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Updated FD Speedometer Circuit Board Component List
This update reflects new information on capacitors C9, C15, C16, C17, and all SMD Capacitors. I used a LCR (Inductance-Capacitance-Resistance) Meter to measure these capacitors. A note of "measured xxx on LCR Meter" was used to indicate a measurement with this meter. The most notable changes include a correction to the proper value of C9 and the unit of measure for C16 and C17. Furthermore, C15 reflects a new part number change because the former part did not resemble a ceramic or film type of capacitor.
Note 1: Must use SOT-89 to Through Hole Adapter with SMD type of IC2. DigiKey P/N: 6303CA-ND, Mfr P/N: 6303. Refer to above Post #41 for link to adapter.
Diode Arrays:
DA1: DAP209S (old) or DAP202K, DigiKey P/N: DAP202KT146CT-ND, or DAP202UM, DigiKey P/N: DAP202UMTLCT-ND, Note 2
DA2: DA218 (Original), DA218S (Cross-referenced), May be purchased as New-Old-Stock (NOS) online; ie: UTsource at https://www.utsource.net/itm/p/1482195.html?digipart=1
Note 2: Must use SC-59 to Through hole adapter with SMD type of DA1. Refer to Post #33/Post #41 when using either DAP202K or DAP202UM SMD components as a replacement for DAP209.
Resistor Arrays (Networks): (N/A = Not Used)
RA1: N/A
RA2: E10kΩ391N, Alt Mfr P/N: 4605M-101-103LF, DigiKey P/N: 4605M-101-103LF-ND, or Mfr P/N: CSC05A0110K0GEK, DigiKey P/N: CSC10KC-ND
Power Transistors:
TR1/TR2: 2SD1922, Note 3
TR1/TR2 (Alternate): Mfr P/N: BC33825TA, DigiKey P/N: BC33825TACT-ND
TR3: G8 (next to ZD6), Mfr P/N: FMG8A, FMG8AT148, Mouser P/N: 755-FMG8AT148
TR4: B1217, 2SB1217 (Original), Search ebay or use Alternate P/N: NTE185
TR5: C458 (Original) Cross-referenced to 2SC458, Suggested Alternate – KSC1845, Mfr P/N: KSC1845FTA, Mouser P/N: 512-KSC1845FTA, See Post #45 for more info.
TR6: A143 (Original), Cross-referenced to PDTA143TS, Mfr P/N: PDTA143TS,126, DigiKey P/N: PDTA143TS,126-ND (Obsolete & No Longer Available)
TR6 (Alt01): DTA143, Search ebay for part.
TR6 (Alt02) SMD Replacement: Mfr P/N: PDTA143TU,115, Mouser P/N: 771-PDTA143TU115, Package Type SOT323, Note 4
TR7/TR8: C144 (Original), Cross-referenced to P/N: 2SC144
TR7/TR8 (Alt01): Mfr P/N: 2N2369, 2N2369A, BSX20, Mouser P/N: 610-2N2369A, 610-BSX20, Note 5
TR7/TR8 (Alt02): Mfr P/N: 2N4401, Mouser P/N: 610-2N4401, See Post #41 for more info.
TR7/TR8 (Alt03): Mfr P/N: NTE123AP
TR9: C1214 (Original) Cross-referenced to P/N: 2SC1214. Use Alternates - Mfr P/N: 2N3416, Mouser P/N: 610-2N3416, or Mfr P/N: 2N3417, Mouser P/N: 610-2N3417
Note 3: Order P/N 2SD1922 from La Mesa TV Supply Company. Refer to above Post #41
Note 4: Must use SC-59 to Through hole adapter with SMD type of TR6. Refer to above Post #33/Post #41.
Note 5: Item package is a TO-18 metal can, which is physically different than the original item, C144.
Diodes:
D1: *No markings*, Alternate Mfr P/N: BAW27-TR, DigiKey P/N: BAW27-TRGICT-ND
D2: 4K or K4, Alternate Mfr P/N: MPG06M-E3/53, DigiKey P/N: MPG06M-E3/53GICT-ND
D3: 4K or K4 or 4D or D4, See D2
D4: 4K or K4, See D2
D5: 4K or K4, See D2
Zener Diodes:
ZD1: 30 2
ZD2: 30 2
ZD3: 1 C
ZD4: B4.7, another member successfully used 1N4742A, DigiKey P/N: 1N4742AFSCT-ND, Radio Shack P/N: 2760563
ZD5: .1 (decimal point appears to be in front of the "1"), previous diodes marked as 5 *Partial*, a second diode had "A" and "3" marked on it. It may be "A3" *Partial*?
