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Digiplex on my Paso 906 did not work correctly cause to intermittent problem on vertical cylinder ignition.
Therefore, I have opened the box and I have detached all connections from circuit to the framebox.
Inside it I found the circuit completely covered with a protective rubber plus 2 big transistors. I suppose the problem was one of final power transistors. I frozen over/around it with electronic circuit refrigerant gas and immediately the vertical cyl begin to run.
Quickly, I run to buy two new transistors (BU931ZP – price € 4.50), replaced it but, with great disappointment, the vertical cyl did not work fine.
Therefore, without fear, I began to remove delicately, with a toothpick, the rubber from the circuit.
I found few electronics components under the rubber and many great lines from the transistors to external pin 10 11 12 (pin towards the coils).
When I freeze one of this lines, vertical cyl begin to run.
Sure and happy to have solved the problem, I have solder bridge from transistors (which one link to pin 11 - vertical cyl) to external pin and all it has worked.
I Am much happy, Ciao a tutti

P.S. in the afternoon I post same photos

Well done, thx f sharing!
Looking forward to pics.

Tamburinifan wrote:Well done, thx f sharing!
Looking forward to pics.

Some pic of Digiplex inside,

circuit without rubber


bridge to solve problem on my digiplex

This shows the lenghts folks will go to keep their Pasos running.

Help and electrical fool understand something. Why does freezing the circuit make it work??

jcslocum wrote: ... Why does freezing the circuit make it work??

Often, when defective semiconductors are warm do not work,
also warm defective circuit line (for thermal expansion) are interrupted,
freezing them could momentarily work.
This technique is normally used to find broken off component on electronic circuits.

, FAQ material!
Do you have a wiring schematics of the Digiplex as well?

Tamburinifan wrote: , FAQ material!
Do you have a wiring schematics of the Digiplex as well?

unfortunately not. I have asked to Magneti Marelli but nobody has answered.

So how did you know to make additional wire in pic 2?

Tamburinifan wrote:So how did you know to make additional wire in pic 2?

In italy it is said “FATTORE C” (traslate => “B FACTOR” B=BUM/BUNS/BATTOM), a stroke ok lucky.

Cause intermittent fault, I have tried with same bridge (additional wire) to reinforce
the circuit line toward vertical cylinder transistor and toward external pin 11 (vertical cylinder coil).
In the beginning I suppose the problem was on big line, but little line was broken off, this line carry
signal to base of power transistor
(http://www.datasheetarchive.com/pdf-dat ... 152462.pdf).

Sorry, this is a complete Digiplex pic (by internet)
Transistor are under vacuum device.


transistor location, green line are the original bridge to carry hi current


original bridge

Thx again!
We can probably run our Paso`s forever when guys like you chime in...

Do you work w electronics f a living?

So, if it only was a circuit fault, it could be quite easily redone for a perfect recover...
Great job!
Ciao