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XF551 Mixed-Original Parts Bare PCBs

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You might have problems with the length. It's about 4 mm longer. The width seems close. The four pin layout looks close too.

 

The only way to know is to order it and see if it fits.

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I just noticed that the parts list has a WD1772ph disk controller. My 551 has a WD1770 disk controller. Does anyone know what the difference is?

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Are u sure?... That's great , because wd1772 is more difficult to get. So maybe we just need wd1770s

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I just noticed that the parts list has a WD1772ph disk controller. My 551 has a WD1770 disk controller. Does anyone know what the difference is?

 

I've never seen a WD1770PH in a XF551. :? There is a difference, but it is possible that that difference does not matter in the XF551. Atari may have gotten a sweet heart deal on the new floppy controller chips and that is why it was used. I have a WD1770PH chip and I'll try it in my XF551.

 

Edit:

 

Now I haven't done exhaustive tests, but using DOS 2.5 and an XF551 with one of my XF551 pcbs will format and read without problem. Other DOSs that may try to take advantage of the extra features of the XF551 may have a different response.

 

So provisionally I would have to say that a WD1770PH will work in place of a WD1772PH.

Edited by Dropcheck

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Update to using WD1770PH Chip:

 

While testing with the SF551 board I am finalizing I was unable to format a disk with either DOS2.5 or SpartaDOS 4.48 when the WD1770PH chip was installed. I was using Atari mode in SpartaDOS with normal skew, DD, 720 sectors with the drive selected as D2.. Using a normal 8MHz OSC. Now this is a SF314 3.5" drive mech . With the WD1772PH chip I had no problem. I will also check with the 8.333MHz OSC.

 

I will start more extensive testing with a normal 5.25" XF551 drive mech next.

 

Edit:

 

No change. WD1770PH will not work with the 3.5" board or drive mech.

Edited by Dropcheck

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I just noticed that the parts list has a WD1772ph disk controller. My 551 has a WD1770 disk controller. Does anyone know what the difference is?

 

Could you sent a high-res picture of your PCB with this FDC? And, additional wish, are you able to read out the EPROM/ROM? IMHO the 1770 can´t be used with different firmware, but I may be wrong.

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Update 2 to using WD1770PH Chip:

 

On a 5.25" XF551 with the WD1770PH chip installed I was able to get both SpartaDOS 4.48 and Atari DOS 2.5 to both boot, format and read and duplicate standard disks. Now I don't know about game disks that have some form of copy protection. I don't have any. So it may not be completely functional.

Edited by Dropcheck

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Update 2 to using WD1770PH Chip:

 

On a 5.25" XF551 with the WD1770PH chip installed I was able to get both SpartaDOS 4.48 and Atari DOS 2.5 to both boot, format and read and duplicate standard disks. Now I don't know about game disks that have some form of copy protection. I don't have any. So it may not be completely functional.

 

I hope someone can send you a few of those protected disks then, to make your test sequences even more useful.

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The 1770 IC had already been removed from the old PCB. I removed it to use on one of the new boards but now I think I will get a 1772. Best has them.

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it's okay that it has been removed, they want to see rom revs and pcb traces etc... want to see if anything else is different

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Update 2 to using WD1770PH Chip:

 

On a 5.25" XF551 with the WD1770PH chip installed I was able to get both SpartaDOS 4.48 and Atari DOS 2.5 to both boot, format and read and duplicate standard disks. Now I don't know about game disks that have some form of copy protection. I don't have any. So it may not be completely functional.

I found a datasheet that mentioned the WD1770 and WD1772 offer different step rates, likely the WD1770 has a step rate for the 360K 5.25" mechanism but not for the 720K 3.5".

 

This is mentioned on page 2 of the PDF at the following link.

https://datasheet.datasheetarchive.com/originals/distributors/Datasheets-115/DSAP002129.pdf

Edited by BillC

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sort of, the step rate is how fast it can step in ms, it just means going from track to track is slower or faster...

 

what might be an issue is having a track 0 or not...... but the sheet has an error and states the same nomenclature twice, I wonder which is which..

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If someone would come up with a way to use the USB powered 3.5 floppy in the 551, 354, or 314 case they would have an idea that might really have some sales potential. You could fit two of them into one 1050, 551, 314, or 354 case. You could probably even make it fit inside the case of a 1200XL.

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Here are some pictures of the PCB. The lettering on the PCB calls for a 1770. Another of my 551s has a 1772 but the PCB still calls for a 1770/

 

post-61328-0-99967600-1552359005_thumb.jpgpost-61328-0-85649500-1552359055_thumb.jpgpost-61328-0-60059700-1552358853_thumb.jpg

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Hmm.. from the FAQ:

 

Western Digital WD1772 Floppy Disk Controller (FDC) C026028

- Late production units substituted: Western Digital WD1770

 

Do all the silkscreens say 1770 yet it still had a 1772?

 

Also, the XF351 used a 1770.

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Hello kheller2

 

It's almost 2AM overhere, so I'm not gonna open up my intact XF551, but the PCB of the other XF551 that is laying around says 1770 on both sides, but has a 1772 in/on it.

 

Sincerely

 

Mathy

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I have just finished putting together a 551PCB with a 3.5 drive using the HYPER-B IC. Problem is that the drive won't read or format a disk. I know the disk is OK because I could read it and save to it with a PC. It is not an HD disk. I don't know if the problem could be my homebrewed ribbon cable or if the heads need cleaning. It looks like cleaning the heads could be a major operation. Can I do that through the disk opening or do I need to take the drive cover off. Any other troubleshooting ideas would be welcome.

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I have just finished putting together a 551PCB with a 3.5 drive using the HYPER-B IC. Problem is that the drive won't read or format a disk. I know the disk is OK because I could read it and save to it with a PC. It is not an HD disk. I don't know if the problem could be my homebrewed ribbon cable or if the heads need cleaning. It looks like cleaning the heads could be a major operation. Can I do that through the disk opening or do I need to take the drive cover off. Any other troubleshooting ideas would be welcome.

 

Does the drive respond to any disk commands? IE what kind of error are you getting?

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I have just finished putting together a 551PCB with a 3.5 drive using the HYPER-B IC. Problem is that the drive won't read or format a disk. I know the disk is OK because I could read it and save to it with a PC. It is not an HD disk. I don't know if the problem could be my homebrewed ribbon cable or if the heads need cleaning. It looks like cleaning the heads could be a major operation. Can I do that through the disk opening or do I need to take the drive cover off. Any other troubleshooting ideas would be welcome.

Have you tried hooking the drive to a PC and testing the drive?

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I have the drive set to drive 2, when I attempt to format drive two, the drive spins up and appears to be trying to perform an action and I get an error 144.

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