FD Speedometer-Odometer Circuit Board - Components Only
 

Good afternoon, fellow members!

This thread is intended to be used in conjunction with this link: just got done figuring out how to fix an FD odometer

Examine the photos from my Speedometer & Odometer circuit board for your reference. If anyone is interested in a specific close-up or may need a part number check from this board then please respond below. Additionally, I may need your help in identifying some part numbers from the IC chips. There are some I cannot read because of the conformal coating applied to the circuit card. Furthermore, no research was performed to cross-reference these components. Other members are more than happy to contribute their findings to this thread.

NOTE: This circuit board comes from a US Spec 1994 FD.


https://cimg0.ibsrv.net/gimg/www.rx7...4776301b42.jpg

Speedometer Face + Circuit Board

https://cimg6.ibsrv.net/gimg/www.rx7...3475c03853.jpg

R10 is a 200Ω resistor<br/>D4 is a diode with no legible markings.

https://cimg7.ibsrv.net/gimg/www.rx7...9edc56173c.jpg

Side view of speedometer with VR (blue Phillips head). VR is the speedometer adjustment potentiometer.

https://cimg0.ibsrv.net/gimg/www.rx7...f1f75d7fe1.jpg

Bottom 1/3 of circuit board backside. Note the surface mounted components.

https://cimg1.ibsrv.net/gimg/www.rx7...25a776196f.jpg

Middle 1/3 of circuit board backside.

https://cimg2.ibsrv.net/gimg/www.rx7...f008ed7de6.jpg

Top 1/3 of circuit board backside.

https://cimg5.ibsrv.net/gimg/www.rx7...bd166b8e5b.jpg

IC1 P/N*: (Stamped Motorola) Line1: 74HC14A Line2: 343BW
*Please help properly ID this P/N.

https://cimg7.ibsrv.net/gimg/www.rx7...3eb6ea2750.jpg

IC3 P/N: Line 1: B39AD Line 2: 93C56EN

https://cimg4.ibsrv.net/gimg/www.rx7...78bc5e934c.jpg

IC4 P/N*: (Stamped Texas Instruments) Line 1: 12903 Line 2: 1ABA (last A is boxed).
*Please help ID correct part number for IC4.

https://cimg3.ibsrv.net/gimg/www.rx7...8b3b4a120f.jpg

IC5 P/N: Line 1: D75108GF(A) 915 Line 2: NEC Japan Line 3: 9235PX702

https://cimg2.ibsrv.net/gimg/www.rx7...b24d990dc1.jpg

IC6 P/N: Line 1: AN8363UBK Line 2: Japan 41.2

https://cimg7.ibsrv.net/gimg/www.rx7...bd7b757fc1.jpg

C3 was previously replaced with this blue Panasonic capacitor.

https://cimg8.ibsrv.net/gimg/www.rx7...120151e93a.jpg

Different angle of C3 and surrounding components.

https://cimg1.ibsrv.net/gimg/www.rx7...2c0518c0ee.jpg

The HUGE Zener diode is ZD6. It's P/N is either 3NB PZ627, PZ627 3NB, or just PZ627.

Photos not shown for IC2 and IC7. IC2 is located to the right of C3 and IC7 is underneath the Odometer Digital Display.

Part numbers for both are as follows:
IC2 P/N:
TA78DS
05P 3H

IC7 P/N:
OKI Japan
M6544
2322201V

Again, any help to properly identify the part numbers for IC1 and IC4 is appreciated. As seen in these photos, the two IC chips are covered in conformal coating and is difficult to read with a magnifying lens.

https://cimg3.ibsrv.net/gimg/www.rx7...59418aa405.jpg

Mechanical Pencil points at IC2.

https://cimg4.ibsrv.net/gimg/www.rx7...4798de51dc.jpg

Mechanical Pencil points at IC7. IC7 is underneath the Odometer Digital Display.
Old solder flux is the reason for all the brown stains on the circuit board.

Thanks for posting this up! You're doing some good work here!

The 93c56en chip is the odometer chip, my thread on the odometer and making JDM clusters work covers that. It's an EEPROM that stores the pulses from the speed sensor.

