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N8TCQ
01-01-2011, 12:04 AM
I have a Swan 500C and 2 power supplies. The last power supply burned up on me while the radio was just sitting there on receive. Itwas fine, I walked away for about 15 minutes and when I returned the radio was off. Smelled burned wiring so I investigated and found some of the wires in the power supply melted, a couple of diodes on the high voltage side literally burned apart. It also melted some of the wires in the main cord from the supply to the transceiver. Nothing in the radio is burned. I have a few ideas, but like to collect opinions from other people. Could the output tubes have shorted internally and caused this "melt-down"? The other supply I have exibits the same problems. I later found out it was on this radio originally. Thanks in advance. Happy New Year all !!!

W9GB
01-02-2011, 04:19 AM
Swan 117xc Power Connector a Hazard to Swan Equipment Owners
You Tube Video !!
http://www.youtube.com/watch?v=wL4N4eZGSaI

A replacement board was offered by Stephen Judd, KB7BGS
http://www.angelfire.com/nb/swantrader/

Rainbow Canyon ARC
http://www.rcarc.info/newsletter/aug_2010.pdf

Complete replacement board, a Double Sided printed circuit to upgrade your Swan 117-X and XC power supply.
It has the following features:

Has 7 pages of instructions, pictorials, and schematic to assemble the board and replace the old Swan board.

+ Replaces all components except the power transformer and filter choke.
+ HV capacitors of 330 uF @ 400v. versus the original 100 uF @ 350v.
+ The extra capacitance will stabilize the high and medium voltage as the current varies during SSB or CW operation.
+ Current surge protection for those expensive to replace tubes to prolong their life.
+ Custom, double sided, PC board with plated through holes from commercial vendor.
+ Selection for the normal 800+ DC voltage for the final, or around 600 volts if you are driving a linear or just want to extend the life of those finals.
+ Diodes with a 1.5 amp rating, versus the original 3/4 amp Swan diodes.
+ Bleeder resistors on all DC output voltages to discharge capacitors on shut down, unlike the original.
+ Terminal block for easy connection of the transceiver cable.

Contact me for any further feedback or infromation
eMail me at: swanradios@yahoo.com

73, Glad to help Stephen, KB7BGS

There is a return warranty if you are not completly satisfied just send the item back in the same box and
packing material that you received it in within 3 days and money will be returned.

N8TCQ
01-31-2011, 12:53 AM
I rebuilt the supply. Put in heavier diodes and made up a new harness from the power supply to the transceiver and it's working well. Had to do some maintainence on the rig itself, found a few resistors way out of spec. Before doing that the rig wouldn't pop back to receive unless you keyed it when changing from band to band, now it's working perfectly. it even seems to have a better receive, better sensitivity and more volume thru the speaker. I post these other problems and the cures just in case anybody else has similar problems.

AD4DQ
01-31-2011, 02:40 AM
I went through a similar situation with a Heathkit HP-23.... the radio would only put out 50 watts no matter what.....
after tuning the radio over and over I looked at the power supply, 2 of the 4 big electrolytics were shorted out..... so
rebuild the PS and she tuned to 100 watts no problem. I replaced the diodes too, the resistors were all good. Great job on rebuilding your power supply. I picked up a PSU-3A for my Swan 250. Seems to be ok.... I will keep an eye on that too.

W8JI
01-31-2011, 09:00 AM
I have a Swan 500C and 2 power supplies. The last power supply burned up on me while the radio was just sitting there on receive. Itwas fine, I walked away for about 15 minutes and when I returned the radio was off. Smelled burned wiring so I investigated and found some of the wires in the power supply melted, a couple of diodes on the high voltage side literally burned apart. It also melted some of the wires in the main cord from the supply to the transceiver. Nothing in the radio is burned. I have a few ideas, but like to collect opinions from other people. Could the output tubes have shorted internally and caused this "melt-down"? The other supply I have exibits the same problems. I later found out it was on this radio originally. Thanks in advance. Happy New Year all !!!

Just curious. What kind and type of fuse do you have???

AD4DQ
01-31-2011, 01:11 PM
Just curious. What kind and type of fuse do you have???

Just a 35 amp :D

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