Basic Discharge Q: Disconnected all connectors?

Altan

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I read somewhere that when discharging a monitor you should disconnect the game from the AC power and disconnect the monitor itself from all connectors (such as from the main PCB).

Is this the recommended approach?

... Altan
 
I shut everything off, but don't necessarily remove video connectors or the power connector before discharging. I've found some chassis will actually give off a bit of static sound if you remove the neckboard and yoke connectors before discharging, so i just leave everything hooked up but shut off, discharge, then start unplugging things, making sure to discharge again before pulling the anode wire...
 
Thanks guys.

Another basic question... If you did the discharge while not connected to an AC ground... where does the discharge from the monitor go?

(If this question shows I don't understand something, no worries about pointing it out! But even if we treat the monitor as a big cap, the stored energy needs to go somewhere... I don't see where it goes if you just connect it to an ungrounded chassis)
 
Another basic question... If you did the discharge while not connected to an AC ground... where does the discharge from the monitor go?

The picture tube acts like a big capacitor. You're draining it by shorting it out. The energy is lost as heat. Just like when you short out a transistor radio battery with a screwdriver. You'll drain it, and it'll heat up the screwdriver. The tube only holds it's charge for a fraction of a second though.

-Ian
 
The picture tube acts like a big capacitor. You're draining it by shorting it out. The energy is lost as heat. Just like when you short out a transistor radio battery with a screwdriver. You'll drain it, and it'll heat up the screwdriver. The tube only holds it's charge for a fraction of a second though.

-Ian

Thanks... Makes sense.

Finally, it appears that you don't need a resistor when discharging a raster monitor, but it is (highly?) recommended when discharging a B&W vector. According to the B&W vector faq, a 1 Meg ohm 3W is appropriate.

I suppose you don't get a nice "pop" when using the resistor, is that right? Makes it harder to know you were successful :(
 
Correct. The only time you really should use a resistor is on black and white sets - the inline diode is easily damaged. Color monitors have diodes integrated into the flyback, and aren't sensitive to that.

You can use a resistor on all monitors if you like, but you don't get that reassuring *POP* noise.

-Ian
 
You're draining it by shorting it out. The energy is lost as heat. You'll drain it, and it'll heat up the screwdriver.

Not exactly, by my understanding. Electrical charge is conserved. The purpose of discharging isn't disappating energy as heat. Before discharging, there is a surplus of electrons on one side of the CRT, and a deficit on the other. Connecting them together allows the charge to equalize. Not a big deal, practically, but conceptually the answer to "where do the electrons go" when you discharge is "to the other side of the CRT."
 
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