Dale

Thanks, Dale! And thank you for identifying IC3 as the Odometer chip. Is this the link you refer to?
https://www.rx7club.com/3rd-generati...o-mph-1015964/

Do you have any other part IDs? If anyone else has more input on proper part numbers or DigiKey part numbers then feel free to respond.

Cheers,
George

This looks like a probable match for ZD6, a high-power 27V zener diode by Sanken Electric Co. Datasheet link here: http://datasheet.datasheetarchive.co...051.1489734055

Are there any parts that fail often or get damaged often? I've skimmed through the other tacho and speedo threads, but fortunately haven't had any trouble with mine so I was not reading closely.

Thanks for the research, Scotty!

The good news is that the part number is the same as stenciled on the diode, PZ627. The bad news is that part cannot be purchased, it is no longer manufactured. The likelihood of that power zener diode blowing up is relatively small. The most failed item that I've seen on the speedometer board is C3, and/or a few other capacitors.

I'd also like to add something from Dale's speedometer conversion (see link in post #10). Another member found a suitable part number for VR (Variable Resistor) used to calibrate the speedometer.

In short, here's the skinny:
VR: 200kΩ, trimmer potentiometer, Digikey P/N: 3306K-204-ND, manufacturer P/N: 3306K-1-204
ZD6: P/N: PZ627, Power Zener diode, manufactured by Sanken, availability unknown/no longer available

Cheers,
George

Speedometer Components List
 

***UPDATE: This information is out of date but remains for historical tracking purposes. Please refer to the most recent post that reflects the most up-to-date and accurate part number lists.***

Good evening, fellow members!

While replacing a few capacitors today, I did a little more digging on the speedometer circuit board. Here is a list of components with their part numbers or values. This list is intended to be a better place to extract part numbers instead of sifting through photos. Use DigiKey, Mouser, or Google to cross-reference these parts.

NOTE: Quite a few part numbers were either illegible, partially visible, or not stenciled on the part.

If I made any errors on this list or if anyone can add to this list with part numbers or missing values then please post your findings.

Capacitors (Values shown)(Temp on all Caps: 105*C)
C1: 10uF, 50V, DigiKey P/N: 493-1890-ND
C2: 47uF, 25V, DigiKey P/N: P5539-ND
C3: 1000uF, 6.3V, DigiKey P/N: P10199-ND
C4: 1uF, 50V, DigiKey P/N: 565-1332-ND
C5: *Surface mount device on backside of board*
C6: 1uF, 50V, DigiKey P/N: 565-1332-ND
C7: *Surface mount device on backside of board*
C8: *Surface mount device on backside of board*
C9: R33 (line 1) BP (line 2), 50V, *P/N search suggests 33uF*
C10: *Surface mount device on backside of board*
C11: 2.2uF, 50V, DigiKey P/N: P13462-ND
C12: 10uF, 50V, DigiKey P/N: 493-1890-ND
C13: 1uF, 50V, DigiKey P/N: 565-1332-ND
C14: *Surface mount device on backside of board*
C15: 153J50 (line 1) NIS F (line 2), *Need capacitance & voltage values*
C16: 2.2, 50V, *Need capacitance value, could be uF or pF*
C17: 1, 50V, *Need capacitance value, could be uF or pF*

Resistors:
R10: 20Ω, 5% Tolerance (stamped 20ΩJ)
R18: 20kΩ, 5% Tolerance
R25: 10kΩ, 5% Tolerance
VR: 200kΩ, Digikey P/N: 3306K-204-ND, manufacturer P/N: 3306K-1-204

Integrated Circuits:
IC1: 744C14A
IC2: TA78DS
IC3: 93C56EN
IC4: L2903 *not 12903 from the photos*
IC5: D75108GF(A)
IC6: AN8363UBK
IC7: M6544

Power Transistors:
TR1: D1922 (line 1), E (under last 2)
TR2: D1922 (line 1), E (under last 2)
TR3: G8 (device is very small, next to ZD6)
TR4: B1217
TR5: C458 (line 1), D (line 2), 3D1 (line 3)
TR6: A143 (line 1), X.SZ (line 2)
TR7: C144 (line 1), ESZ (line 2)
TR8: C144 (line 1), ESZ (line 2)
TR9: C1214 (line 1), C (under last 4)

