Motorcycle digital speedometer repair

Discussion in 'The Projects Forum' started by ChillFancy, Jul 6, 2014.

  1. ChillFancy

    Thread Starter New Member

    Jul 6, 2014
    1
    0
    Hi all,
    I diagnosed my Suzuki GSX-R 750's lack of MPH indicator and found a burnt component on the speedometer. I'm looking for some help identifying the part so that I can make the repairs to the board. This is damage to the Black/Red wire circuit that outputs voltage from the speed sensor. My bike ran in overvoltage condition which burnt the speed sensor AND sent overvoltage power direct to the speedo.
    What is ZD70? I assume it is a Zener Diode but the 22 amp 60 designation doesn't make sense, since they are labeled by nominal voltage and wattage usually. Its hard to see but the component hits the circuit once next to the "C" of CL70, then the component connects again near the "A" near ZD70.
    [​IMG]
    [​IMG]
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,226
    Sorry, vehicle mod discussions are verboten on this website. You might try this.
     
  3. john_doe01

    New Member

    Nov 27, 2011
    24
    0
    had a quick look for the part number with no luck. from past experience id say 60 is the date code of the part, so id stick a 22V zener in and hope for the best...
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,421
    3,357
    It is possibly a 1N5922A 7.5V 3W zener.
    Obviously high current flowed through and over heated the PCB trace. The bad zener itself might be the consequence of the fault. The fault could still be lurking around someplace else.
     
  5. absf

    Senior Member

    Dec 29, 2010
    1,492
    371
    If you measure the B/R point with an analog ohm-meter, what is the resistance there to 0V reference point? Was it shorted to Ground?

    If the current flows from right to left then something connected there must have been shorted.

    Allen
     
  6. bwilliams60

    Active Member

    Nov 18, 2012
    722
    88
    I just wanted to get some clarification on this for future reference. The word mod is used here as in modification and yet he has not asked a question in regards to modding this board. I see an electronic problem, he sounds fairly knowledgeable with what he is doing, and is asking for help to fix an electronic problem. Am I to understand that as long as the word bike or car is used, we cannot help him? If we take the bike or car out of the equation, can we help him?
    Please understand, I am not trying to be smart, just want to be politically correct on the forum.
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    I'm not a moderator, but I think the reason for stopping auto mods discussion that has always been placed foremost was safety.

    If someone modifies a critical component on a vehicle and causes injury or liability etc, it's bad for the forum and its contributors.

    Likewise if someone tries to repair a critical component and then use the vehicle we have to ask; does that also carry the same safety issue?

    Personally I think it does, but like I said I'm not a moderator so it's going to be their opinion that counts here.
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,421
    3,357
    Just because there is a reference to car, bike, automotive, etc. does not automatically mean that the post will be banned.

    A post that tries to circumvent the rules by removing references to car, bike, automotive, etc. will still be banned if there is a safety violation.
     
    absf likes this.
  9. Experimentonomen

    Member

    Feb 16, 2011
    331
    46
    I dont think a repair is viable here, the death of the zener and the frying of the trace could well mean the ICs are dead too.

    And im not sure if replacing a intrument cluster is even legal as that would change the odometer for total miles driven.

    In fact i think that when the electronics fails enough that the odometer is erased and the cluster has to be replaced, the vehicle is no longer roadworthy as future owners and inspectors cannot know the vehicles actual mileage, and thus has to be scrapped.

    So i think this thread should be closed.
     
  10. bwilliams60

    Active Member

    Nov 18, 2012
    722
    88
    I think in the right hands, a repair is always possible with instrument clusters but cost will come into play. Most instrument clusters, depending on the extent of damage will retain odometer readings in EEPROM and in the event that the odometer reading is lost, the odometer can be replaced with a new one and programmed to the last known mileage or recorded mileage. In Canada, we are required to record our mileage when we get our license renewed. We do not scrap vehicles because the odometer reading is out. That would be very expensive.
    To the moderators and RB, I thank you for clarification on your rule, I respect it and will abide by it. I have a hard time watching some of these go by because I have seen and done the repairs for many of them and I want to reach out and help, but not at the cost of a liability suit.
     
