- Transistor ID - 5 Updates
| "ohg...@gmail.com" <ohger1s@gmail.com>: Jan 31 09:51AM -0800 On Tuesday, January 30, 2024 at 3:45:26 PM UTC-5, Mike H wrote: > Google search has not yielded any results. I do not have a schematic. The vac is powered by a 18V lithium battery. > In my testing I discovered if I connect a jumper between the left prong and the center prong, the vacuum seems to operate normally. If that is safe to do, I am happy to just solder a piece of wire between those prongs and call it a day.. > Mike That is a big honking high current Mosfet - make sure you use the original or something spec'd better if you know how to read a datasheet, and don't cheap out by buying on ebay or Alibaba. Digikey and Mouser carry those and you can be sure they're genuine, but there are several case styles for that series - some are surface mount and others have through-the-hole leads. Get the right one to fit the board. https://www.digikey.com/en/products/filter/transistors/fets-mosfets/single-fets-mosfets/278?s=N4IgTCBcDaIJYCcBmBGALABjSAugXyA Pick one that looks like it and double check the dimensions and spacings given on the datasheets to the one you need. |
| "Peter W." <peterwieck33@gmail.com>: Jan 31 10:11AM -0800 It's a TO3 case. The equivalency tool lists those that meet or exceed the original specifications. It is also still current, according to the tool. Peter Wieck Melrose Park, PA |
| Roger Hayter <roger@hayter.org>: Jan 31 08:24PM > I am happy to just solder a piece of wire between those prongs and call it a > day.. > Mike The transistor may be defective, or just lacking a signal on the gate to turn it on. Mosfets tend to be high resistance between all pins when tested in pairs. It would not be a good idea to permenently bypass it as it could cause damage to the motor, or battery if it has one. I suggest remove your short circuit and see if a voltage appears between the source and gate pins (see the datasheet others have drawn your attention to) when the vacuum is switched on. If not, maybe the mosfet isn't the primary problem. FWIW, they usually fail short circuit when the do fail, but then rusting is an unusual failure mode. -- Roger Hayter |
| whit3rd <whit3rd@gmail.com>: Jan 31 03:32PM -0800 On Tuesday, January 30, 2024 at 12:45:26 PM UTC-8, Mike H wrote: > Using my multi-meter as a continuity tester, I discovered a transistor that got rusty from the rain and does not appear to be functioning. > Can't seem to post a photo but it has 3 lines of text: > IRF1404 That's a MOSFET, it has very low input drive current requirement. It is different from bipolar transistors, doesn't have the same diode-check indications. > In my testing I discovered if I connect a jumper between the left prong and the center prong, the vacuum seems to operate normally. If that is safe to do, I am happy to just solder a piece of wire between those prongs and call it a day.. That doesn't mean that part is defective, it might just mean it isn't getting an ON command. Rust on a steel transistor case is unlikely to indicate a defect. Sometimes current leakage (due to dirt or moisture) goes away... in about a week, in a dry environment. Wait a while and re-test would be my recommendation. |
| ehsjr <ehsjr@verizon.net>: Jan 31 10:28PM -0500 On 1/30/2024 3:45 PM, Mike H wrote: Remove the jumper you added. Clean the circuit board with isopropyl alcohol and a tooth brush, scrubbing gently. Make sure it's dry before testing. The rust you see may be rust, but it might also be crud. The alcohol scrub will remove crud if it's there - but not rust. But in any event, electronics that you are trying to repair after it was left out in the rain should always be cleaned of any crud on the circuit board. Once the cleaning is done, if the problem is still there, you can proceed with some of the steps others have mentioned. Ed |
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