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Atari Diskdrive 810


Martin72

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I have bought recently a 810 diskdrive. The diskdrive is complete and the case is in good condition. When i connected the drive to my computer the following happens:

- the Atari computer recognize there's a drive

- the led on the drive illuminates

- the diskette spins continuous

- the head don't move but once in the let say 10 seconds there's a strange sound audible at the stepmotor (it seems that the drive tries to move the head beyond the maximum (or minimum) position).

 

I dowloaded the Service manual and i see a difference with this drive. In the socket of A105 of the Side 810 pcb there's another pcb with Atari code CO177227. Do someone know what the meaning is of this pcb? At this PCB there's the FD1771B disk controller at socket A203. Can someone help me with a circuit diagram of this pcb?

I have attached a picture of the 2 pcb's.810sidepcb.jpg

Edited by Martin72
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The second PCB contains the disk controller chip (the FD1771B) and it's supporting circuitry. You can find the schematics here:

 

http://www.jsobola.republika.pl/schematy.htm

 

Note that this board doesn't control the movement of the head stepper, this is done directly from the IO port on the 6532 chip in socket A104.

 

When you hear the sound from the stepper motor is the head already at the start of end of it's travel? If it is, I would turn off the drive and manually move the head to somewhere in the middle then turn the drive back on and see if it moves the head to the end of it's travel. Note that the 810 doesn't have anything that senses whether the head is at the start or end of the travel. When the drive is turned on it just tries to move it for a period of time to be sure it's as far as it can go.

 

If the drive can't move the head then it could be a problem with the 6532, the +12V from the power supply, transistors Q106-Q109 or diodes CR101 - CR104.

 

Dan

Edited by DanBoris
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When i turn off the 810 and manually move the head to another position and then turn on again, the head moves to the same old (maximum or minimum) position again.

Thanks for the link to the diagrams. I see there are 2 possibilities: FD1771 in A105 or FD1771 on PCB CO17227. Do you know what the meaning is of this auxiliary pcb?

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When i turn off the 810 and manually move the head to another position and then turn on again, the head moves to the same old (maximum or minimum) position again.

Thanks for the link to the diagrams. I see there are 2 possibilities: FD1771 in A105 or FD1771 on PCB CO17227. Do you know what the meaning is of this auxiliary pcb?

Martin,

 

Perhaps overlooking the obvious, but are you sure you fed it a proper disk? It has to a double density disk, high density (1,2 Mb) won't work. Besides that the 810 (in standard form) can only read single density disks, enhanced or double density are only feasible by installing a Happy 810 or similar enhancements. If possible, try again with a freshly formatted SD disk that contains DOS.

 

Groeten,

 

re-atari

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Besides that the 810 (in standard form) can only read single density disks, enhanced or double density are only feasible by installing a Happy 810 or similar enhancements.

 

I don't think that the Happy 810 let you use double (or enhanced) density.

 

I don't know if there were any 810 upgrades that let you, but adding double/enhanced density in the 810 would require replacing the FDC and some of its related analog logic. The FDC in the 810 is FM only, no MFM support.

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I have bought recently a 810 diskdrive. The diskdrive is complete and the case is in good condition. When i connected the drive to my computer the following happens:

- the Atari computer recognize there's a drive

- the led on the drive illuminates

- the diskette spins continuous

- the head don't move but once in the let say 10 seconds there's a strange sound audible at the stepmotor (it seems that the drive tries to move the head beyond the maximum (or minimum) position).

 

I dowloaded the Service manual and i see a difference with this drive. In the socket of A105 of the Side 810 pcb there's another pcb with Atari code CO177227. Do someone know what the meaning is of this pcb? At this PCB there's the FD1771B disk controller at socket A203. Can someone help me with a circuit diagram of this pcb?

I have attached a picture of the 2 pcb's.

 

That extra board has the floppy controller chip and hardware data separator. The early versions of the floppy chips didn't have built in data separator.

This includes the 1771 as used in the 810 and the 179X series as used in the ATR8000 (any others?). The 279X series as used in the 1050, Indus and the 1770,1772,1773 (XF551) does have a data separator built in and is adjusted with a variable cap (279X series).