ZD6: PZ627 preceded by 18A, 17B, 24B (observed from 3 different Speedo boards)
ZD7: 5.A (decimal point appears to be after the "5")
ZD8: A, previous diodes marked as 3 *Partial*, possible match of diode from Post #51.
ZD9: .3 (decimal point marked before the "3"), previous diodes marked 3 *Partial*, a second diode had "A43" marked on it, possible match of diode from Post #51.
ZD10: 30 2, refer to ZD1 and ZD2.
Speedometer Stepper Motor:
M1: S-HR0100, No known replacement.
Surface Mounted Devices (SMDs) on Back Side of Circuit Board:
Note 6: Resistors R14 thru R17 are configured based upon the speed units (MPH vs KPH). Resistors R15 & R17 are configured for Manual Trans cars with MPH faces. Resistors R15 & R16 are configured for Auto Trans cars with MPH faces. Resistors R14 & R17 are configured for Manual Trans cars with KPH faces. I propose the following based upon the logic of the MPH speedometer configuration: Resistors R14 & R16 are configured for Auto Trans cars with KPH faces. I suspect the resistor variation between M/T and A/T comes from the different transmission gear ratios. If there is evidence of this R14 & R16 configuration for an Auto Trans car with a KPH face then that would prove my hypothesis.
I have problem I can't found Zeners P/N for buy new dou have any idea thanks for time
Hello Stamatis,
Thank you for asking about the part numbers for the Zener diodes. Another forum member had success with replacing ZD4 with one from Radioshack. They are out of business but it does cross-reference to a Zener diode that is available at DigiKey (www . DigiKey . com). No part numbers are available for the other Zener diodes. Please see the list of part number from Post #76.
If you have a problem with your speedometer board then you could read/follow/post at my associated thread here: Troubleshooting the FD Speedometer. If you post photos of your circuit board then I could offer some advice. These boards suffer the most from old and leaking capacitors. When the acid from a capacitor is left on the board for a long time then it will cause damage to other components.
I wish I had better news to tell. Does that answer your question?
Thanks for asking. The LCD is a robust component on the speedometer board. Its failure is far less than other components. I do not have a part number for it. Why do you suspect the LCD is bad on your board? If your odometer disappeared then I highly encourage you to read through the link posted in Post #78, above. The most common failure on these aging circuit boards are leaking capacitors. Moreover, leaked capacitors can cause surrounding components to fail.
Hey, thanks for hte reply. I've got a speedo here and the LCD itself just generally looks a bit funky (maybe water damage or its been physically damaged) so was hoping to replace the whole LCD it to freshen it up
The LCD is a specialized component that does not have any part numbers. You could source a failed speedo in the classifieds to cannibalize the LCD. One word of caution about LCD replacement: the legs to the LCD are very long for solid state components. It is VERY easy to bend them during removal. They could be reshaped using a very small pair of needle nose pliers or jeweler's pliers (ones without serrated jaws).
Please share a photo of your LCD here: Troubleshooting the FD Speedometer thread. Sometimes, the polarized filter on the LCD becomes crazed.
Last edited by Gen2n3; 04-12-20 at 06:47 PM.
Reason: Updated the proper pliers.
Thanks to George (Gen2n3) advice I fixed also my speedometer.
If You like me removed the needle of Your speedometer and then You lost the correct position I found that with 280 km/h speedometer the end of the scale should be pointed with the back of the needle pointing 105 km/h
note: You don't need to remove the needle to fix the speedometer, was my mistake.
Zener Diodes: ZD1: 30 2
ZD2: 30 2 ZD3: 1 C ZD4: B4.7, another member successfully used 1N4742A, DigiKey P/N: 1N4742AFSCT-ND, Radio Shack P/N: 2760563 ZD5: .1 (decimal point appears to be in front of the "1"), previous diodes marked as 5 *Partial*, a second diode had "A" and "3" marked on it. It may be "A3" *Partial*? ZD6: PZ627 preceded by 18A, 17B, 24B (observed from 3 different Speedo boards) ZD7: 5.A (decimal point appears to be after the "5") ZD8: A, previous diodes marked as 3 *Partial*, possible match of diode from Post #51. ZD9: .3 (decimal point marked before the "3"), previous diodes marked 3 *Partial*, a second diode had "A43" marked on it, possible match of diode from Post #51. ZD10: 30 2, refer to ZD1 and ZD2.