Diode Arrays:
DA1: P209 (line 1), S. X (line 2)
DA2: DA218

Resistor Arrays:
RA1: *Not Installed*
RA2: E10kΩ39, *Implies 10kΩ resistance)

Crystal:
XTAL: 4190A (line 1), 3N2 (line 2)

Diodes:
D1: *No markings*
D2: *No markings*
D3: *No markings*
D4: *No markings*
D5: *No markings*

Zener Diodes:
ZD1: *Illegible*
ZD2: *Illegible*
ZD3: *Illegible*
ZD4: 7 *Partial*
ZD5: 5 *Partial*
ZD6: PZ627
ZD7: *Illegible*
ZD8: 3 *Partial*
ZD9: 3 *Partial*
ZD10: 30 *Partial*

I agree PZ627 is unlikely to fail, I wouldn't bother looking for an equivalent replacement unless someone actually needed it.

The part suggested for C3 looks good to me, although if there is space for a slightly taller capacitor this one can tolerate higher voltage: digikey PN P10225-ND

Scotty,

Thank you for sharing the alternate P/N for C3.

I offer a word of caution when replacing capacitors rated at higher voltages. Think of that higher voltage rating in a capacitor like a fuse - when the fuse fails it will do so at its rating. Replacing a 10A fuse with a 15A fuse in a circuit will lead to damaged components because failure occurred at a higher value.

If a replacement capacitor is rated for 10V where the original is rated for 6.3V then further damage may occur to the surrounding circuit should a failure occur. More importantly, a capacitor's charge & discharge rate could be negatively affected when a higher voltage rating is used. Keep in mind that capacitors oppose any change in voltage. That could equate to unforeseen circuit malfunctions.

Cheers,
George

Updated List - Added ZD4
 

***UPDATE: This information is out of date but remains for historical tracking purposes. Please refer to the most recent post that reflects the most up-to-date and accurate part number lists.***

Here is an updated list that added the part number for ZD4. Thanks to TravAZ who posted his results on Post 192 & 195 at https://www.rx7club.com/3rd-generati...-599220/page8/.

Capacitors (Values shown)(Temp on all Caps: 105*C)
C1: 10uF, 50V, DigiKey P/N: 493-1890-ND
C2: 47uF, 25V, DigiKey P/N: P5539-ND
C3: 1000uF, 6.3V, DigiKey P/N: P10199-ND
C4: 1uF, 50V, DigiKey P/N: 565-1332-ND
C5: *Surface mount device on backside of board*
C6: 1uF, 50V, DigiKey P/N: 565-1332-ND
C7: *Surface mount device on backside of board*
C8: *Surface mount device on backside of board*
C9: R33 (line 1) BP (line 2), 50V, *P/N search suggests 33uF*
C10: *Surface mount device on backside of board*
C11: 2.2uF, 50V, DigiKey P/N: P13462-ND
C12: 10uF, 50V, DigiKey P/N: 493-1890-ND
C13: 1uF, 50V, DigiKey P/N: 565-1332-ND
C14: *Surface mount device on backside of board*
C15: 153J50 (line 1) NIS F (line 2), *Need capacitance & voltage values*
C16: 2.2, 50V, *Need capacitance value, could be uF or pF*
C17: 1, 50V, *Need capacitance value, could be uF or pF*

Resistors:
R10: 20Ω, 5% Tolerance (stamped 20ΩJ)
R18: 20kΩ, 5% Tolerance
R25: 10kΩ, 5% Tolerance
VR: 200kΩ, Digikey P/N: 3306K-204-ND, manufacturer P/N: 3306K-1-204

Integrated Circuits:
IC1: 744C14A
IC2: TA78DS
IC3: 93C56EN
IC4: L2903 *not 12903 from the photos*
IC5: D75108GF(A)
IC6: AN8363UBK
IC7: M6544

Power Transistors:
TR1: D1922 (line 1), E (under last 2)
TR2: D1922 (line 1), E (under last 2)
TR3: G8 (device is very small, next to ZD6)
TR4: B1217
TR5: C458 (line 1), D (line 2), 3D1 (line 3)
TR6: A143 (line 1), X.SZ (line 2)
TR7: C144 (line 1), ESZ (line 2)
TR8: C144 (line 1), ESZ (line 2)
TR9: C1214 (line 1), C (under last 4)

