Repair diary Sinclair C5 - Page 3:

Friday, 24. April 2009:

Exhumation of a motor

Released the steering bar with a hammer and finally removed the body.
Removing steering bar

More drastic methods.

Opened the motor control box and found some bugs. Literally.
But scared from my threatening with a screwdriver they fled instantly.
Removed the body

Removed the body. A view to the chassis.

Everything dirty here

Yuck! Dirty! Dirty! Dirty!

By the way: it was not the motor making buzzing noises but the relay.
Also found the reason: the 2k2 resistor R1 was burnt-out.
The motor doesn't make anything. Even if connected directly with 12V. Therefore I disassemble it.
Aplenty of dust, dirt and spider nests on and inside the motor. Looks like exhumed.
Grease and dirt joined to a ropy compound inside the gearbox.

Saturday, 25. April 2009:

Let there be light!

Motor and gearbox cleaned, sanded the rust, all parts greased and reassembled.
No idea what the problem actually was - but now the motor runs again.
Gearbox before


Gearbox after

... and after.

LED display

And the Lord said "Let there be light!" And there was light. Or something like this...

Motor control still not working. Obtained spare parts and replaced the LM358 OPV.
A 2A 7805 voltage regulator follows the original LM342 (you must replace R1 by a wire jumper for this). Now the LED display is working at least.
Unfortunately the relay is still not working.

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