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XF551 Update

XF551s

I’ve resisted updating for the last couple of weeks.  Partly out of depression and partly out lack of time.  Lets get the bad news out of the way right now.  It’s a mixed bag, but there is some hope.

As I last reported the power supply seemed to be working and no fizzes, blue/black smoke or loud bangs to signal fatal failure.  I then proceeded to make the power and data cables to go from board to drive housing.  I verified pin to pin as best I was able to that my cables matched and mated with the originals.   As I placed them on the board it became apparent that some design assumptions would have to be changed.  Nothing fatal, just some more research and parts sourcing.

Then I placed the board into the case.   The fit of the board in the case is near perfect.  A tiny adjustment here and there and that part of the project is done.

DSC_1715M    DSC_1716M

Then I fitted the drive housing on it’s piers.  It fit and layed flat, but I could see barely a few mils between the OS chip in its socket and the bottom of the drive housing.    The bottom of the drive housing is not filled flat.  There are large open spaces around the spindle and drive motor so depending on the height of the other parts not installed yet I could have a fit issue between the board and the drive housing.  Or not.  Certainly something to think about.

After connecting the power and data cables I was ready for the acid test so to speak.  Would the drive/new board behave as the original?  Remember there is no connection to a Atari computer at this point yet.  I tested first the reaction of an original drive with only power applied as a gauge.    The power light comes on briefly and the motor seems to spin up and then come to rest, the power light goes off.  If I could get my board to do the same, then I could proceed to the next step of checking SIO signals from the connector to see if there was any danger of foreign voltage on the connector.

I pressed the power switch on.

The power light came on and the drive spun up.  And kept on spinning and spinning and spinning.  The light stayed on.

I turned the power switch off.

At least the power switch worked.  The power light went out and the drive stopped spinning.  Conclusions were that yes I had the power cable right.  But I couldn’t say for sure much else was right.  Two areas I began to investigate– 1) reexaming the board schematics to see if I had pins connecting to the wrong part (I swear I am beginning to see these schematics in my sleep) and 2) data cable mismatch.  I found errors in both.  The data cable I could fix immediately but I had run multiple pins to the wrong parts.  Perhaps a hold over from the Eagle design days.  That was not so easily fixed.

Coupled with other design changes I intended to make I decided to make one more proto board.  That new board should arrive next week.  Look for an update around the first week or two in March.

PS Feb 25 — The protoboard arrived today.  Along with the first proto of the front panel board for the led display and drive select etc.  I probably won’t come up for air for at least the next two days or so.

 

 

 

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