Warning: session_start() [function.session-start]: open(/home/content/10/6202210/tmp/sess_qm9kj634k5lt72vgrnt4hkc204, O_RDWR) failed: No such file or directory (2) in /home/content/10/6202210/html/includes/functions.php on line 2

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/content/10/6202210/html/includes/functions.php:2) in /home/content/10/6202210/html/includes/functions.php on line 2

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/content/10/6202210/html/includes/functions.php:2) in /home/content/10/6202210/html/includes/functions.php on line 2
High Voltage Power Supplies
 
  Home Buying Guide Articles News br Reference Books Contact Us
High Voltage Info    
 
Home
Buying Guide
Articles
HV News
Reference
Books
Applications
Contact Us
Add Your Company to Buying Guide
NEWSLETTER
» Ask a Technical Question
» Free Product Selection Service
» Register for Free High Voltage Newsletter
» Read High Voltage Stories
» Add Your Company to Buying Guide
"We are your high voltage reference.  Please contact us with all your high voltage questions."
-- Fred Wright
 
 
High Voltage Stories »
(Email us your stories!)


Getting Zapped While Isolated From Ground?

This TV (Electrohome/Mitsubishi Model 69CK03, Chassis UM2-C-10R) would power up and immediately blow the fuse on the “cold” side of the circuit board. On the “hot” side (power supply) after changing the bridge rectifier, everything checks normal. I get 125 volts using a 100W light bulb at the (removed) collector of the HV transistor. I changed the flyback. The fuse no longer blows, but the TV goes into shutdown. I removed the CRT circuit board, then pressed the power button and got zapped by the high voltage. No longer taking a chance with my finger on the power button, I used a remote to turn on the TV. There’s a cap between the two 120V line inputs (.01mfd 250V). A piece of plastic surrounds part of the circuit board. When powering up the TV, arcing occurs from one end of the cap to the plastic. I checked the plastic. There’s nothing under it. This is arcing from one of the line inputs. I removed the anode from the TV and measured the high voltage. My meter went up to 40K. I disconnected the TV before it got any higher. No arcing occured with the anode disconnected.

I think that the high voltage is crossing over from the “cold” side to the “hot” side of the board. Or from the anode to the ground straps on the TV tube, to all grounds on the board.

The point is that I have been servicing TV’s for over 20 years. This was the first time I ever got zapped by high voltage by only touching the power button on the circuit board, and touching nothing else. I was also sitting on a wooden chair with my feet off the ground. How many people ever got zapped by pushing a plastic power button? And, as mentioned before, I had checked the power supply for excessive voltage output. I know all the dangers of servicing TV’s, but this was really unexpected, and I wonder to how many people did this ever happen to?

Back to HV story listing

 

 

Warning: Unknown: open(/home/content/10/6202210/tmp/sess_qm9kj634k5lt72vgrnt4hkc204, O_RDWR) failed: No such file or directory (2) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct () in Unknown on line 0