8280 Drive - Service Manual / FD1797B-02

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8280 Drive - Service Manual / FD1797B-02

vossi
Hello,
I downloaded all from Zimmers and I found a WD catalog with all datasheets
in the web.
But nowhere is an information about version A and B of the 1797!
It's not the speed grade! All 1797 are 2MHz chips. The 1MHz controllers have
different WD-numbers.

I can get 1797-PL and 1797A-02 at ebay - but no 1797B! is it
interchangeable?
The 1797B looks different - it has a black painted windows at the top - like
an UV-eprom - I think its factory programmed?

Also I cannot find a service manual of the 8280. My drive has an error code
(5 times blinking). In the 8250 its a zero page fault (6532) - but changing
both 6532 has no change...

Christian  



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Re: 8280 Drive - Service Manual / FD1797B-02

vossi
I found the solution!

At the 1791 controller datasheet on the last page you see this:
A = ceramic
B = plastic

At ebay I found 1797A-02 - thats the better ceramic version of B-02 and I
found chips 1797-PL - thats the new name for the 1797B with the usual
P=plastic!

<http://cbm-hackers.2304266.n4.nabble.com/file/t374762/Bildschirmfoto_2018-04-24_um_07.png>



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Re: 8280 Drive - Service Manual / FD1797B-02

Rob Clarke
Right. I also came to the same conclusion, and bought those same from
ebay and they worked fine. There is no service manual for the
controller, but there is for the TMS848-02 drive mechanisms.

I also disassembled the ROM in order to get mine working and even
resorted to making my own custom ROM's to diagnose the problem, using
various combinations of the 3 LED's to track it down. If I can find my
disassemblies I will confirm the meaning of 5 flashes.

cheers, Rob


On 24/04/2018 07:52, vossi wrote:

> I found the solution!
>
> At the 1791 controller datasheet on the last page you see this:
> A = ceramic
> B = plastic
>
> At ebay I found 1797A-02 - thats the better ceramic version of B-02 and
> I
> found chips 1797-PL - thats the new name for the 1797B with the usual
> P=plastic!
>
> <http://cbm-hackers.2304266.n4.nabble.com/file/t374762/Bildschirmfoto_2018-04-24_um_07.png>
>
>
>
> -----
> greets
> Christian
> --
> Sent from: http://cbm-hackers.2304266.n4.nabble.com/

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Re: 8280 Drive - Service Manual / FD1797B-02

Rob Clarke
I found it. 5 flashes indicates a fault with the 6810 128-byte static
RAM at position 4D.

cheers, Rob


On 24/04/2018 14:51, Rob Clarke wrote:

> Right. I also came to the same conclusion, and bought those same from
> ebay and they worked fine. There is no service manual for the
> controller, but there is for the TMS848-02 drive mechanisms.
>
> I also disassembled the ROM in order to get mine working and even
> resorted to making my own custom ROM's to diagnose the problem, using
> various combinations of the 3 LED's to track it down. If I can find my
> disassemblies I will confirm the meaning of 5 flashes.
>
> cheers, Rob
>
>
> On 24/04/2018 07:52, vossi wrote:
>> I found the solution!
>>
>> At the 1791 controller datasheet on the last page you see this:
>> A = ceramic
>> B = plastic
>>
>> At ebay I found 1797A-02 - thats the better ceramic version of B-02
>> and I
>> found chips 1797-PL - thats the new name for the 1797B with the usual
>> P=plastic!
>>
>> <http://cbm-hackers.2304266.n4.nabble.com/file/t374762/Bildschirmfoto_2018-04-24_um_07.png>
>>
>>
>>
>> -----
>> greets
>> Christian
>> --
>> Sent from: http://cbm-hackers.2304266.n4.nabble.com/

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Re: 8280 Drive - Service Manual / FD1797B-02

Ethan Dicks
On Tue, Apr 24, 2018 at 8:57 AM, Rob Clarke <[hidden email]> wrote:
> I found it. 5 flashes indicates a fault with the 6810 128-byte static RAM at
> position 4D.

That makes sense for a zero page RAM fault (common to see a 6810 in
that era holding zero page and the stack).

-ethan

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Re: 8280 Drive - Service Manual / FD1797B-02

vossi
OK, thanks,
in the 8250 5 flashes is also zero page fault - but at the first cpu - the
zero page in the 6532's.
I tried another 6810 but I have only non-A variant for 1MHz - the 68A10 is
for 1,5 MHz.
I think the A is already a little bit too slow and my non-A is really too
slow.

Please send me your disassemblies and the rom images - so I can compare them
to my.
email: [hidden email]

greets
Christian



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Re: 8280 Drive - Service Manual / FD1797B-02

vossi
I just tested the 68A10 and my spare 6810 in my Atari 1050 and they are all
OK.
If I pull the controller cpu 6502 the led is permanent on.
I have to check the controller 2716-ROM and I have to wait for my new
fdc-ic.

Christian



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Re: 8280 Drive - Service Manual / FD1797B-02

vossi
Thanks to Rob I found the error at the RAM from 2000-2FFF and replaced both
2114.
Now the drive has no flash code anymore.
I can access to it with my 8032sk.
But if I try to format with the header command it always gives me a "bad
disk".
I tried both drives and different discs (DS, DD, soft sectored).
The errorcode says number 26 = write protect - but all disks (some new ones)
have no hole = write enabled!

