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Tractorfan · 19th Sep 2017, 10:04 pm

Hi,
I 'scoped the three 'phases' and one appears to have a different (smaller and more 'rounded') waveform to the other two. I've tried substituting the transistors one-by-one except the output ones inside the heatsinks as I have nowt like them in my bit box.
I removed the motor and metered the windings and the rotating contacts (for the want of a better description), and it all looks OK.
But still the motor will only start when in a certain part of its rotation.
The circuit looks broadly similar to the Grundig and is shewn in an earlier post.
Cheers, Pete.

19th Sep 2017, 10:04 pm	#17
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Re: Old Uher 4000 motor problem. Hi, I 'scoped the three 'phases' and one appears to have a different (smaller and more 'rounded') waveform to the other two. I've tried substituting the transistors one-by-one except the output ones inside the heatsinks as I have nowt like them in my bit box. I removed the motor and metered the windings and the rotating contacts (for the want of a better description), and it all looks OK. But still the motor will only start when in a certain part of its rotation. The circuit looks broadly similar to the Grundig and is shewn in an earlier post. Cheers, Pete. Attached Thumbnails __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..." Last edited by Tractorfan; 19th Sep 2017 at 10:15 pm.