I believe the partial markings on ZD1, ZD2, and ZD10 represent the voltage and voltage tolerance (30v, +-2% tolerance)
Digikey has these - Zener Diode 30v, 2% tolerance which makes sense with the markings
Mouser Electronics also has them, same voltage and tolerance specs, but different manufacturer (Taiwan Semiconductor Corporation).
Don't have a link to the Mouser Electronics page since their site is down but the images look exactly like the zener diodes on the speedometer board.
I am not 100% certain but this makes the most sense given the markings. Gonna order this off digiket as well as some other capacitors and try to convert my JDM cluster to miles.
Zener Diodes: ZD1: 30 2
ZD2: 30 2 ZD3: 1 C ZD4: B4.7, another member successfully used 1N4742A, DigiKey P/N: 1N4742AFSCT-ND, Radio Shack P/N: 2760563 ZD5: .1 (decimal point appears to be in front of the "1"), previous diodes marked as 5 *Partial*, a second diode had "A" and "3" marked on it. It may be "A3" *Partial*? ZD6: PZ627 preceded by 18A, 17B, 24B (observed from 3 different Speedo boards) ZD7: 5.A (decimal point appears to be after the "5") ZD8: A, previous diodes marked as 3 *Partial*, possible match of diode from Post #51. ZD9: .3 (decimal point marked before the "3"), previous diodes marked 3 *Partial*, a second diode had "A43" marked on it, possible match of diode from Post #51. ZD10: 30 2, refer to ZD1 and ZD2.
I believe the partial markings on ZD1, ZD2, and ZD10 represent the voltage and voltage tolerance (30v, +-2% tolerance)
Digikey has these - Zener Diode 30v, 2% tolerance which makes sense with the markings
Mouser Electronics also has them, same voltage and tolerance specs, but different manufacturer (Taiwan Semiconductor Corporation).
Don't have a link to the Mouser Electronics page since their site is down but the images look exactly like the zener diodes on the speedometer board.
I am not 100% certain but this makes the most sense given the markings. Gonna order this off digiket as well as some other capacitors and try to convert my JDM cluster to miles.
The diodes mentioned above will work but may prematurely damage TR3 from too much input amperage.
Cathodes of ZD1 and ZD2 trace to the Collector pins on TR3 which have a max input voltage of 30V @ 10.6mA (if I'm reading the spec sheet and calculating right)
So in theory you should be able to use any Zener diode up to 30V as long as the amperage is 10.6mA or less.
If anyone else wants to chime in it would be appreciated.
I'm basically looking at what the zener diode supplies and working backwards to figure out correct voltage and power rating.
For the Zener Diodes, does any one have them available and out of the cluster?
Mine appear to be pretty burnt out with black marks at the anode side.
Perhaps they could do a quick test, such as the video below to identify the breakdown voltage of the diode? That's the only statistic we will really need to source replacement parts I think???
@rotard7 I'm not sure the markings would correctly indicate the zener voltage of the diodes. The one part # we have available, 1N4742AFSCT-ND, has a zener voltage of 12V which makes sense as a voltage regulator. Would there be any reason for the zener voltage to be greater than 12V?
For the Zener Diodes, does any one have them available and out of the cluster?
Mine appear to be pretty burnt out with black marks at the anode side.
Perhaps they could do a quick test, such as the video below to identify the breakdown voltage of the diode? That's the only statistic we will really need to source replacement parts I think???
@rotard7 I'm not sure the markings would correctly indicate the zener voltage of the diodes. The one part # we have available, 1N4742AFSCT-ND, has a zener voltage of 12V which makes sense as a voltage regulator. Would there be any reason for the zener voltage to be greater than 12V?
This is some what going to be lengthy so I apologize in advance.
The Zener voltage IS the breakdown voltage when referring to Zener diodes. (https://www.digikey.com/en/maker/blo...d-applications)
It would make sense for them to be rated as high as 30v seeing as how there are multiple capacitors rated at 50v on the Speedo board and that voltage regulation would need to be regulated to prevent damage to lower rated voltage components. If you end up using a 12v zener diode in place of a 30v zener diode you will most likely fry it given time.
