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**A basic TCI repair**

If your “black box ” / “CDI unit” Correctly called the TCI unit goes bad it is probably one of the 2 fast switching transistors inside of it which are responsable for the timing on each coils. (ringed in Red and Blue in the picture )

One transistor will send a signal to the coil on the left. The other one will send a signal to the coil on the right.

Now the coil on the left provides sparks for pistons 1 and 4.

The coil on the right provides sparks for pistons 2 and 3.

If one of the transistors inside the TCI is burned or not working at it's optimum specs the sparks on the pistons that it is in charge of, are going to be missing or are going to be too weak to set the fuel mixture off.

If that is what is happening with your TCI unit. It's a cheap and easy fix if it's done by someoane qualified.

A picture of the “works” of a FZR TCI unit with the TCI unit. The replacement transistor is a Bosch BIP373 IGBTs (about 8USD from autozone )

the one surrounded with red was the BAD transistor. It was responsable for the sparks from pistons 2 and 3. Got it replaced. Make sure to tell the electronics guy to put some cooling paste between the transistor and it's heat sink& be sure that no transistor leg touches the heat sink !

Best of Luck TrifGeorge

Some new information:-

From this picture :- Top to bottom:

  • resistor Br B R Gd = 1k, 5%
  • Zener, unknown,

band left in the pic. “A2” marking on the side; no idea what the rating is. Logic suggests it's either 5v or 12v; try 5v first so you don't burn anything that doesn't like 12v!

  • resistor Bl R Br Gd = 620, 5%
  • resistor R R R Gd = 2.2k, 5%
  • resistor Bl R Br Gd = 620, 5%

The tach signal is tied into the 2-3 spark signal. The earlier model tachs simply picked up the fly-back pulse from the coil, while the newer tachs want a 12v or 5v signal from the TCI (not sure which voltage; this will very likely be tied into the Zener diode rating).

The tach may come back to life once you replace the TO-220 ignition transistor.

Info supplied by DONTZ125, Picture by AndersJ

Editted extras by Y-G & supplied by ReelRazor

tci-repair.txt · Last modified: 2020/10/19 11:50 by