Speedo problem

["Norberto Altalef" <nalt@domain.elided>]

My speedo has problems again.

A year ago, a faulty transistor burn a resistor.

I received a couple of mails from the group and I change the transistor and
put a resistor with a high disispation value. Also mount the transistor out
of the speedo case (behind the instruments).
I use a TIP32 transistor and 4.7 OHM resistor.

Well, OK for a year.

Now, the speedo electric motor becomes blocked and the resistor and
transistor heats a lot.
The resistor burns a capacitor near it and there was a lot of heat behind
the dashboard and some smoke too.

With a lot of patience I disassembly the speedo mechanism and finally clean
an lubricate all and reasembly all.

I change the resistor and transistor for one of the same type that before.
I change the capacitor too. I'm not totalley sure about the value, because
the case was partially burned.

But this time, I'm not so lucky.

First. With the engine on, but with no moving the speedo needle jumps.
Second. The indication is no doubt wrong.

I would like to know if someone has experience or knowing of this circuit.
Any idea to found the electric diagram ?

How much influence has the resistor value ? And the DC gain of the
transistor ? 
Is there a way to correct the indication ?

The DC motor drains 50 mA max after the cleaning and lubrication.

The instruments are the Veglia type. The car a 33 16v '92.

Any advice will very appreciate.

Thanks in advance
Norberto
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