Diode Arrays:
DA1: P209 (line 1), S. X (line 2)
DA2: DA218

Resistor Arrays:
RA1: *Not Installed*
RA2: E10kΩ39, *Implies 10kΩ resistance)

Crystal:
XTAL: 4190A (line 1), 3N2 (line 2)

Diodes:
D1: *No markings*
D2: *No markings*
D3: *No markings*
D4: *No markings*
D5: *No markings*

Zener Diodes:
ZD1: *Illegible*
ZD2: *Illegible*
ZD3: *Illegible*
ZD4: 1N4742A, DigiKey P/N: 1N4742AFSCT-ND, Radio Shack P/N: 2760563
ZD5: 5 *Partial*
ZD6: PZ627
ZD7: *Illegible*
ZD8: 3 *Partial*
ZD9: 3 *Partial*
ZD10: 30 *Partial*

I can't find any values for DA218 or anything to cross reference it. Anyone happen to know?

Here is a link for the datasheet on DA1: ROHM - datasheet pdf

But DA2 (DA218) is a bit harder to find. This is the closest datasheet that I found: Datasheet Archive

The 2nd link actually shows data for P209 and DA218. When the link opens, click the 3rd PDF link.

FD Kid, Did DA2 have a melt down? I hope these links help you. Please let me know if you find a suitable replacement for DA2.

Cheers,
George

Sorry but I do not agree based on what the USAF taught me. So I looked it up and here it is. Remember a capacitor only stores energy.

The voltage rating on a capacitor is the maximum amount of voltage that a capacitor can safely be exposed to and can store.

Remember that capacitors are storage devices. The main thing you need to know about capacitors is that they store X charge at X voltage; meaning, they hold a certain size charge (1µF, 100µF, 1000µF, etc.) at a certain voltage (10V, 25V, 50V, etc.). So when choosing a capacitor you just need to know what size charge you want and at which voltage.

Why does a capacitor come in different voltage ratings? Because you may need different voltages for a circuit depending on what circuit you're dealing with. Remember, capacitors supply voltage to a circuit just like a battery does. The only difference is a capacitor discharges its voltage much quicker than a battery, but it's the same concept in how they both supply voltage to a circuit. A circuit designer wouldn't just use any voltage for a circuit but a specific voltage which is needed for the circuit. For one circuit, 12 volts may be needed. A capacitor with a 12V rating or higher would be used in this case. In another, 50 volts may be needed. A capacitor with a 50V rating or higher would be used. This is why capacitors come in different voltage ratings, so that they can supply circuits with different voltages, fitting the power (voltage) needs of the circuit.

Take note that a capacitor's voltage rating is not the voltage that the capacitor will charge up to, but only the maximum amount of voltage that a capacitor should be exposed to and can store safely. For the capacitor to charge up to the desired voltage, the circuit designer must design the circuit specifically for the capacitor to charge up to that voltage. A capacitor may have a 50-volt rating but it will not charge up to 50 volts unless it is fed 50 volts from a DC power source. The voltage rating is only the maximum voltage that a capacitor should be exposed to, not the voltage that the capacitor will charge up to. A capacitor will only charge to a specific voltage level if fed that level of voltage from a DC power source.

Keep in mind that a good rule for choosing the voltage ratings for capacitors is not to choose the exact voltage rating that the power supply will supply it. It is normally recommended to give a good amount of room when choosing the voltage rating of a capacitor. Meaning, if you want a capacitor to hold 25 volts, don't choose exactly a 25 volt-rated capacitor. Leave some room for a safety margin just in case the power supply voltage ever increased due to any reasons. If you measured the voltage of a 9V battery supply, you would notice that it reads above 9 volts when it's new and has full life. If you used an exact 9-volt rated capacitor, it would be exposed to a higher voltage than the maximum specified voltage (the voltage rating). Usually, in a case such as this, it shouldn't be a problem, but nevertheless, it's a good safety margin and engineering practice to do this. You can't really go wrong choosing a higher voltage-rated capacitor than the voltage that the power supply will supply it, but you can definitely go wrong choosing a lower voltage-rated capacitor than the voltage that it will be exposed to. If you charge up a capacitor with a lower voltage rating than the voltage that the power supply will supply it, you risk the chance of the capacitor exploding and becoming defective and unusable. So don't expose a capacitor to a higher voltage than its voltage rating. The voltage rating is the maximum voltage that a capacitor is meant to be exposed to and can store. Some say a good engineering practice is to choose a capacitor that has double the voltage rating than the power supply voltage you will use to charge it. So if a capacitor is going to be exposed to 25 volts, to be on the safe side, it's best to use a 50 volt-rated capacitor.

