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eHam Forums => Elmers => Topic started by: KB7QND on April 02, 2011, 06:43:21 AM



Title: IC-718 and PS-55
Post by: KB7QND on April 02, 2011, 06:43:21 AM
Anyone know if an old Icom PS-55 power supply is compatible with the new Icom 718?

I checked the manuals and 4 of the 6 pins match up.

Its the last two pins on the 718 that I'm not sure if they are used to switch the supply on/off as there is no on/off switch on the PS-55.


Title: RE: IC-718 and PS-55
Post by: N4IAG on April 02, 2011, 02:56:47 PM
I had an ic-718 and ps-15 which also did not have an on/off switch. The 718 doesn't have the ability to switch on the ps. What I did was install a toggle switch on the front of the ps, hooking it to those extra 2 wires and everything worked well by turning on the ps manually.


Title: RE: IC-718 and PS-55
Post by: KB7QND on April 04, 2011, 05:35:46 PM
Thanks for the reply.

I haven't opened mine up yet to look inside.  

I'm assuming you just connected a switch between the positive and negative wires leading to those two pins on the Molex connector?  Some how I'm thinking it wasn't as easy as that.  But I'm assuming the open circuit occurs at the Molex connector and therefore bridging those two pins with a switch will close the circuit.

Do you happen to remember the current rating for the switch you used?

I just saw on another website that you should bridge across Pins 3 and 6.  Well, not bridge and keep live current flowing all the time, but use a switch across the two.  Is that what you did?


Title: RE: IC-718 and PS-55
Post by: W4VR on April 05, 2011, 07:11:04 AM
I use a PS-25 with my 718.  I also have a PS-26 but the pins don't match.  I bought a cable with a 6 pin connector on one end and a 4 pin on the other end to make it work....just plugs in to the existing cable.


Title: RE: IC-718 and PS-55
Post by: N4IAG on April 05, 2011, 09:00:39 AM
Thanks for the reply.

I haven't opened mine up yet to look inside.  

I'm assuming you just connected a switch between the positive and negative wires leading to those two pins on the Molex connector?  Some how I'm thinking it wasn't as easy as that.  But I'm assuming the open circuit occurs at the Molex connector and therefore bridging those two pins with a switch will close the circuit.

Do you happen to remember the current rating for the switch you used?

I just saw on another website that you should bridge across Pins 3 and 6.  Well, not bridge and keep live current flowing all the time, but use a switch across the two.  Is that what you did?


HI, yes this sounds the same as what you're talking about. All you have to do is open the PS and clip the 2 wires used for the radio switch (the ones going to pins 5 & 6) inside towards the back, where they go to the cord (leave enough to reconnect again if needed) splice if necessary and connect to toggle switch. I used a heavy duty toggle switch, because I had one, but the switch wires were pretty small gauge as I recall and the switch I used was overkill. All you are doing is providing a means to short the 2 wires together, thus turning on the PS. The PS-55 will now be useable with many 100w class rigs. Hope this helps.


Title: RE: IC-718 and PS-55
Post by: KB7QND on April 08, 2011, 05:27:10 PM
IC718 arrived.  I plugged the PS-55 directly into the 718 and surprisingly the power supply turned on.  Apparently Icom had already bridged Pins 3 and 6 within the 718; which means the that the supply was always on....which is a waste of electricity and unneeded heat in the shack.

I found that you could switch this supply two different ways. 

Look for the yellow and blue wires (approximately 16 gauge in size, could be a little smaller) coming from the Molex connector.

1.  For the IC718 where Pins 3 and 6 are bridged within the radio causing a closed circuit all the time, you need to cut either the blue or the yellow wire.  It doesn't matter which one.  Place a switch at that cut to open and close the circuit. 

2.  For other projects that are not using Pins 3 and 6 there will be an open circuit at Pins 3 and 6; say for example you're only going to use this supply to run a couple of cooling fans.    Do not cut any wires, simply bridge a switch across the blue and yellow wire to close and open the circuit. 

I did modification #2 which worked perfectly to turn the supply off and on; until I plugged it into the IC718 which had Pins 3 and 6 bridged.  So I had to undo Mod #2 and complete Mod #1.

I had an automotive 12V 20A rocker switch, which is overkill, but it came with dash mounting hardware.  I was able to use an existing chassis screw to mount this to the top of the power supply.

Hopefully this helps anyone using a PS-55 for other things other than the IC-735 for which it was designed.