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Forum Tatra 603 Ignition

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2016-08-21 08:08:49

Hi everybody,

i have a problem with my tatra 603 right now. The car doesn't start anymore due to no ignition. The car has the thyristor system. I checked everything. The distributor send a 0,5V signal to the electronic ignition controler. The ignition has a constant 340V output wenn the engine is not running. Wenn trying to start, the voltage lowers to 240V to the ignition coil. I changed and tried different ignition coils but I still do not get the spark plugs to lighten. I tried to find documents to see wich part is defect but I got nothing at the time. Does anbody has an idea what is going on and which part I would need to change. Thanks for your help.

2016-08-21 22:03:22

jrouso: I don't know about the original Tatra system but my engine has programmable MSD 6AL2 controller, MSD blaster 2 coil & a Mallory Unilite distributor. You need different spark plug wires for the MSD ignition. That will start it.

2016-08-31 12:32:09

I use a MSD 6a with Tatra original electronic distributor with a Beru coil for electronic ignition and MSD spark plug wires.

It had worked fine for me the last 7-8 years.

2016-08-31 13:22:09


the output voltage seems ok; check the schematic - after impulse from magnetic sensor, thyristor Ty is conducting, and energy from capacitor C5 is discharged to ignition coil ZC. You have to be carefull, the ignition coil is not 12V, but 6V to work. You can order it from here:

When you don´t have incorrect ignition coil, maybe C5 lost his capacitance, but it is quite rare failure (the original Tatra parts were designed with high quality).

Let us know, if this helped...

2016-08-31 15:01:17


Great thanks you for the help. In the mean time I orderered new parts. Indeed I had a 12V coil which may have damaged the electronic. I will send the electronic controler to a specialist to check it thanks to the shematic.

I will keep you informed


2016-08-31 16:55:05

You're welcome.

Inside older T603 were also used 12V ignition coils, but this was used together with mechanic contact breaker. This can be little confusing...

I don't think, that the electronic switch is damaged, but you (or technician) can check it. I think because of more turns on ,,primary" side of ignition coil, the voltage on secondary side was only lower value, and no sparks was visible.

Check the diodes to be sure (but when voltage was above 300V they will be fine), and the capacitors near the thyristor. But unboxing of the electronic switch can be little tricky - better do not unscrew the input/output terminals, because it will twist the wires, but only take some pictures first and then desolder them.

Be careful not to injury because of higher voltage; after turning switch on, It will produce hearable sound tone, but I'm sure you are familiar with this.

Good luck :)