I replaced my body CPU because it took a serious voltage hit. The replacement unit fixed the major issue but it wasn't perfect. The high beams and buzzer do not work among other smaller issues. So a visual inspection confirmed these bad components on the board. Note, the main board is an FC66-67-564 P/N (for a 91 Vert). The bad components are: Buzzer, C1, C2, C3, C4, C5, and C6. Refer to the attached photos for the details.

Based upon the values printed on each solid state component, Mouser Electronics had them in stock. Here are the values and part numbers for these components:

Comp - Mouser P/N - Manufacturer - Values
C1 - 667-EEA-GA1C470 - Panasonic - 16V, 47uf, 105*C
C2 - 667-EEA-GA1C100 - Panasonic - 16V, 10uf, 105*C (also for C4, C5, C6)
C3 - 667-ECE-A1AN221U - Panasonic - 10V, 220uf, 85*C
Q15 - 512-FJN4302RTA - Fairchild - See spec sheet link below (potential bad)
Buzzer - 497-TE162012-5 - DB Unlimited - 2.048kHz, 85dB, 115Ohm (Primary)
Buzzer - 539-PB1622PQ - Mallory Sonalert - 2.048kHz, 85dB, 140Ohm (Alternate)

The buzzer was difficult to research because it is stamped "RMX-12, STAR, 90' H". I found a couple of websites that helped identify the specifications however, it cannot be verified 100%. That is why I selected an alternate based upon external spec sheets found here:
http://datasheet.octopart.com/TMB05-...eet-514145.pdf (Goto Pg 16)
http://www.challengeelectronics.com/...-24P6.5LHR.pdf Challenge Electronics
http://www.mouser.com/ds/2/252/PB-1622PQ-26757.pdf Mallory Sonalert Specs
http://www.mouser.com/ds/2/683/TE162012-5-359434.pdf DB Unlimited Specs

Additionally, Q15 may need to be replaced because its legs looks dull. Perhaps the conformal coating is discolored. I wasn't able to get a good pic of it. The P/N on the transistor is "1202 0F" and had a difficult time verifying the specifications. In the event it must be replaced, I found this spec sheet for a RN1202 transistor manufactured by Toshiba:
TOSHIBA - datasheet pdf

The closest thing Mouser has for Q15 is this transistor from Fairchild:
http://www.mouser.com/ds/2/149/FJN3302R-889141.pdf

Finally, the 40-pin IC looks like it has some build up around 2 or 3 of its legs. See attached pic. I wasn't able to find a P/N online yet, but if anyone has any recommendations please respond. The P/N on the IC is D7507C(A), manufactured by NEC Japan.

I appeal to any electrical engineers who may have better recommendations on the buzzer, Q15, or the IC.

I will provide updates when the parts are replaced. Thanks for reading and any additional findings/input.

Btw if interested, this is why the original main board was replaced: https://www.rx7club.com/2nd-generati...arity-1102713/

 

https://www.rx7club.com/2nd-generati...er-fix-840197/

 

Jack, thanks for the link. Mod looks nice & clean too. I'll consider this modification as another path.

 

OK, so I found a datasheet for the 40-pin DIP IC chip. See the attached PDF. I wonder if any 7507 or 7508 IC would work? Now the harder part...find the chip for sale!

 

There are two versions of the main board for the FC66 CPU. One has the D7507C(A) IC chip, a big 40-pin chip that takes up the width of the board. The other main board has a smaller 42-pin IC chip, with part number D75P008CU. Does anyone have a good picture of the second board that clearly shows the part number? Mine is faded and could only be seen under magnification. See for yourself!



Conformal coating masks the part number on this 42-pin IC

 

Just a question, but if you are starting with a bad processor, and get a new one, how will you program the new one?

 

That's a great question! I am unaware if Mazda requested a unique program set from the chip manufacturer or if the chip has a default program set that Mazda used to suit. Similar to what an Intel i7 processor chip is to a mother board. An i7 is an i7 regardless of the device it is installed in.

 

It's a Math Processing Unit, it just takes inputs and gives you an ouput.

I wouldn't worry about that MPU, I'd worry about the gakk'd traces next to it.

 

Thanks, JJ. Yes, that board took a major power hit. The solder runs must be retraced and eyelets replaced.

 

I didn't read the datasheet, so I assumed it was a PIC or something, not a generic part.

 

AAron & JJ, After reading more of the spec sheets on the D7507 and D75P008 IC chips I found this info:
1. The uPD7507 and uPD7508 4-bit, single-chip CMOS microcomputers have the uPD7500 series architecture.

2. The uPD7507 and uPD7508 execute 92 instructions of the uPD7500 series A instruction set with a 5-usec instruction cycle time.

3. Differences between the features of the uPD7507 and uPD7508 are:4. Differences between the 75xxC & 75xxCU are:5. The devices in the uPD75008 family (reference to the 75P008CU chip) are available in standard or special quality grade devices Special grade devices have the symbol (A) embedded in the part number. A standard grade device will not bear any suffix. Therefore, a uPD75008CU is a standard grade and a uPD75008CU(A) is a special grade device. Special devices applications include automotive equipment.

6. The 75xxC and 75xxCU chips operate on a 400kHz clock.

7. The D75P008CU series IC has more capability in the following areas:8. I verified the part number of the 75P008CU IC chip, it has no (A) suffix.

9. It may appear that the D75P008CU IC will need a program set as it has a PROM. That will need to be verified.

Armed with this info, it would make sense to replace a suspect D7507C(A) with a D7507C(A) IC because of the memory limitations and the special application that the IC will operate in. The same logic applies to the D75P008CU IC on the newer board.

I attached both spec sheets here for faster reference.

 

I'm following this and look forward to seeing the results.

But...at what point do you say "Screw it!", grab an Atmel Mega, make a PCB that turns it into a generic I/O and then write some code?

 

Aaron,

I like your style but will defer that privilege of PCB making to you! LOL I am able to get the D7507C(A) chip but still looking for the D75P008CU chip.