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General Category => Amstrad CPC hardware => Topic started by: papichapo on 13:34, 22 March 21

Title: EME-150A at 670 rpm
Post by: papichapo on 13:34, 22 March 21
Hi all,
last summer, after almost 10 years, I've unpacked my old DDI-1 and plugged it to my 464. After having changed the belt, it was all okay  :D
Last week, I've made the same test but the noise motor was louder than expected.
After some investigations, I've found the motor was running at 670 rpm  :(
On the PCB, the VR201 cannot reduce this speed (just 1/2 rotation allowed).
Any clue ?
Title: Re: EME-150A at 670 rpm
Post by: tjohnson on 16:53, 22 March 21
normally there is a pot on the motor to adjust the speed.
Title: Re: EME-150A at 670 rpm
Post by: papichapo on 17:19, 22 March 21
No, I as said, on this model, the only way to adjust motor speed is by the way of a PCB pot, not on the motor.
And the tune is limited to 1/2 round, not enough to divide the speed limit by 2...
Title: Re: EME-150A at 670 rpm
Post by: Bryce on 17:46, 22 March 21
If the speed is anything above 350rpm, then it's not the pot that needs to be adjusted. It's usually a dry joint somewhere else on the PCB.

Bryce.
Title: Re: EME-150A at 670 rpm
Post by: papichapo on 20:06, 22 March 21
Does someone known what are current values am I supposed to find on the 4 wires solded to the motor : red, orange, yellow and brown... and of course where to check between...
The plug connecting to the PCB shows me correct values : I've 12 V (red wire) and 5 V (orange one).
Title: Re: EME-150A at 670 rpm
Post by: Bryce on 21:19, 22 March 21
The motor is a stepper motor, there won't be any stable voltage on any of the pins. It gets square waves sent to it from a driver IC.

Bryce.
Title: Re: EME-150A at 670 rpm
Post by: tjohnson on 12:08, 23 March 21
No, I as said, on this model, the only way to adjust motor speed is by the way of a PCB pot, not on the motor.
Actually just to be rather pedantic you didn't say that, you said "On the PCB, the VR201 cannot reduce this speed (just 1/2 rotation allowed)" you didn't mention the motor...
Title: Re: EME-150A at 670 rpm
Post by: papichapo on 15:07, 23 March 21
My apology, but I thought that giving the exact model of the drive in the topic title would have been enough to be understood...