Also mentioned in my second post is that the Cathodes on ZD1 and ZD2 are connected to the collector pins on TR3 (which is a Dual NPN Transistor with a single emitter) and has an ABOSULTE MAX of 30V input on those pins which is why the Zener diodes would be rated at 30V. (data sheet - TR3 - FMG8A Datasheet)
I've already removed and replaced ZD1 with Digikey 1727-4734-1-ND and haven't had an issue. This is a 2% tolerance diode, but if you were to use a 5% tolerance diode I would suggest going down in Zener Voltage to 28v
Using the test posted in the link above I can confirm that my original ZD1 has a Zener voltage / breakdown voltage of 29.3v, confirming it has a zener voltage of 30v.
With this info I think it's safe to say that ZD1, ZD2, and ZD10 are all 30v zener diodes.
Based on reading different data sheets from different manufactures its a literal Cluster F*%k trying to decode these diodes. Some manufactures are using letter designations to differentiate from tolerances while others are using them to differentiate between different series of diodes in their product lines.
Last edited by rotard7; 11-20-20 at 11:18 AM.
Reason: grammatical spelling nazi
Your diodes that look burnt is the result of leaked electrolyte that crusted over from C3 (referencing your post in the just got done figuring out how to fix an FD odometer thread). They will clean up very nicely with isopropyl alcohol and toothbrush/cotton swab. They will most likely be fine.
It is important to remember that testing a Zener diode must be done out of circuit, as demonstrated in the video link you provided and also from rotard7's post above. If you want to test the Zeners on your board then each one would be desoldered then tested in a similar fashion from the video. If you are going to go through the trouble to remove them from the circuit then it makes better sense to replace them. Discrete components like diodes, resistors, capacitors, etc are consumable items - once removed from a circuit they are replaced with a new unit. The reason for this approach is from a reliability stand point. Can it be re-used - yes but the likelihood of failure could increase when compared to a new component. My recommendation would be to leave the diodes in the system until failure or all other avenues have been exhausted.
Again, as rotard7 posted, his research and results offer a solution with some trade-offs, such as damage to TR3.
rotard7,
I would like to read more about your research so we can identify some options for Zener diode replacements. I'll dive more into your work over the weekend. Thank you for the hard work in research!
Thank you for the explanation, appreciate the education.
As George pointed out, I'll leave the diodes on the board to prevent further damage to components so cannot test zener voltages but hopefully somebody with a sacrificial cluster can give it a go.
I'll replace the caps as suggested and go from there to further troubleshoot.
I would suggest replacing all electrolytic capacitors. C15 is the only capacitor that shouldn't need replacement because it is not an electrolytic capacitor and is far less likely to fail.
This doesn't pertain to the speedo board but I do want to mention it. It seems like the 99+ tach's are missing a zener diode on the stepper motor board.
I don't have a pic of my 99+ tach board since its been reinstalled into my car but I noticed this when I disassembled it and compared it to my USDM tach board.
Pic below shows my USDM Tach board - circled in read is the zener diode that is missing from my JDM (6 'o clock) cluster tach.
I put my jeweler's loupe on that Zener diode. The body read "1AZ2.0". Will need to research that further. Thank you for pointing out that difference! The samples that I studied must have been JDM tachs because they did not have that Zener diode!
Maybe someone can help me with this sort of on topic question. My stock cluster with non functioning odometer was destroyed by UPS when I was sending it to Zepco for repair. I found a replacement cluster that functions perfectly but the mileage is about double the true mileage on my car. Do I have any options to get this reprogrammed so that the information is accurate?
You can move the odometer chip from one to the other.
Michael Gagne in Canada does amazing work fixing clusters, he can totally help you with this. He's active on the RX-7 FB group and he's on here as Str3atWarrior.
He has an RX-7 and a full test setup to test and calibrate clusters.
Unfortunately UPS wouldn't return my package. The semi that had my package was involved in a rollover accident. Even after pleading and begging UPS to send me the crushed box, they said that they couldn't do it. I'll message Michael and see if he can do anything. I'll tell you, this makes me just sick to my stomach!
Thanks for the quick reply Dale.
I guess we're brothers in a sort of a way. I've got a 94 FD R2 in Brilliant Black as well! Can I see some pics of yours?
09-23-19, 11:33 PM
Updated FD Speedometer Circuit Board Component List