Any Ideas?

Christian



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Re: 8280 Drive - Service Manual / FD1797B-02

Francesco Messineo
On Tue, Apr 24, 2018 at 10:47 PM, vossi <[hidden email]> wrote:
> Thanks to Rob I found the error at the RAM from 2000-2FFF and replaced both
> 2114.
> Now the drive has no flash code anymore.
> I can access to it with my 8032sk.
> But if I try to format with the header command it always gives me a "bad
> disk".
> I tried both drives and different discs (DS, DD, soft sectored).
> The errorcode says number 26 = write protect - but all disks (some new ones)
> have no hole = write enabled!

I would look at the sensors for the write protect hole and see if they
work and follow the signals until they reach an input
pin.
I have never seen a real 8280 of course... just guessing.

Frank

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Re: 8280 Drive - Service Manual / FD1797B-02

Rob Clarke
You're welcome.

They are branded as DS, DD? The original ones I bought on evilbay were
sold as DS, but were in fact SS. The difference is just a few degrees
difference in where the index hole is. To answer your PM here, yess - it
works fine on an 8032 using the 'HEADER' command and no special
parameters were needed.

When it does format it takes a long time and is a two pass process. On
the first pass it clicks through at about a track a second and just
writes 00 to every sector. On the second pass I think I read it scans
for bad sectors but takes about 10-15 seconds per track. The entire
process takes around 20 minutes to format a disk. Here's a screenshot I
had lying around from formatting a 8280 disk from a 610.

http://inchocks.co.uk/commodore/format_disk2.jpg

I seem to remember that even when I got decent disks, it took quite a
lot of effort to get the drives functional. I replaced a couple of
transistors, a blown fuse (which can safely be jumpered on the 848-02's,
they were ommited from later models.) I think a lot of the black axial
ele-capacitors and the yellow ones around the speed control area were
out of spec. Nevertheless, given the symptom you describe, i'd also be
checking the connectors to the sensors, they were a bit grubby on mine.

cheers, Rob


On 24/04/2018 23:03, Francesco Messineo wrote:

> On Tue, Apr 24, 2018 at 10:47 PM, vossi <[hidden email]> wrote:
>> Thanks to Rob I found the error at the RAM from 2000-2FFF and replaced both
>> 2114.
>> Now the drive has no flash code anymore.
>> I can access to it with my 8032sk.
>> But if I try to format with the header command it always gives me a "bad
>> disk".
>> I tried both drives and different discs (DS, DD, soft sectored).
>> The errorcode says number 26 = write protect - but all disks (some new ones)
>> have no hole = write enabled!
> I would look at the sensors for the write protect hole and see if they
> work and follow the signals until they reach an input
> pin.
> I have never seen a real 8280 of course... just guessing.
>
> Frank
>


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Re: 8280 Drive - Service Manual / FD1797B-02

vossi
OK,
write protect goes directly to the 1797 - maybe its not ok.
I think that not both sensors are broken...
I will connect my LA to the complete shugart bus and check all signals.

Christian




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Re: 8280 Drive - Service Manual / FD1797B-02

vossi
OK,
it was my mistake - I didn't realized that the new diskettes are write
protected!!!
Now I taped the small notch and was able to format disks in both drives.

Drive 0 formatted disk is readable in both drives, but drive 1 formatted
disks is only readable in this drive.
I think I have to clean both drives and heads...

Interesting note:
Both new Memorex 2s2d flex disks have 3944 blocks free.
The used Maxell FD2-XD 2s2d disk has 3945 blocks free - why ???



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Re: 8280 Drive - Service Manual / FD1797B-02

MiaM
Den Thu, 26 Apr 2018 10:05:06 -0700 (MST) skrev vossi <[hidden email]>:

> OK,
> it was my mistake - I didn't realized that the new diskettes are write
> protected!!!
> Now I taped the small notch and was able to format disks in both
> drives.
>
> Drive 0 formatted disk is readable in both drives, but drive 1
> formatted disks is only readable in this drive.
> I think I have to clean both drives and heads...
>
> Interesting note:
> Both new Memorex 2s2d flex disks have 3944 blocks free.
> The used Maxell FD2-XD 2s2d disk has 3945 blocks free - why ???

Formatted with different firmware? (Like 2040 v.s. 3040/4040)

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Re: 8280 Drive - Service Manual / FD1797B-02

Rob Clarke
In reply to this post by vossi
I think the second pass of the format looks for, and marks, bad blocks.
A disk that has all sectors marked good should have 3946 blocks free on
an 8280.

Rob

On 26/04/2018 19:05, vossi wrote:

> OK,
> it was my mistake - I didn't realized that the new diskettes are write
> protected!!!
> Now I taped the small notch and was able to format disks in both drives.
>
> Drive 0 formatted disk is readable in both drives, but drive 1 formatted
> disks is only readable in this drive.
> I think I have to clean both drives and heads...
>
> Interesting note:
> Both new Memorex 2s2d flex disks have 3944 blocks free.
> The used Maxell FD2-XD 2s2d disk has 3945 blocks free - why ???
>
>
>
> -----
> greets
> Christian
> --
> Sent from: http://cbm-hackers.2304266.n4.nabble.com/
>