When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 94 5 speed FD with a dead speedometer. I've done some work on the speedo board to replace capacitors with parts that I had on hand. The repair work so far has resurrected the odometer LCD panel but the needle on the speedo still isn't moving -- except for a brief ~1 second rise to 20mph and then back to zero shortly after reinstalling the cluster after capacitor replacement. The odometer LCD displays accurate mileage but no longer increments. The tachometer works and I've verified that the VSS is sending voltage by measuring varying voltage with the rear wheels turning between pins 3A and 3B on the instrument cluster connector for the speedometer.
Initially C3 was leaking and ran down the entire length of the board and across the solder points for the LED panel. This is what prompted replacing most of the capacitors
The only capacitors I haven't yet replaced are C15, C16, C17 and the small surface mount capacitor on the back side of the board. Is it best practice to replace these as well?
I'd love some ideas on what else I can do short of a completely rebuilding the board to try to troubleshoot the issue. Any ideas / guidance is genuinely appreciated.
I had an issue with speedo when it would move to 20mph even if car was not moving (i was replacing the caps for the display issue and probably messed something else). Turned out speedo IC was shot. Eventually I sent my board (along with another used speedo) to Michael Gagne so he could properly swap the IC etc..
Mine also reads 20mph upon ignition power, I ended up setting up a bench testing to verify the speed sensor which produced the same results. I also checked using the factory service manual test procedure. I guess Ill be sending mine off too.
Quick question for any circuit board pros still monitoring the forum. It looks like IC4 is pretty heavily corroded. The circuit diagram in this amazing thread seems to indicate that IC4 is an LM2903. LM2903DT is available as tape and reel from DigiKey but there is a minimum quantity of 2,500. Obviously that's a few more than I need. Mouser, which sells the tape and reel in individual quantities, has two parts listed for LM2903DT. Is one preferred over the other? I assume the ROHM chip would suffice?
I had an issue with speedo when it would move to 20mph even if car was not moving (i was replacing the caps for the display issue and probably messed something else). Turned out speedo IC was shot. Eventually I sent my board (along with another used speedo) to Michael Gagne so he could properly swap the IC etc..
Do you have any information on which IC he replaced on your board? I can likely do the repair on mine with the soldering experience I have. If you have any contact information on Michael that would be great, maybe I can reach out to him about mine. Thanks
Do you have any information on which IC he replaced on your board? I can likely do the repair on mine with the soldering experience I have. If you have any contact information on Michael that would be great, maybe I can reach out to him about mine. Thanks
I tried linking Michael's facebook profile but it keeps getting blocked. Message Michael Gagne' on Facebook Messenger.
08-19-24, 12:41 PM
