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Discharging capacitors,

cbkidd1

Well-Known Member
May 3, 2005
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I am sure this question has been asked before. I have a Yaesu ft-102 Transceiver. And was wondering what parts I would need to buy in order to build something to safely be able to discharge the high voltage capacitors? I am kind of getting tired of being electrocuted. Even after turning off and unplugging the transceiver and waiting for a few hours or even a day later hoping the caps have discharged. Only to find out the hard way that they are very much still charged. I have more than my share of scars. I appreciate the help.
 
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That clip and 10K resistor just might help save my life in the future. I really appreciate the help and info CK, 73,
 
"...tired of getting electrocuted." ??

If you get "electrocuted", you are dead. You can get shocked many times, like on a cold, dry day when you scuff your shoes on the carpet and then touch the kitchen sink to get a drink of water. Or touch a doorknob. This shock is high voltage but vanishingly small current. Therefore, no electrocution.

A capacitor, however, can retain enough electrical energy to stop a human heart. Those capacitors you describe SHOULD have resistors that bleed the current off, discharging the capacitor when the radio is "off". Those are called "bleeder" resistors, and they are there (or, again, SHOULD be there and not open-circuited) to protect you or anyone else doing troubleshooting and repair.

Check the manual to see what value the resistors should be. Locate them and disconnect one end and measure the resistance to see if they are within 5-10 percent of what Yaesu specified.
 
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Yes bleeders are VERY important. We always used either a "Jesus stick" or a large screwdriver to discharge the caps in transmitters just to make sure they were discharged before working on them. Never and issue with bleeders until that ONE time. I was just routinely going thru the motions when BANG!!. WTF!?? One of the power supply caps was still charged. Turns out that the 100 K ohm 250 watt bleeder had cracked near the base and open. That cap had 2600 volts in it and more than enough storage to have killed me. Lesson learned about trusting bleeders.
 
I know where you are coming from CK, I also got woke up by the caps and bleeders on my Henry 2K. Learned over it with the lid off and on with just a t-shirt on to close the window. And it burnt thew the shirt and melted it to my skin. It left me with two holes and third degree burns and months of healing, I am willing to bet it has happened to many others here on the forum. We just haven't heard about it.
 

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