Bleeder Resistors - Basic Principles

SAY WHAT?!

Bleeder resistors are usually very high values OHM wise (Usually between 500KOhms and 1 MegOhm), so they do not affect the way the unit works when power is on, but once power is removed, they allow a "Drain" path to ground, usually allowing them to remove the high voltage from the capacitors within say 10 to 30 seconds...

Also, very heavy power supplies of even 50 volts will usually have them installed, due to the shear size of current that can be drawn by an unwary finger ring or screwdriver from the reservoir capacitors if they are not "drained off" after power off....

Warning, certain models of CRT do not (always) drain the voltage off the back of the screen (I do not know why) and several Kilovolts can be "found" weeks after it was last connected to power!!

One other point, in the Cockney language of London and the surrounds, it could be that instead of using the "F***" word, a Cockney (some Australians too!) might swear at a resistor for example using the word "Bleeder" or "Stupid Bleeder". it may have very little to do with electronics in this case!!

Don't take all the fun out of the game!!!

It was fun pulling the HV anode with a pair of insulated pliers and watching it shoot that big streaming spark to ground... That and the X-rays that were given off by the HV rectifier tube inside the little, metal house!

CRT's, Is for economical reasons. Less bleeding less power required from the power supply. Don't forget that they DO bleed even when circuit is operational. and to possibly avoid HV arcing due to dust and dirt being accumulated on the resistor's body over time.

BTW: What do they say in central London, "Get the bleed out of here?" or "Get the bleeder...out of... " . Which one is more correct, (grammatically speaking.)

Wangito.

Also Hi-Capacity, Hi-V capacitors; specially GOOD-Insulation type [Glass, ceramic] even in Storage are shorted with a Spring-Wire & the shorting-link is removed after connected in Circuit to aviod charging by electrostatics so a risk.

Some hidden capacitors are formed inside components / Equipment:

e.g. CRTs all type intentionally or due to other functions needed.

The Screen-Coating on back of CRT forms a good capacitor for EHT supply also & holds charge long after the power-off.

Warning: Before taking the EHT-connector off the CRT discharge it with a grounded Test-lead by inserting the prod-tip ingressing below the rubber-pad which holds the EHT-connector to CRT.

WORKING PRINCIPLE :

Slowly Bleed the high-voltages to make it safe say in 10 minutes.

Fast bleeding HAMPERS EXPERIMENTS.