1 minute ago, Captain Obvious said:

Well this may all be for naught... I got a head start based on the pics from that Dime Quarterly thread I started looking for info on the IC chip - AN603.

Based on the logo, it looks like a Matsushita (now part of Panasonic) part, but I couldn't dig up any info about it at all. So if I can't find anything about what's going on inside that chip, I might not be able to do much with it. I mean, I can certainly do a macro level reverse engineering and infer what's going on inside that chip, but that may be about it.

And if it looks like there's something wrong inside the chip, I certainly won't be able to get a replacement except from another old donor part.

I wonder if they used that same chip in the current sense Z tachs... Those are at least easier to find at this point.

Anyway, regardless, I'll do what I can.

Apparently DQ also has an article on grafting in the tach from an S110 200SX. There are several NOS tachs on ebay now. It's not cheap, but it would probably be a fix Cody could enjoy for a long time.

9 minutes ago, Captain Obvious said:

Well this may all be for naught... I got a head start based on the pics from that Dime Quarterly thread I started looking for info on the IC chip - AN603.

Based on the logo, it looks like a Matsushita (now part of Panasonic) part, but I couldn't dig up any info about it at all. So if I can't find anything about what's going on inside that chip, I might not be able to do much with it. I mean, I can certainly do a macro level reverse engineering and infer what's going on inside that chip, but that may be about it.

And if it looks like there's something wrong inside the chip, I certainly won't be able to get a replacement except from another old donor part.

I wonder if they used that same chip in the current sense Z tachs... Those are at least easier to find at this point.

Anyway, regardless, I'll do what I can.

This AN603, @Captain Obvious? https://shop.ectransistors.com/PANASONI-AN603-CDIP-14-.html

3 minutes ago, SteveJ said:

This AN603, https://shop.ectransistors.com/PANASONI-AN603-CDIP-14-.html

Who knows... Maybe? Those sites always seem to have stock of any IC you are ever looking for. But do they really? I don't think I'd ever trust them enough to even try

11 minutes ago, SteveJ said:

Apparently DQ also has an article on grafting in the tach from an S110 200SX.

Yeah, that's the article in which I found the pics I was talking about. This is a 200SX on the left and 510 on the right.

Oh, and youtube says the current sensing Z tachs don't have any IC's at all. Nothing integrated. Just discrete transistors.

So I assume YouTube is incorrect?

22 minutes ago, Captain Obvious said:

Who knows... Maybe? Those sites always seem to have stock of any IC you are ever looking for. But do they really? I don't think I'd ever trust them enough to even try

After a little research, I would concur with your assessment. 

We've been working on the tachometer for the 510. They are pretty rare. The one I bought didn't operate and the good Captain helped me with that, but I didn't get the bezel that the tachs had and they are pretty much unobtanium,

So we decided to cannibalize the old dummy light panel to make a bezel.

I made some more progress today. I will try to make the finished pictures tomorrow

I also plastic welded and stapled the torsion bar cover for the hatch springs. This is also a difficult panel to source and is pretty thin. Lime maybe 2mm. Hard to repair

We will try to add some texture and paint it black

Blacked out some of the lens

Shroud installed

lens

Cluster

Edited December 22, 2025Dec 22 by Patcon

Cody's tach is installed but not functioning. It will need some more diagnosing when he's back in town

55 minutes ago, Patcon said:

Cody's tach is installed but not functioning. It will need some more diagnosing when he's back in town

If you disconnect the tach, does the car still run?

So the tach loop is junctioned near the fuse box. Routed through the tach and rejunctioned near the fuse box.

So you would like me to break that loop and see if it runs?

If you disconnect the tach, and the car runs, it would mean that the tach isn't in the ignition circuit. The other things to check are the power and ground to the tach in the dashboard.