Help sourcing replacement for this potentiometer?  - Page 1
Forum section: electronics / beginners

author: artvandalai
author_rank: Regular Contributor
timestamp: August 29, 2025, 12:06:22 pm
content: Any help sourcing a replacement potentiometer with these markings 110144 r1379009 from this hot plate stirrer? I was unable to find any info searching these numbers.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 29, 2025, 01:10:35 pm
content: Good Morning Artvandalai, If you would provide the make and model of the equipment that this pot is in, along with what the pot controls, would be helpful, along with some measurements. Also, there is probably a max. Ohm marked on the back, or other side..something like 5K or 10k. Why do you think the pot is bad? I would unsolder it and measure it's range with a DMM, also turn the pot through its entire range while observing the display, which would also tell you if it is a linear pot, or a logarithmic pot, and if there are any dead points. Also, a photo of the end of the shaft would help. Happy hunting

author: artvandalai
author_rank: Regular Contributor
timestamp: August 30, 2025, 11:11:42 am
content: Unfortunately theres no markings stating max ohms anywhere on the potentiometer. I confirmed the potentiometer is faulty by swapping the two potentiometers places after the heating element on the Corning 320 hot plate stirrer didnt turn on. On the back theres the brand CTS Type TCG 6amps 125v ac and a random number 12.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 30, 2025, 02:07:54 pm
content: Hmmmm....6 Amps is rather high for a potentiometer, so maybe it is a rheostat? It appears to be a common size to 'most' pots. Again, measurements of the body diameter, shaft diameter and length will help in the identification. Also, if you could wring it out with an ohmmeter, while turning the shaft completely in both directions, making note of the highest resistance each way between all possible connections, (draw a table of all possible combinations, and the Ohms values). If it is a rheostat that can handle 6 Amps, I would think it would be bigger than it appears. Perhaps another member has seen rheostats of this size?

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 30, 2025, 02:24:37 pm
content: Quote from: BILLPOD on August 30, 2025, 02:07:54 pmmaybe a potentiometer with the power switch. The 6A marking refers to the switch.

author: tooki
author_rank: Super Contributor
timestamp: August 30, 2025, 05:29:12 pm
content: Yeah, that’s definitely a switch!artvandalai, can you see whether that switch actually switches the mains power? While googling to try and find a manual or service manual (unsuccessfully), I came across this report about lab hot plate fires:https://www.osti.gov/servlets/purl/1506818It seems some models — among which the Corning models seem to be the most affected — are designed without adequate protection against a failed triac, resulting in uncontrolled heating even when “off”.The model you have does have reports of uncommanded heating, so I would only use it supervised.(The Heidolph units I have on my bench all the time at work, mostly for pot replacement (we have hundreds of them) use a physical power switch, a triac, a mechanical relay, and two PT1000 temperature sensors. If the two sensors’ measurements disagree by too much, the MCU disables heating. The other brand that is commonly used at work is IKA, which is designed similarly.)

author: artvandalai
author_rank: Regular Contributor
timestamp: September 01, 2025, 12:40:44 pm
content: Diameter 23.6x23.6mm shaft 6.3mm 42mm length. One potentiometer measures 522kohm and the faulty 46kohm. I cleaned the tracks with contact cleaner of both, but it still reads 46kohms. I installed it back on, and the heating element is still not working except when i swap the potentiometers places. This mean i need to replace it, or did i clean it wrong? This corning hot plate stirrer doesn't have an on off switch so it powers on straight when plugged in.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: September 01, 2025, 01:18:43 pm
content: Hmmmm....apparently the original IS a potentiometer, but that makes me curious what the 6 Amp marking means. Your pictures of the insides prove it can't handle that much current. Your Ohm readings are believable, but hook your probes to the center and either of the outside connectors and watch the Ohm meter to ensure it goes from zero, (or close to it), to the maximum as you turn the shaft from one limit to the other.I'm guessing the problem is not with the pot, but with the component it is controlling. It could be a power transistor or a triac, with a 6 amp rating. If you are comfortable working with mains voltage, you will need to probe around and see where you have mains voltage. Before that, though, again using your Ohm meter, follow the continuity from the center pin on the pot. Also follow the PCB traces.

author: tooki
author_rank: Super Contributor
timestamp: September 01, 2025, 08:13:59 pm
content: Quote from: BILLPOD on September 01, 2025, 01:18:43 pmThe photos VERY CLEARLY show the switch module on that pot, and what's printed on it are the SWITCH specs.

author: tooki
author_rank: Super Contributor
timestamp: September 01, 2025, 08:16:16 pm
content: Quote from: artvandalai on September 01, 2025, 12:40:44 pmWhat does the switch on that pot actually switch?

author: artvandalai
author_rank: Regular Contributor
timestamp: September 01, 2025, 08:51:51 pm
content: It turns on the hot plate only

author: mikerj
author_rank: Super Contributor
timestamp: September 01, 2025, 09:30:08 pm
content: Quote from: artvandalai on September 01, 2025, 12:40:44 pmThis is confusing, the photos show you measuring 46k between the ends of the carbon track (which seems quite reasonable for a nominal 47k pot), and the other picture shows you measuring 522k from the wiper to one end of the track. If this is the same potentiometer in both cases then there is a problem with the wiper connection, either not contacting the tracks, or the tracks have had the carbon/metalisation worn away. However your text above suggests you are measuring two different potentiometers?

author: tooki
author_rank: Super Contributor
timestamp: September 01, 2025, 10:47:58 pm
content: Quote from: artvandalai on September 01, 2025, 08:51:51 pmI assume that by that, you mean the heating function. (The whole device is the hotplate.)But you still aren’t understanding my question:what is the switch switching?Is it switching the mains input to the heating circuit? Or just some small signal within it? Or something else?

author: Andy Watson
author_rank: Super Contributor
timestamp: September 01, 2025, 10:54:31 pm
content: Pulling together the information elicited so far: You are looking for a 47k (or 500k) potentiometer with at least a single-pole switch of 6A capacity. 1/4 inch shaft, probably a 3/8 bush and something around 24mm diameter. Guessing by the application, it will be a linear pot.However, what is happening with the white wire in the photo - it appears to have broken away from a connection close to the edge of the PCB ?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: September 02, 2025, 01:22:31 pm
content: Golly-Gee,...the plot thickens. But I now see the switch attached to the back of the pot. A photo of the back of the board may give a clue to the purpose of the mysterious white wires.

author: tooki
author_rank: Super Contributor
timestamp: September 03, 2025, 05:26:21 pm
content: Quote from: BILLPOD on September 02, 2025, 01:22:31 pmA photo of the back was posted already, in reply #10.

author: artvandalai
author_rank: Regular Contributor
timestamp: September 07, 2025, 05:55:04 pm
content: Yes mains input to the heating circuit

author: artvandalai
author_rank: Regular Contributor
timestamp: September 07, 2025, 05:56:45 pm
content: I ripped the white wire trying to flip the board over to take pics.

author: artvandalai
author_rank: Regular Contributor
timestamp: September 07, 2025, 08:08:40 pm
content: Both potentiometers have different numbers on them. The faulty one is 6amps and the working one for the motor is 1amp.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: September 08, 2025, 12:41:24 pm
content: Quote from: tooki on September 03, 2025, 05:26:21 pmA photo of the back was posted already, in reply #10.OOPS, missed that:-. Thanks Tooki

author: artvandalai
author_rank: Regular Contributor
timestamp: September 13, 2025, 03:21:30 pm
content: Ive managed to fix the potentiometers switch by spraying the inside with contact cleaner and a bit of CRC 2-26 and working the switch on and off.