Transistor ID

[Mike H]

I am trying to repair my Milwaukee M18 vacuum; model 0880-20. I left it outside, it rained, and the rest is history.

I have only a very rudimentary knowledge of electronics from building Heathkits 45 years ago. That being said I am not afraid...

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

IOR P446D

TONH

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

[Arie de Muijnck]

Google for IRF1404 turns up the datasheet and suppliers:
https://www.google.com/search?q=IRF1404
--> https://www.infineon.com/cms/en/product/power/mosfet/n-channel/irf1404/

Arie

[legg]

Best not to jumper out anything to do with battery supply
or charging. You don'y indicate whether battery charge
is present or maintained.

Replace bad parts first.

Check charging status first.

RL

[Miguel Gimenez]

If you short the gate to the drain the MOSFET becomes a current source
and will burn in a while. The problem is in whatever part drives the
gate (the left prong).

--
Saludos
Miguel Gimenez

[Peter W.]

Equivalents are, per Alltransistors.com:

Type Mat Struct Pc Vcb Vce Veb Ic Tj Ft Cc Hfe Pack
________________________________________________________________________________________
2N5630 Si NPN 200 120 120 7 20 200 1 500 20 TO3
2N6322 Si NPN 200 300 200 30 200 40 TO3
2N6323 Si NPN 200 300 200 30 200 40 TO3
2N6340X Si NPN 200 140 25 40 30 TO3
2N6341X Si NPN 200 150 25 40 30 TO3
2N6686 Si NPN 200 260 160 8 25 200 20 25 TO3

IRF1404 Si NPN 200 120 120 7 20 200 500 20 TO3

I hope the table comes through.

Peter Wieck
Melrose Park, PA

[Arie de Muijnck]

Since when can you just replace an N-channel MOSFet with an NPN transistor?
Especially since the OP has 'rudimentary knowledge' and no schematics.

Arie

[ohg...@gmail.com]

On Tuesday, January 30, 2024 at 3:45:26 PM UTC-5, Mike H wrote:

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.]

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.

[Roger Hayter]

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]

On Tuesday, January 30, 2024 at 12:45:26 PM UTC-8, Mike H wrote:
> I am trying to repair my Milwaukee M18 vacuum; model 0880-20. I left it outside, it rained, and the rest is history.
>
> I have only a very rudimentary knowledge of electronics from building Heathkits 45 years ago. That being said I am not afraid...
>
> 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]

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

[Mike H]

I'll give the IPA and toothbrush trick a shot, follow the recommendations above, and report back....

Thanks again