Also, note that the voltage rating of a capacitor is also referred to at times as the working voltage or maximum working voltage (of the capacitor). So when seeing the (maximum) working voltage specification on a datasheet, this value refers to the maximum continuous voltage that a capacitor can withstand without becoming damaged.

I agree with Chuck (cewrx7r1). I don't work with aerospace-grade equipment, but I have used 16V capacitors on 5V supply lines and 25V capacitors on 12V supply lines without problems. In an automotive application, it's not uncommon for the 12V supply voltage to spike above 40V for a very short time after the ignition key is turned off; research 'load dump' or 'inductive flyback' if you want to learn more about it. A 16V capacitor will live a short life under those conditions, 25V will probably survive, and 50V capacitor should be good but the package size will be quite a bit larger. The 5V line is less likely to see excess voltage, unless there is a short in the harness or a person accidentally connects 12V to the 5V line by wiring a sensor incorrectly. This would be the reason to use a 16V capacitor on a 5V supply line that might connect to the outside world, if packaging space and budget allows. For the inside of an RX-7 odometer it might be overkill... if 12V gets on the 5V line there are probably other components beside the capacitors to worry about.

Chuck & Scotty,

You make excellent points and took a lot of time researching the function of a capacitor in an electrical circuit. I was attempting to reinforce the practice of replacing a bad component with a new one that matches the same values. Fortunately, these capacitors are easily sourced and there is no need to increase the safe working voltage of a capacitor because of convenience. Additionally, no schematics exist for the speedometer circuit board so it would be difficult to logically evaluate the benefits of altering some component values.

As Chuck stated, the voltage rating on a capacitor is the maximum amount of voltage that a capacitor should be exposed to and can store safely. However, don't assume that a higher voltage capacitor has the required performance; a capacitor of a specific value has a specific job. It's replacement should meet that specific job. Could there be unforeseen changes in the circuit, especially with RC charge/discharge times?

I do have one other opinion to offer: There may be other members who are not comfortable soldering components or may lack electrical troubleshooting skills. Please be careful when repairing the speedometer circuit board and/or the instrument cluster. There are tachometer quick fixes on the forum that may inadvertently cause more problems, such as the speedometer board blowing up. If there is a need to run new wires outside of the flex print to the tach then perhaps a different solution may be considered. Soldering is not too complex but it is tedious and requires a steady hand. If a member has low confidence then seek help from someone whose been there before. There are many members who would be happy to help, myself included.

In the end we contribute to the preservation of our cars through threads like this and other how-to's. Again, Chuck & Scotty thank you for providing those detailed points about capacitors!

Cheers,
George

P.S. Members, your help is still needed to identify the remaining unidentified components.

moved to correct thread.

fzkhan7, thank you for posting photos of your board. It should really go here: just got done figuring out how to fix an FD odometer for advise.

This thread is only intended for parts identification. Consider it an illustrated parts breakdown that lists component values and/or part numbers.

In the mean time, look at Post #243 for suggestions.

Cheers,
George

Updated List - Added TR5, TR7, & TR8
 

***UPDATE: This information is out of date but remains for historical tracking purposes. Please refer to the most recent post that reflects the most up-to-date and accurate part number lists.***

After reading some old posts, this update adds P/Ns for TR7 and TR8. Thanks to OP - Post #130 and OP Post #109!

