Author Topic: Bad wall switch (WS467)  (Read 5192 times)

bkenobi

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Bad wall switch (WS467)
« on: November 05, 2013, 08:25:17 AM »
I've got a couple wall switches that stopped functioning correctly.  In the past, I'd just order new ones and move on.  However, since the supply may dry up eventually, I figured I'd take a look at them and see if there's something that can be done to fix them.

I don't recall what was wrong with the first one as it failed a couple years back.  The other one just flaked out last week.  The second one would not turn off with local button or remotely via PLC command.  It wouldn't even turn off when the slider switch was toggled, only when power was cut completely.  When power was restored, the switch continued to function incorrectly.

So, I replaced it and no have the faulty one disassembled.  First question is, once taken apart, how does one reassemble it?  The stupid slider switch metal tab  is balanced on one side and the spring and wheels on the other.  There doesn't seem to be a good way to get it back together.  I looked at:

http://www.idobartana.com/hakb/modifying_wall_switch.htm

But, have not tried either method 1 or 2 yet (will later on).

Second, that page doesn't seem to talk about anything that matches my symptoms.  Other than playing around with it in a disassembled state (checking for obvious faults, etc), any opinions on what to look for?  I'm just looking at this from an educational stand point right now, not necessarily at putting it back in service.

Brian H

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Re: Bad wall switch (WS467)
« Reply #1 on: November 05, 2013, 10:29:26 AM »
Maybe two problems.
The safety slider switch breaks the Line Input and if it didn't work. Was probably broken in the On state.
The On no matter what you do. Sounds like the Triac used to turn it On and Off along with dimming. Is shorted and can't be controlled.

I took one of those apart and never figured out the puzzle of reassembly.
« Last Edit: November 05, 2013, 10:31:00 AM by Brian H »

bkenobi

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Re: Bad wall switch (WS467)
« Reply #2 on: November 05, 2013, 10:34:34 AM »
I did a bit more reading and saw that the triac could fail.  Looks like RadioShack used to carry a replacement, but that's no longer the case.  Anyone have a source for a replacement?  I found a guide that detailed a test for function of the triac, so that might be a good thing to look at.

I also found a link from the page I posted earlier with a detailed reassembly procedure, which sounds pretty reasonable.

Brian H

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Re: Bad wall switch (WS467)
« Reply #3 on: November 05, 2013, 11:02:01 AM »
One of my old archived WS467 schematics indicated it was a BTA10-400C
Specifications for the RS 267-1000
http://support.radioshack.com/support_supplies/doc37/37468.htm

Mouser has a BTA10-400CRG that I believe is the ROHS version.
http://www.mouser.com/ProductDetail/STMicroelectronics/BTA10-400CRG/?qs=ue4Ab%252bqZy1bF3BIs4Z3ygw%3d%3d
There is a specifications sheet link on the Mouser sales page if you care to compare them.

I also saw a NTE5645 mentioned on the site you linked to.

bkenobi

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Re: Bad wall switch (WS467)
« Reply #4 on: November 06, 2013, 07:59:43 PM »
I removed the triac so I could test the unit.  Although I found a guide that suggests a way to test the module, I'm not getting similar results, so I don't know if it's good or not.

If I measure resistence:

A1-A2: open
A1-G:  67ohm
A2-G:  67ohm

I did not notice any difference if I switched the direction of the leads.  I tried to measure from A1 to A2 and then touch A2 to G, but didn't notice a difference.  Perhaps my test was conducted wrong, but does what I've done so far say if the triac is good/bad already?

Brian H

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Re: Bad wall switch (WS467)
« Reply #5 on: November 07, 2013, 04:42:42 AM »
I will try and measure one and post my findings.

Brian H

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Re: Bad wall switch (WS467)
« Reply #6 on: November 07, 2013, 01:13:08 PM »
OK I found a BTA10-400C I had removed from a soft start LM465.
It was from the famous half bright when full On problem. I feel it was just the soft start electronics where not triggering it properly.
A1-A2 Open with red or black on either terminal.
A1-G 53 Ohms with red or black on either terminal
A2-G Open with red or black on either terminal.

I also tried a few in circuit of two LM465s.
Same results except A2-G was around 750 KOhms with red or black on either terminal. I think the 750 KOhms was reading through the circuitry.

bkenobi

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Re: Bad wall switch (WS467)
« Reply #7 on: November 07, 2013, 05:23:36 PM »
Interesting.  Looks like A2-G should be open and it's not on mine.  I have one other test that I found that should answer for sure.  If I hook up the module in series with a light bulb and power it, it should be off.  If I connect the gate to A1 (or A2 depending on the chip), it will power on the bulb and should stay on when the power is removed from the gate.  I have to find the schematic to verify I hook it up correctly, but it looks like it probably won't work correctly based on your readings anyway.  Thanks for checking!

dave w

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Re: Bad wall switch (WS467)
« Reply #8 on: November 08, 2013, 06:28:55 AM »
FWIW
I don't know if this is your problem, but triacs shorting to "full on" when the incandescent bulb "blows" at turn on, is pretty common in (older) X10 lamp and switch modules.  The "Soft-On" feature helps to reduce that problem to an extent. Trying to find a replacement triac with a 600-800 PIV might help ( I think the actual PIV in the X10 triacs was only 500V). Also the X10 lamp module (and likely the wall switch) is not real critical about the triac it is driving. I have subbed 25 Amp triacs to drive studio lighting - with additional heat sinking - and the module gates the heavier triac to saturation just fine). So a 600V 5 Amp or greater  w/ isolated tab should work fine.
http://www.radioshack.com/product/index.jsp?productId=13125139
http://www.allelectronics.com/make-a-store/item/MAC16M/MAC16M-TRIAC-16A-600V/1.html
This after shave makes me look fat.

bkenobi

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Re: Bad wall switch (WS467)
« Reply #9 on: November 08, 2013, 08:12:58 PM »
This is an older non-soft start switch and it did fail at the same time as a halogen bulb failed.  It sounds like that's the issue.

I'll try replacing the traic and see if that gets these going again.

bkenobi

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Re: Bad wall switch (WS467)
« Reply #10 on: November 25, 2013, 09:40:44 PM »
The slow boat finally arrived today.  After swapping the triacs, both switches seem to function correctly with local control of a 40W incandescent bulb.  Thanks for the suggestions!
« Last Edit: November 26, 2013, 08:39:17 AM by bkenobi »

Brian H

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Re: Bad wall switch (WS467)
« Reply #11 on: November 26, 2013, 03:10:10 AM »
Good to read the switches where fixed.

 

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