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Forum Index : Electronics : help identifying SMD chip

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CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 1727
Posted: 07:43am 28 Oct 2021
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Morning forum, you are all well I hope.

I need some help identifying the chip (372M) in the middle of this module below, it looks to be a TI beastie but I cannot find anything on it in all my searches. Any help you can give would be really groovy.



for the curious:

It is a bank sensor from a 2000 Harley FDX. Mate of mine has one and it keeps popping these. On the reverse is a V notch with a magnet that slides up and down, normal (upright) position leaves the magnet right over the sensor. Two outputs of that chip barely change but feed into pins 2 & 3 of that 372 so it is starting to look suspiciouly like an opAmp but the output to the tranny on the bottom comes from pin 7, not 6 as i would have expected. There is an 8K2 resistor from the output pin (bottom) to ground and the ECU provides a gentle 5V so it looks like one half of a potential divider. The transistor shorts the output to 0V.

Placing an 8K2 resistor across the pins to the ECU kills the engine - to be expected if the magnet is in its normal place and the output of the 372 is on to the base of the tranny - shorting the output to 0V. But... place a wire link to ground leaves the engine warning light on (bike starts etc), so if it doesn't like a steady state, I am starting to suspect a data stream. I plan to scope the output when I get the module (but it's failed so that may not be trustworthy). In the meantime a whole bucket of insight is gained from knowing what that chip is.
 
poida

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Joined: 02/02/2017
Location: Australia
Posts: 1082
Posted: 08:14am 28 Oct 2021
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I think it's a TI opamp
this one

pin 4 is ground and looks right
pin 8 is Vcc and looks right

feedback from 2IN+ to 2OUT, maybe hysteresis type
amplifier, with a threshold
wronger than a phone book full of wrong phone numbers
 
CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 1727
Posted: 08:29am 28 Oct 2021
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fantastic job @poida!

that fits well, the output to the base of the transistor (1M) is coming from pin 7 so everything fits now.

Now to determine why a short from the output to the ground leaves the EW light on.

Cheers for your help, really appreciated
 
poida

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Joined: 02/02/2017
Location: Australia
Posts: 1082
Posted: 09:00am 28 Oct 2021
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my payment is only redeemable in beer..
wronger than a phone book full of wrong phone numbers
 
CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 1727
Posted: 12:00pm 28 Oct 2021
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beer vouchers ($) ok?  
Edited 2021-10-28 22:01 by CaptainBoing
 
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