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Author Topic: TS940S Power Switch Replacement  (Read 2526 times)
N6AB
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« on: May 19, 2013, 07:57:14 PM »

After 28 years, my Kenwood TS940S power switch finally bit the dust.  It won't stay latched in the on position anymore.  I did a Google search for S40-2418-05, which is the Kenwood part number for the switch (used in both the TS930 and TS940), and in all cases the result was 'no longer available'.  The only thing that showed promise was searching for used switches on eBay, which were salvaged from old radios, although who knows how long those will last?  I figure that I probably put about 10,000 cycles on the original switch.  Now I just wish I had stocked up on the Kenwood part while they were still available.  The original switch was rated for 5A at 250VAC.

While searching the Digi-Key catalog, I found a switch which seems to be a reasonably close replacement, at only $2.42 each.  The Digi-Key part number is EG1018-ND, which is an E-Switch P227EE2B20A.  It's actually a DPDT switch, which is not a problem since I just won't use 2 of the pins.  The physical size of the replacement switch is slightly smaller, although the 3mm threaded holes and spacing are identical, and everything fits the TS940 just fine.  Since there are electrical terminals on both sides of the switch, I did have to cut the pins on the sheet metal facing side of the switch with wire cutters, and filed them down to be flush with the package, similar to what was done on the original switch by the vendor.  After completing the switch replacement, everything works fine!  The new switch is rated for 7A at 125VAC, or 4A at 250VAC, and for 6000 electrical cycles at the maximum rated load.  Since the TS940 fuse is 6A at 120VAC, and maximum current is < 4.25A during transmit, we are within the switch rating. The only question is how long will the new switch last?  I am hoping it will last twice the rated number of electrical cycles, since I am using it at substantially less than the rated load.  If not, I've got three spares at $2.42 each. 

Has anyone found any better options?  If you stocked up on the original Kenwood parts, they're probably worth a fortune now ...
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KE3WD
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« Reply #1 on: May 20, 2013, 04:47:29 AM »

Look on the switch itself for a manufacturer's part number.  Then source the manufacturer (NOT Kenwood) for possible replacement. 

Given the era of the '940 and the manufacturer of same, it is very likely that the power switch was supplied by a japanese company called, "ALPS" - Bing should be able to bring up Alps corp., but a Bing of the part number on the switch itself may bring up more definitive information. 

ALPS replacement switches are carried by quite a few electronics catalog houses, DigiKey, Mouser, etc. as well as MCM Electronics, all of which have online catalogs with Search Engines. 

The key to the Search Engine is likely to go much better with the actual mfr and part number off of the switch itself rather than the Kenwood part number, which is "inhouse" reference and now, of course, no longer supported for most parts of a rig that age, but don't assume that to be the actual case until after contacting Kenwood Parts, as they might still have a switch in stock that fits the rig, you never know unless and until you try.


73
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N6AB
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« Reply #2 on: May 20, 2013, 06:59:08 AM »

Great advice!  The original switch says it is an ALPS SDS 3P.  Some are advertised for sale using the internet search engine, although one particular website shows a picture of the switch with the pins cut off on the wrong side, so one has to be careful before ordering.  It looks like Kenwood specified that the vendor cut off the pins on a particular side of the switch, otherwise the pins could short out against the adjacent sheet metal part.  I've got one ALPS switch on order as a future replacement backup.

For any other owners replacing the power switch, be sure to label the wires before removing and carefully solder them to the correct pins.  Otherwise, the 120VAC and +28VDC lines could be crossed.  I wouldn't want to see a TS940S go up in smoke because the wires were connected to the wrong pins!

Thanks and 73's,

John
« Last Edit: May 20, 2013, 07:37:17 AM by N6AB » Logged
N4NYY
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« Reply #3 on: May 20, 2013, 07:05:22 AM »

http://www.ebay.com/itm/ALPS-SDS-3-P-Nos-Sds3p-/111071003139

http://www.bluestar-online.com/SW_12_DPST_5_amp_250V_p/sw-12%20dpst%205%20amp%20250v.htm

Good luck! Seems there are plenty available.
« Last Edit: May 20, 2013, 07:08:08 AM by N4NYY » Logged
N6AB
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« Reply #4 on: May 20, 2013, 07:22:51 AM »

That's the one!  I ordered one from that eBay auction.  I almost ordered one from bluestar, but the website image shows the pins cut on the wrong side of the switch, so the terminals are without holes.  It might still work, though, if you rotate the part 180 degrees and use heat shrink around the soldered pins.  Either way, the price is right, and more important, the parts are still available.

73's
« Last Edit: May 20, 2013, 08:00:50 AM by N6AB » Logged
N4NYY
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« Reply #5 on: May 20, 2013, 07:59:18 AM »

The Blue Star site may just be a wrong pic. Typically, if it is the same part number, it is the same switch. I cannot tell you how often they get the picture wrong. Especially on appliance and lawnmower parts. But no matter. Just glad you have options.
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KA5IPF
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« Reply #6 on: May 20, 2013, 09:55:31 AM »

The OEM switch has been discontinued by Alps, found that out when I needed some. I do have them for sale though.

Clif
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WI8P
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« Reply #7 on: May 22, 2013, 10:24:02 AM »

Blue Star part is only $7, but they want $11 for shipping whereas the eBay part is $10, but shipping is only $4!   Shocked
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KA5IPF
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« Reply #8 on: May 23, 2013, 07:29:47 AM »

I charge $13.50 shipped CONUS

Clif
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