Capacitors (Values shown)(Temp on all Caps: 105*C)
C1: 10uF, 50V, DigiKey P/N: 493-1890-ND
C2: 47uF, 25V, DigiKey P/N: P5539-ND
C3: 1000uF, 6.3V, DigiKey P/N: P10199-ND
C4: 1uF, 50V, DigiKey P/N: 565-1332-ND
C5: *Surface mount device on backside of board*
C6: 1uF, 50V, DigiKey P/N: 565-1332-ND
C7: *Surface mount device on backside of board*
C8: *Surface mount device on backside of board*
C9: R33 (line 1) BP (line 2), 50V, *P/N search suggests 33uF*
C10: *Surface mount device on backside of board*
C11: 2.2uF, 50V, DigiKey P/N: P13462-ND
C12: 10uF, 50V, DigiKey P/N: 493-1890-ND
C13: 1uF, 50V, DigiKey P/N: 565-1332-ND
C14: *Surface mount device on backside of board*
C15: 153J50 (line 1) NIS F (line 2), *Need capacitance & voltage values*
C16: 2.2, 50V, *Need capacitance value, could be uF or pF*
C17: 1, 50V, *Need capacitance value, could be uF or pF*

Resistors:
R10: 20Ω, 5% Tolerance (stamped 20ΩJ)
R18: 20kΩ, 5% Tolerance
R25: 10kΩ, 5% Tolerance
VR: 200kΩ, Digikey P/N: 3306K-204-ND, manufacturer P/N: 3306K-1-204

Integrated Circuits:
IC1: 744C14A
IC2: TA78DS
IC3: 93C56EN
IC4: L2903 *not 12903 from the photos*
IC5: D75108GF(A)
IC6: AN8363UBK
IC7: M6544

Power Transistors:
TR1: D1922 (line 1), E (under last 2)
TR2: D1922 (line 1), E (under last 2)
TR3: G8 (device is very small, next to ZD6)
TR4: B1217
TR5: C458 (line 1), D (line 2), 3D1 (line 3), Google " transistor 2SC458"*
TR6: A143 (line 1), X.SZ (line 2)
TR7: C144 (line 1), ESZ (line 2), Google this P/N NTE123AP*
TR8: C144 (line 1), ESZ (line 2), Google this P/N NTE123AP*
TR9: C1214 (line 1), C (under last 4)

* - Search on Google resulted in transistor for purchase on other sites (not DigiKey or Mouser Electronics).

Diode Arrays:
DA1: P209 (line 1), S. X (line 2)
DA2: DA218

Resistor Arrays:
RA1: *Not Installed*
RA2: E10kΩ39, *Implies 10kΩ resistance)

Crystal:
XTAL: 4190A (line 1), 3N2 (line 2)

Diodes:
D1: *No markings*
D2: *No markings*
D3: *No markings*
D4: *No markings*
D5: *No markings*

Zener Diodes:
ZD1: *Illegible*
ZD2: *Illegible*
ZD3: *Illegible*
ZD4: 1N4742A, DigiKey P/N: 1N4742AFSCT-ND, Radio Shack P/N: 2760563
ZD5: 5 *Partial*
ZD6: PZ627
ZD7: *Illegible*
ZD8: 3 *Partial*
ZD9: 3 *Partial*
ZD10: 30 *Partial*

C15 Decoded - Maybe!
 

I decoded C15 using a capacitor calculator and other Google-fu sources. I am leery about the voltage rating so if anyone replaces this capacitor, try at your own risk then report back to this thread. C15 is stamped "153J50" which breaks down into:
153 - 0.015uF or 15nF
J - 5% (+/-) tollerance
50* - 50V

* - This is an estimate!!! Try at your own risk!!! There are several standards for labeling capacitors!

Cross-referenced to DigiKey and Mouser part numbers would result in this:
0.015uF, 50V, -40 to 85*C (DigiKey) or -55 to 100*C (Mouser), film type capacitor

DigiKey P/N: 493-3457-ND, Manufacturer P/N: QYX1H153JTP
Mouser P/N: 80-MMK5153J50J01TA18, Manufacturer P/N: MMK5153J50J01L16.5TA18

I would suggest trying the Mouser P/N because the "153J50" easily crossed to a P/N, listed the voltage rating at 50V, and it's temperature range falls more in-line with the other caps, typically -40 to 105*C.

Cheers,
George