Zeeltronic PDCI-24V and tacho problems

[torp68]

Hi

More questions regarding implementation of the Zeeltronic PDCI-24V. All put together, and everything apparently works fine. The only thing is the tacho..... I see a lot of tacho-problems described on this forum, but I cannot find my exact problem described. It is constantly "underreading" the actual rpm. Seems to be indicating in the region of 3/4´ish of the actual rpm (double-checked with handheld Zeel controller). I have emailed Borut, described the problem and got this answer:

Hi,
Are you able to get Zener Diode BZX85C62?
Connecting Zener Diode in serie should help.
Buy 2 Zener Diodes, just in case you will have to use both.
https://no.farnell.com/vishay/bzx85c62- ... y%2Fsearch

Regards,
Borut

I doubt there's any problem with the harness, as everything else works fine. Tacho worked fine before. Battery is new. I have changed the coils and took Rick Lance´s advice from this link to get the ones with the right primary resistance. http://www.rzrd500.com/500phpBB3/viewto ... =5&t=14706 leading me to buy these https://www.ebay.com/itm/V-Twin-32-9342 ... xQ&vxp=mtr
I'm using the tacho-output (Y/G) on the PDCI-24V. (not the output for non-original rev counter G/B).

Anybody used these zener-diodes in this setting before?
Any other thoughts/comments?

Regards
Oyvind

[pstamper]

I could not get tach and kept trying g different connections till it worked. Think it was an orange to a coil.

[torp68]

I've seen that method mentioned on here a couple of times. If that's a safe way to do it (for the tacho), then maybe I´ll have to give that a go also.....

[MK]

The stock RD tach works on HT primary signal (= orange cable at the coil).

My guess would be an insufficient 12V supply (faulty reg/rec and or battery). This often makes tachs reading random stuff.
And tachs also can have errors. Has it worked before or did you hook up another tach showing the same symptoms?

[torp68]

The battery is new and charging is good. Relatively new reg/rec. No other tach available to swap, but it worked before the Zeel/Coil modification. The recommendation for the new coils came from from Rick Lance, so I trust those are good. Oh well.....

[torp68]

Seems my tacho is dead, more or less...... It´s doing its own thing constantly now. No change when taking the signal directly off the orange wire to the coil. Reg/rec and battery is ok.
I see from other posts that the FZ750 is (sizewise) a direct fit. Redlined at 11000 rpm, but I can live with that. I also understand from previous posts that the combination of the original CDI, 0.5 ohm coils and the FZ750 tach is not the best combo.
However; Since I have the Zeel PDCI-24V installed, I was wondering if I could use the Zeels output for "Non-original rev counter (G/B)" with a FZ750 tacho (or any other Yamaha 4 stroke tacho from same era)...? Anybody got any experience (or thoughts) on this?

Regards
Oyvind