How would I go about wiring this one up? RadioShack doesn't have a 1M-Ohm trimmer, any way to make a substitute or are there any exact values out there for what to use when converting a 4 cylinder tach to a V6 tach?
I mapped out the modded board that is shown in other threads and followed relating the pins and labels on this board. The gauge cluster for the Sunbird was remade so no aux wire is needed for the boost gauge on the tach board. The wire on the other boards modded is labeled BS(BooSt). That extra screw terminal is labeled BS and moved above the tach stepper terminals. It has some slight differences obviously, but operates the same with the same hardware. All the studs are the same length.
Others technical info and input would be great for this. For 'Just to know' reasons.
The IC for the boost portion of the board is labeled 9907A CS8851J. I am having no luck finding any info on this chip... maybe someone else can locate info for this chip?
[This message has been edited by XgovernmentAgent (edited 02-25-2013).]
Like I said earlier, one of the examples in that datasheet is the exact circuit GM uses for the gauges. Trace the boost gauge circuit out, you'll see it.
I don't have my Fiero stuff handy, else I'd go into a little more detail.
OK, so I got the new tach. I modded the housing so it will fit. I put the 1Meg ohm trimmer pot in place of R14 and cut the foil run. This tach is the less desirable one because of the face so its not covered as far as I can find. The PC board is different than most covered MODs.
This is mine and how I did it.
I used Torque to calibrate the tach. I haven't wired in the boost gauge yet.
[This message has been edited by hercimer01 (edited 01-22-2014).]
Looks good ! My 85 has the non-backlit instrument panel , but I am getting the urge to change that after seeing your work here. Backlit guages look so much better (you can actually read them at night!)
Looks good ! My 85 has the non-backlit instrument panel , but I am getting the urge to change that after seeing your work here. Backlit guages look so much better (you can actually read them at night!)
These aren't finished yet. I tried them in the car with the lights on, and they need some more work. The Red back-lit overlay needs to have each light transfer segment enlarged for better light transfer through to the front layer. Also i'm not sure how these will come out printed onto the final medium. I plan to use clear plastic for the red back-lit layer and sticky white paper for the top finish layer.
Also the boost segments dont make sense. They need to be divided up into 5 PSI segments.
[This message has been edited by hercimer01 (edited 01-25-2014).]