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

author: artvandalai
author_rank: Regular Contributor
timestamp: September 22, 2025, 10:11:17 pm
content: Can i get some help sourcing a replacement triac for a Corning hotplate stirrer? This specific model is showing as discontinued everywhere and im unsure what triacs would be compatible for this hotplate stirrer.

author: floobydust
author_rank: Super Contributor
timestamp: September 23, 2025, 12:55:28 am
content: Higher voltage parts like 600V or 800V replaced it.What you can do at Digi-Key is search the prefix "T435" and then "triacs" to see what's up.Look at using T435-600T.Important to know the tab is connected to A2/the middle pin, it is at hazardous live. This is a concern if it mounts to a heatsink, which then makes the heatsink live.I prefer to use isolated tab triacs. (but T435-600W obsolete). I think BTA06-600CW could work too.P.S- I had found info on the temperature controller IC for the heater, in the hot plate if that is what this triac controls. Or it's for the motor? I forgot.

author: artvandalai
author_rank: Regular Contributor
timestamp: September 23, 2025, 02:25:02 am
content: Yes this triac failed and kept blowing the fuses on this hotplate stirrer. It controls the heater.

author: Konkedout
author_rank: Frequent Contributor
timestamp: September 23, 2025, 04:07:01 am
content: I think that floobydust's advice on going to a higher voltage Triac is sound....butI STRONGLY SUSPECT THAT SOME OTHER FAULT IS BLOWING THE TRIAC. The triac ought to turn it on and off and maybe vary the speed. But even if the triac is shorted, I would normally expect the motor to turn full speed without blowing your fuse. I wonder whether your motor is shorted?

author: artvandalai
author_rank: Regular Contributor
timestamp: September 23, 2025, 04:28:32 am
content: These traces were peeling off when i checked the board. I repaired the traces with copper wire but by then the triac had already failed. For now i wont know if there's anything else wrong until i receive the replacement triacs.

author: Uunoctium
author_rank: Frequent Contributor
timestamp: September 23, 2025, 06:18:29 am
content: isolation failure of heater coil to earth?

author: floobydust
author_rank: Super Contributor
timestamp: September 23, 2025, 06:34:49 pm
content: Triacs are in series with their load. So a shorted triac means the heater is stuck on all the time, or the motor spinning at full speed. No fuse blowing or PCB traces melting.I think you're mixed up about this triac being for the heater. That should be the other one, that bolts to the heatsink. The heater is higher current.Maybe the wires are mixed up at the 4 pegs.I would say you have a ground fault, something shorting to the chassis ground.It could be the other triac- melted or the wrong type (non-insulated tab) was put in there. Check its part number and continuity to the tab should be open-circuit.Or the heating element has a short to its housing. Check with an ohmmeter from any heater wire to the chassis.

author: artvandalai
author_rank: Regular Contributor
timestamp: September 24, 2025, 05:40:24 pm
content: Are these bullet connectors ok to be soldered? They connect to these hot plate pins. They broke off on one of the hotplate stirrers, I tried crimping ferules to replace them since i couldn't find the correct size female bullet connector, but they dont secure well and fall off or feel loose since they are pretty short.

author: geggi1
author_rank: Frequent Contributor
timestamp: September 25, 2025, 08:30:27 pm
content: Looking at the PCB and seeing the triac without a heatsink tells me that it might have beeen overhested.Because you are looking at a replacement an go for a triac that will handle higher current and voltage. This will give you a more robust circuit.The important things is the trigging parameters.

author: artvandalai
author_rank: Regular Contributor
timestamp: October 17, 2025 07:41:15 am
content: Any advice on repairing the windings on this motor? I have MG Chemicals Clear Insulating Varnish and magnetic wire but Ive never rewinded a whole motor. This was the reason why the fuses kept blowing on this hot plate stirrer.

author: Zero999
author_rank: Super Contributor
timestamp: October 17, 2025 08:24:03 am
content: Quote from: artvandalai onYesterdayat 07:41:15 amNor have I.Are the bearings good?I recommend replacing the motor. It appears to be fairly standard shaded pole motor. Find one with the same dimensions and voltage/frequency and it will work.https://en.wikipedia.org/wiki/Shaded-pole_motor

author: mikerj
author_rank: Super Contributor
timestamp: October 17, 2025 12:48:59 pm
content: Rewinding it without removing the bobbin would be nearly impossible, but removing the bobbin means grinding off the rivets holding the laminations together and somehow removing the shading coils which typically have the ends of the coils welded together. You have little to lose but time by trying, but I suspect you'll end up having to source a suitable motor.

author: floobydust
author_rank: Super Contributor
timestamp: October 17, 2025 05:06:28 pm
content: Reach out to the manufacturerBay Motor Productsand ask them. It's likely an off the shelf fan motor.The white CSA/UL label could lead to the motor's part number.