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Help finding this chip for a 1988 Ford Merkur Xr4Ti tachometer PCB

Alektron

Jan 14, 2018
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I'm trying to find a substitute chip like the one you see in the picture. This is for a 1988 Ford Merkur Xr4Ti tachometer PCB.

I searched all over the internet, but I can not locate one. Is anyone who can recognize this and might know what a good substitute would be for it? I would very much appreciate it.

Thank You.
1.jpg
 

debe

Oct 15, 2011
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Ive found quite often Tacho ICs are custom made, & its easier to get the tacho out of a wrecked car.
 

debe

Oct 15, 2011
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Seems to be plenty for sale on E bay. But there does not seem to be any data sheets available for this chip.
 

Alektron

Jan 14, 2018
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I found it on E-bay SN29736P, however this one has a "1" after the SN29736P.

Does that matter?

Thank you for everyone's help.
 

73's de Edd

Aug 21, 2015
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Sir Alektron . . . . .

How about taking my info below and comparing the foil side of the PCB wiring to ascertain if :
Pin 8 is going to the ground / plane negative of the board
Pin 5 and 6 are connected and going to the voltage supply for the chip.
Pin 2 has a cap going to ground
Pin 3 has a resistor and cap pair going to ground
Pin 4 connects to 7 and they are being the analog output of the unit which either
goes to other parts to feed your analog readout RPM meter . . . . or analog to digital converted as a RPM speed readout.

Pin 1 comes in from the engine compartment to feed either mag or photo-optic pulses into the chip.
I HIGHLY suspicion that this is your chip ad it was used a LOT for this application for years.
Your original unit is a Texas Instruments unit and they had a procedural of assigning new chips with an initial SN prefix until re released.
BUT National Semiconductor was already well esconced with this LM2907chip design initially.
Therefore, so much the more reason for a different designation.
Now 30 years later, TI has absorbed them . . .and just about everyone else.
If you can't read the board, show me a good closeup of the boards foil side.
And just think . . . . if you wanted a new FORD OEM version of that uit, you could be out $327.

TECHNO REFERENCING . . . .

upload_2018-3-9_3-37-50.png



73's de Edd
.....
 
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