[mythtv-users] OT - Life without MythTV

[Brian Wood]

On Feb 25, 2008, at 1:30 PM, Bill Omer wrote:

>
> Other than leaving the set unplugged for several hours, is there  
> another
> way?  I've heard that some caps that just wont discharge unless you
> short them.

The usual way is to use a "chicken stick", sometimes known as a "Jesus  
stick".  This is basically an alligator clip on one end of a well- 
insulated wire with a high-voltage type probe at the other end.  
Technically it should have a resistor to limit current flow but a lot  
of them don't have this. You slip the probe under the rubber cap of  
the connector on the CRT.

If you pop the HV connector of the CRT (carefully), then touch the  
metal part to the chassis before working on the xfrmr it usually  
discharges any residual HV.

To be honest, most capacitors used in today's consumer units are so  
crappy they don't hold a charge for long.

>
>
>>
>> You really should measure the high voltage after a flyback
>> replacement, but I suspect you do not have a voltmeter designed for
>> upwards of 20K volts.
>>
>
> I've read 50kV.  Deadly ... easily.   By far not a safe project IMHO.

Usually around 26-33 Kv. Not  generally "deadly" as there is not  
enough current there to kill you except under unusual circumstances,  
but it hurts like blazes, I know :-(

Now the power supplies in High-power TV transmitters are another  
story. That's why we called them "Jesus sticks", when you shorted a  
cap that somehow didn't get discharged by the interlocks and saw the  
arc you would often say "Jesus, that could have been me!".

One reason for checking the voltage is that you can get X-Ray emission  
if the voltage is too high, but most sets these days have overvoltage  
sensing and shutdown circuitry.

Just be careful if you don't have experience with such things.

beww