[fdutils] Need help with weird floppy issue

Uwe Teetz mhteetz at aon.at
Wed Mar 8 18:56:48 CET 2006

Hi Donnie,

I found an even better solution, put an AM (455kHz) LC IF filter and a capacitor in place of the ceramic resonator. Mine worked fine, adjustable from 400 to 600 kHz the motor following the in speed.

If you recycle a filter from an old radio, look to it from the bottom, it should have a capacitor build in and connected to two of the mostly five pins. Use those two. Very common are the outer two pins on the side with three pins.

I will do some testing with the floppymeter later on.


----- Original Message ----- 
  From: Donnie Barnes 
  To: Uwe Teetz 
  Sent: Wednesday, March 08, 2006 3:19 PM
  Subject: Re: [fdutils] Need help with weird floppy issue

  On 3/8/06, Uwe Teetz <mhteetz at aon.at> wrote:
    Hi Donnie,

    to the motor speed:

    the 3 phase syncron motor controller has a ceramic resonator as reference -> nothing to adjust.

    Many of my drives here use 492kHz and 491kHz resonator. This slight difference will not help. For testing I removed the resonator and feed to one pin a signal from an extern oscillator with 1V~ output (you have to try which one is the input to the controller) See pic2. I could regulate the motor from half to double speed easily.

    You could also try to replace the ceramic resonator wit a 455kHz resonator used as IF filter in AM radio receiver or put one small RC oscillator in to the case. RC oscillator (potentiometer adjustable) samples are plenty in the net.

  I've got a pretty crappy (compared to yours) signal generator that may do what I need.  If not, I can certainly build an RC oscillator.  Looks like you had yours set to sine wave, but I suppose I'll take a peek at the signal off the oscillator on the device with an oscope.  I assume I just need to do floppy access on the PC to make it spin, right?  

  Thanks for the great info!


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