RD53 Restoration - test-drb@ccmp.vtda.org

19 May 2010

...
  -----Original Message-----
 From: cctalk-bounces at classiccmp.org [mailto:cctalk-
 bounces at classiccmp.org] On Behalf Of Rob Jarratt
 Sent: 19 May 2010 21:59
 To: 'General Discussion: On-Topic and Off-Topic Posts'
 Subject: RE: RD53 Restoration

  -----Original Message-----
 From: cctalk-bounces at classiccmp.org [mailto:cctalk-
 bounces at classiccmp.org] On Behalf Of Tony Duell
 Sent: 19 May 2010 20:25
 To: cctalk at classiccmp.org
 Subject: Re: RD53 Restoration

 > Could that be because the new boards are a different rev and  perhaps
  expect

 It's always possible. This is one reason why I really dislike
 board-swapping. It is much easier to repair a configuration that has
 worked once than one you don't know if it should work.

 I wonder if this drive depends on reading something from the platter  as
  ssonas the motor is up to speed (say a servo
pattern). if so, then if
 the
 heads are moved to far in or out , it may fail

 Did this drive suffer from the well-known 'sticky bumper' problem? If
 so,
 what have you done about it? Is it possible that if you just removed
 the
 old bumper that the heads are outside the servo area sometimes?

 Yes, this drive did have a sticky bumper. I resolved it by putting a
 very
 thin sliver of tape over the sticky bit. I did not loosen any bolts,
 but
 there is a bit of play in the heads when they are at rest and fully
 retracted.

 Regards

 Rob 
I have just put the original boards back in and powered up the drive twice.
I powered it up twice and both times the heads moved briefly. I used a
multimeter (it is all I have) to measure the voltage across the two leads to
the coil. The first time I noticed that the voltage briefly went to about
1.3V, the second time it was always 0V although it looked like the
multimeter may have noticed a change which was too fast for it.

I then tried a few more times and these times the voltage went to 1.3
immediately. Then when the heads moved it went to about 4V and after that it
went to 0V. So either I was measuring incorrectly the first two times, or
there is still something not right even when the heads do move.

Would be interested to know if anyone else sees these voltages. I have
another RD53 which I can dig out at the weekend to compare.

Thanks

Rob