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I have a 6 year old top load washing machine which requires a TRIAC replacement for wash motor. The actual TRIAC that came with factory PCB board is NXP BT138X-800 and the one I am looking to replace with is BT139-800E. These are passivated, sensitive gate triacs and from the datasheets I can see some differences in characteristics specifically under IGT(gate trigger currents) and IL(Latching currents).

The wash motor is connected with a capacitor and then to a TRIAC on to the PCB board. Here is the tech specs for

Wash Motor 220-240V 50HZ 125W 1.28A 4P

Capacitor Rated on motor plate: 11uF/450VAC IPOO ClASS B

Currently using EPCOS LCAP 10uF +5/-0% with Inductor coil 110uH +/-7% Part No - B32350 (450VAC P0)

Note: EPCOS product sheet has mentioned 3 other TRIAC parts like ACST1235, ACST1035, BTA12-800CW but as of now I couldn't find them nearby.

Dee
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No, you can't because the BT138X-800 has an isolated tab. The BT139-800E has not.

The BT138X-800 is also selected as less sensitive by purpose, to prevent misfiring in a high electrical noise environment.

Janka
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  • Thanks for the reply. Yes, you're right I just double checked and there is no inter-connected metal tab for BT138X-800 compared to BT139-800E. I found another model BT138-600E https://www.mouser.com/datasheet/2/302/BT138-600E-211638.pdf I think its close except the voltage, do you think it will be a good replacement? – Dee Apr 28 '21 at 07:24
  • how can you tell BT138X-800 is less sensitive? I see BT139 says "Passivated, sensitive gate triacs" but that is just at the front page of the datasheet, might be marketing stuff again – Christianidis Vasileios Apr 28 '21 at 07:42
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    Hi @ChristianidisVasileios if you can check both the datasheets under features section there it is clearly mentioned "Less sensitive gate for improved noise immunity"(for BT138X) and "High sensitivity in all four quadrants."(for BT139). So I am not sure it is a marketing stuff or something else to be checked. However Janka is right on that point. – Dee Apr 28 '21 at 07:57
  • Oops sorry @Janka I forgot to mention BT138-600E also has a mounting base and not isolated. – Dee Apr 28 '21 at 08:37
  • @Dee: If you can't get your hands on that BT138X-800, you can use BTA12-800C as a replacement. Those are also very common in high-power household appliances. A beefier version is BTA16-800C. Both have an isolated tab. – Janka Apr 28 '21 at 09:49
  • @Janka Are you sure BTA12-800C and BTA16-800C have isolated tab? I tried to find the same info on this https://datasheetspdf.com/pdf-file/1395068/STMicroelectronics/BTA16-800CW/1 but couldn't. FYI, on my PCB there is small aluminium heat shrink plate mounted to which the BT138X base is screwed. Also unfortunately I couldn't find the ones you mentioned nearby I have to go to different place which is currently under lockdown. For now the local shop has got only BT139-800E and BT138-600E. – Dee Apr 28 '21 at 14:06
  • Yes. The BTA types have the circuit mounted isolated on the tab, so the tab itself can be copper. You can find that on page 13 of the datasheet. – Janka Apr 28 '21 at 14:09
  • Ok, thank you got it. I will try to get one of them and update here. – Dee Apr 28 '21 at 16:07
  • Hi @Janka, a quick update I managed to find a local seller who usually import components from RSComponents website. Here I found 3 parts in which two(BTA12, BTA16) of them were from your suggestions, third one is BT139X-800 which I believe is higher ampere version of BT138X. From the cost POV this BT139X-800 is cheaper and I am thinking to go with it. Adding to this unfortunately RS don't provide single pc and it has to be 5/10/Bulk packs where in reality I need just two. Before taking on it I would like to get your advice please if any.. thanks – Dee Apr 29 '21 at 07:30
  • @Janka You can find the details and datasheets in the below links https://export.rsdelivers.com/product/stmicroelectronics/bta12-800cwrg/stmicroelectronics-through-hole-3-pin-triac-800v/8290416 https://export.rsdelivers.com/product/stmicroelectronics/bta16-800cwrg/stmicroelectronics-through-hole-3-pin-triac-800v/7142596 https://export.rsdelivers.com/product/ween-semiconductors-co-ltd/bt139x-800127/ween-semiconductors-co-ltd-through-hole-3-pin/4842820 – Dee Apr 29 '21 at 07:32
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    BT139X-800 should do fine in your application. – Janka Apr 29 '21 at 12:54
  • Thank you @Janka :) I have placed the ordered and hope all goes well once replaced. If I face any issue I will post a new question :P – Dee Apr 29 '21 at 16:44