I'm trying to identify this part to make a repair to a lamp fixture. I replaced the BT134 and the results are still the same and the lamp fixture is not working properly. I narrowed it down to the potentiometer. In all my years of being in this trade, I've never came across the name / package of a potentiometer like this. I'll include images of the pinout which is unique to me. You'll see in the pictures that the pot has two pins that were soldered to the PCB. The action this pot preforms is something that I'm not sure how to look up. The pot has a "clicking" which means the pot is open / the light is off. Once you turn the pot and it clicks, the lamp turns on and as the pot is twisted through it's variable resistance, the lamp dims / brightens.

Again, I'm just trying to identify the type of pot this is so I can order a new one. I tried filtering on Mousers but I can determine the filters to use to find the part.

 

It's just a regular 500K potentiometer with one of the terminals cut off. It is used as a variable resistor.

 

It's just a regular 500K potentiometer with one of the terminals cut off. It is used as a variable resistor.

Are you sure those 2 pins on the back mean nothing? The PCB shows that where those 2 pins are soldered, they are connected to traces. I will say that the DMM indicates that those two pins on the back connect to nothing on the pot so I think your correct on it just being a regular 500k pot.

Do you by chance know what to look up when looking for potentiometer that acts also as a switch as well? If I replace it with just a regular 500k, it won't act as also a switch to turn the fixture completely off.

Thanks for the help!

 

Lamp dimmers are not complex circuits. Usually, the first thing to go is the triac. I have never had to replace any other component.



(Substitute 110-120 VAC for 220 VAC in countries where it applies.)

What do you mean by the switch is not working? Is the lamp fully ON or fully OFF?
Usually, the triac fails in a shorted mode, i.e. the lamp is fully ON.
Yesterday, I fixed a dimmer circuit where the triac blew out the plastic package. In this case, the lamp was fully OFF.

If the variable resistor measures open circuit then the lamp will not turn on. In most cases, you don't need an ON/OFF switch because the dimmer itself is capable of turning the lamp off.

 

I replaced the BT134 triac. Once the pot reaches it's minimum resistance, the lamp turns to full brightness but the pot at any other resistance value doesn't allow it to turn on at all.

The clicky noise I'm referring to is the pot. It seems like the pot acts as a switch as well and the clicky noise is the contacts inside making a connection. The pot when turning doesn't feel smooth at all when turning and I don't even hear the contacts inside anymore when the wiper reaches that point. I'm just trying to figure out how I make sure the pot I'm looking for as this switch feature.

Again, the pot seems to also act as switch to turn the lamp off as well on dim the light. There is no off / on switch on the fixture besides the variable knob from the pot.

 

I see no ON/OFF contacts on that pot.

You should not be hearing any clicks when the pot is turned.
Here are three 500kΩ pots I have picked out for you.

https://www.jameco.com/z/3386T-1-LS...K-Ohms-1-2-Watt-1-Turn-Thru-Hole_2161414.html

https://www.jameco.com/z/RV09AF-40-...-50mW-20-20mm-Long-Knurled-Shaft_2272231.html

https://www.jameco.com/z/RV09AF-40-...Vertical-Knurled-Shaft_2272207.html?CID=MERCH

 

I replaced the BT134 triac. Once the pot reaches it's minimum resistance, the lamp turns to full brightness but the pot at any other resistance value doesn't allow it to turn on at all.

The clicky noise I'm referring to is the pot. It seems like the pot acts as a switch as well and the clicky noise is the contacts inside making a connection. The pot when turning doesn't feel smooth at all when turning and I don't even hear the contacts inside anymore when the wiper reaches that point. I'm just trying to figure out how I make sure the pot I'm looking for as this switch feature.

Again, the pot seems to also act as switch to turn the lamp off as well on dim the light. There is no off / on switch on the fixture besides the variable knob from the pot.

The clicking is caused by the broken track inside the potentiometer.

 

The clicking is caused by the broken track inside the potentiometer.

Keith,

I'm going to post a video here if possible when the guy sends it to me. The light fixture does not have an on/off switch. So how does the light turn off then? The guy explained to me that once the pot is turned all the way over, it makes a "click" noise and the lamp turns off. He has the other lamp fixture on the other side of his bed.

Everyone here is saying that it's just a normal potentimeter but I can confirm that it is not. Once the pot hits a certain point, the pot opens like a switch to turn the light off.

I just need help trying to find this kind of replacement. Again, I'll try to post a video of the working one to show you how the pot works.

 

Sure you can buy a pot with a switch. Show us a photo of the one that needs replacing.