1= 25 volts, 3 is 50 volts and so on.

Some..some have a second switch or switch position..it shoots 90-110
AC through the magnet to demagnitize the part AND the magnet.

These fancier mag power supplies typically have a 90 vot power supply
that provides clean DC, rather than 60 hz half wave DC.

Most of the standard version..are very very simple inside. Simply
check if you are getting power in, power to the rectifier, and DC out
of the rectifier and power to the output of the power supply. Some
use a relay instead of switching the entire power supply off and on..
So check to make sure power is going to the relay, power off/on to the
relay coil (from external switch) and 90vts dc coming out of the
relay.

Ive fixed a ****load of them over the years and its typically a bad
wire, a bad switch..then a bad rectifier..and then a bad relay.

If your power supply is old..and it has a selenium rectifier..and its
bad...and it is likely to be..simply replace it with the Rat Shack
bridge rectifier.

OK, great, seems like an easy enough job for me! Thanks a lot!

Jervelcom!

"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state.
Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic
problem of Socialism, until it becomes obvious that nothing has been changed but the name.
The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more
than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy,
and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)