  11. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,675
    899
    Well, we don't know from what country some of these replies originate. In the US, it is perfectly legal to replace an instrument cluster. One has two options, speaking from my experience many years ago. You can get the old and new (usually 0) mileages certified, or you can claim that the mileage is unknown. I did the former as the vehicle had only 49,000 miles on it. Today, there may be other options.

    As to the OP's question, I am a bit concerned the identification of the circled item has not been challenged. It looks like a 0.22 uF, low-voltage (e.g., 6V, possibly tantalum) capacitor. That is, what was read as "22A" is almost certainly "224", which means 22X10E4 uF.

    As for curing the problem by replacing the damaged components, one can never say "no chance," but I agree with those who express doubt about success.

    John
     
  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    No it's part number marked on the PCB "ZD70" so is unlikely to be a cap, and also both ends are marked "K" and "A" which matches other diodes on the PCB.

    The Suzuki instrument clusters send power out to the speed sensor, this is probably that line. It is generally less than 12v, (maybe 9v?) as it is a crudely regulated rail.

    Connecting battery 12v to that rail would cook the zener really bad, depending how it was fused.

    The speed sensors are not that critical for voltage, something like a 10v or 9v zener should be ok. It looks to be supplied on the PCB via R70 and/or R71 (100 ohms) which is typical for a crudely regulated rail.

    It's unlikely to have damaged anything else in the cluster as the other side of those resistors is IGN +12v, so the only things likely to be destroyed are the zener and the track.

    (It's cool to be able to do auto electronics here! Doesn't happen that often). ;)
     
  13. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,675
    899
    For reference, this is the "circled item" to which I referred. I can't see the end makings and the PCB label "ZD70" you describe on the original image. Could you highlight them?

    Capture2.png

    John
     
  14. Experimentonomen

    Member

    Feb 16, 2011
    331
    46
    He means the charred rectangle to the right above the circled part. The charred rectangle suggests said zener diode has completely vaporized, taking both its solder pads and part of the traces with it.
     
  15. MrChips

    Moderator

    Oct 2, 2009
    12,421
    3,357
    The image is large, 2248 x 2589 pixels. Scroll to the right to see the charred PCB.
     
  16. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,675
    899
    @Mr. Chips, Please re-read my post #11. I know which item has been identified as the zener. That was not what I was talking about; apparently, Mr RB thought it was.

    The capacitor's relevance to the zener may be its voltage rating, which if circuit traced may give a clue to the zener's voltage.

    John
     
  17. MrChips

    Moderator

    Oct 2, 2009
    12,421
    3,357
    So your question is, "Is this component a capacitor or zener diode?"

    "Is the marking 224 or 22A?"

    We have to wait for the OP to give us a clearer picture.

    I appears that he is gone forever, in which case we might as well close this thread.
     
  18. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,675
    899
    I did not ask a question. I made an observation. Mr RB concluded that component was clearly marked as a zener. That is not the case.

    I believe it is clearly a capacitor, as stated in my post. If you think it is a zener marked "224", what is your evidence for that?

    John
     
  19. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Sorry Jpanhalt I should have been more clear. :)

    I made a direct assumption that the rectangular part was indeed the only part missing from the PCB and used to live above what is now the only charred rectangular empty space.

    So the PCB markings ZD70 and K and A are very relevant.

    If you disagree with that assumption, please show where the "cap" went on the PCB photo?

    It's not a cap, it's a diode. That is a perfectly normal size, appearance and markings for a SMD diode.

    I believe the marking is "224" not "22A" from looking at it.

    It's probably a 1W zener size, so a 10v 1W zener should be fine.

    It's Anode is clearly connected to a large heatsink plane, connected to the ground plane. Typical for a power zener in an instrument gauge. Its Kathode is supplied via one or both of the 100 ohm resistors from the +12v rail. Exactly as would be expected for a crude regulator, and also fully explains the failure mode where the OP has connected battery 12v to its cathode causing zener fusing and track melting.

    I know the Suzuki speedo systems operation quite well, and developed a commercial product to connect to them.

    The crudely regulated rail comes out of the cluster gauge and powers the 3 wire hall effect speed sensor down near the gearbox, the voltage is 9v or 10v going from memory but it is not critical. It only needs to supply current of about 20-25mA to the speed sensor.
     
    Last edited: Jul 9, 2014
    bwilliams60 likes this.
Loading...