The early 810's didn't have the data separator and the floppy controller was plugged directly into that socket.

How does the data separator work? I am not really sure. the 810 field service manual has several wave forms from different sections of the data separator.

That noise you hear is the head banging against a stop to make sure the head is positioned at track zero. It keeps doing that because for some reason, the drive cannot read the disk.

Is the head clean? does your 810 have a top board that the head plugs into? Pulled all plugs and re seated them?

 

James

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That extra board has the floppy controller chip and hardware data separator. The early versions of the floppy chips didn't have built in data separator.

This includes the 1771 as used in the 810 and the 179X series as used in the ATR8000 (any others?). The 279X series as used in the 1050, Indus and the 1770,1772,1773 (XF551) does have a data separator built in and is adjusted with a variable cap (279X series).

The early 810's didn't have the data separator and the floppy controller was plugged directly into that socket.

How does the data separator work? I am not really sure. the 810 field service manual has several wave forms from different sections of the data separator.

That noise you hear is the head banging against a stop to make sure the head is positioned at track zero. It keeps doing that because for some reason, the drive cannot read the disk.

Is the head clean? does your 810 have a top board that the head plugs into? Pulled all plugs and re seated them?

 

James

 

James, thank you for your clear explanation of the additional pcb in this drive. It was not clear for me what the purpose is of this pcb.

Indeed, the head is banging against a stop, but this happens also when there's no diskette in the drive after power on. So there's something wrong, and i will check this out after my holiday.

Regards,

Martin

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That extra board has the floppy controller chip and hardware data separator. The early versions of the floppy chips didn't have built in data separator. This includes the 1771 as used in the 810 ...

The early 810's didn't have the data separator and the floppy controller was plugged directly into that socket.

 

Actually the 1771 does have an integrated data separator. But it is a very simple one, not too reliable. For this reason the 1771 could be configured to optionally, use an external data separtor.

 

The 810 designers assumed the 1771's internal data separator would be good enough, and the original design didn't include an external one. This design is the one you see in the Field Service Manual.

 

It turned to be not too reliable. So later drives include a daughter-board with an external separator circuit.

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Actually the 1771 does have an integrated data separator. But it is a very simple one, not too reliable. For this reason the 1771 could be configured to optionally, use an external data separtor.

 

My field service manual includes the external data separator at the end of the book with the noted wave forms.

 

James

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My field service manual includes the external data separator at the end of the book with the noted wave forms.

 

I was talking about the FSM that was recently uploaded here, the one that Martin72 downloaded. It doesn't cover the later 810 versions with external data separator.

 

You obviously have a newer/updated version of the FSM.

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My field service manual includes the external data separator at the end of the book with the noted wave forms.

 

I was talking about the FSM that was recently uploaded here, the one that Martin72 downloaded. It doesn't cover the later 810 versions with external data separator.

 

You obviously have a newer/updated version of the FSM.

 

Ahhhhh. I sit corrected. :)

 

I should point out that my field service manual is by the looks a 2nd (at least) generation photocopy.

There was a lot of that here in australia and most likely in other countries.

Even my old action cart is a copy of an original 2 eprom version.

 

James

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That extra board has the floppy controller chip and hardware data separator. The early versions of the floppy chips didn't have built in data separator.

This includes the 1771 as used in the 810 and the 179X series as used in the ATR8000 (any others?). The 279X series as used in the 1050, Indus and the 1770,1772,1773 (XF551) does have a data separator built in and is adjusted with a variable cap (279X series).

The early 810's didn't have the data separator and the floppy controller was plugged directly into that socket.

How does the data separator work? I am not really sure. the 810 field service manual has several wave forms from different sections of the data separator.

That noise you hear is the head banging against a stop to make sure the head is positioned at track zero. It keeps doing that because for some reason, the drive cannot read the disk.

Is the head clean? does your 810 have a top board that the head plugs into? Pulled all plugs and re seated them?

 

James

 

Isn't the Data Separator Board also known as the "Grass Valley Upgrade?" Judging from other 810 owners, this board made a lot of difference in reliability. I seem to recall that among other things the drive speed variation with the new board was improved. (?)

 

-Larry

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