wa2ise
05-30-2004, 10:17 PM
Back in the olden days (30 to 50 years ago) ham radio people used to scrounge parts to build transmitters and such. Usually by salvaging junked TV sets.
Today one can get a reasonable number of high voltage caps from salvaged computer monitors and switching power supplies. What I've done is to take junked computer monitors and strip out the circuit boards. Then throw out the CRT and cabinet. Pretty soon one has a well stocked "junk box". It takes about ten or more salvaged monitor boards before one has a decent chance to find a needed cap to unsolder for a recap job. There is a small risk that a cap failed to kill the monitor, but I haven't had that yet. Usually semiconductors in those are what die. Or someone gets a new system with monitor and tosses the old but still working old one. So I can usually recap a set without having to wait for mail order parts to arrive.
Generally monitors are more fruitful than PC switching power supplies so bear that in mind when faced with picking thru a big pile of junk.
Use ceramic caps in audio circuits (except in the hi-fi stereo amp), bypasses and non-critical RF and IF stage circuits. Avoid using ceramic caps in timing circuits (like vertical or horizontal osc circuits). Use mylar or such for those. Avoid the powerline bypass caps for coupling circuits. The "X2" marked ones. Those tend to be leaky. That doesn't bother the powerline service, but can muck up a tube's grid biasing.
The leads will be too short, so just clip out the old wax cap at its body and J hook solder the new ones in the TV set. If you want you could heat shrink the joints with that type of tubing.
Today one can get a reasonable number of high voltage caps from salvaged computer monitors and switching power supplies. What I've done is to take junked computer monitors and strip out the circuit boards. Then throw out the CRT and cabinet. Pretty soon one has a well stocked "junk box". It takes about ten or more salvaged monitor boards before one has a decent chance to find a needed cap to unsolder for a recap job. There is a small risk that a cap failed to kill the monitor, but I haven't had that yet. Usually semiconductors in those are what die. Or someone gets a new system with monitor and tosses the old but still working old one. So I can usually recap a set without having to wait for mail order parts to arrive.
Generally monitors are more fruitful than PC switching power supplies so bear that in mind when faced with picking thru a big pile of junk.
Use ceramic caps in audio circuits (except in the hi-fi stereo amp), bypasses and non-critical RF and IF stage circuits. Avoid using ceramic caps in timing circuits (like vertical or horizontal osc circuits). Use mylar or such for those. Avoid the powerline bypass caps for coupling circuits. The "X2" marked ones. Those tend to be leaky. That doesn't bother the powerline service, but can muck up a tube's grid biasing.
The leads will be too short, so just clip out the old wax cap at its body and J hook solder the new ones in the TV set. If you want you could heat shrink the joints with that type of tubing.