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Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Thu Mar 14, 2019 2:48 pm
by nightson
Hi I'm dumping an Amiga game called Chip's Challenge. My Samsung SFD-321B /LHSE REV. T6A and SFD-321B /LEB REV. T5 encountered weird bad sectors at different positions in some attempts, while TEAC FD-235HF got good dumps consistently. However, all dumps output ADF images with the same hash. Could someone explain to me how this is even possible? Thanks!

TEAC FD-235HF(82 Tracks):

1st try:
http://imgur.com/kiwZTti

2nd try:
https://i.imgur.com/dbHzARy.jpg

3rd try:
https://i.imgur.com/3cQ6aO1.jpg

Samsung SFD-321B /LHSE REV. T6A (84 Tracks)

1st try:
https://i.imgur.com/3WWK12Q.jpg

2nd try:
https://i.imgur.com/KwqRE5I.jpg

3rd try:
https://i.imgur.com/QAxFx7I.jpg


4th try:
https://i.imgur.com/HBF6ypN.jpg

Samsung SFD-321B /LEB REV. T5 (84 Tracks)

1st try:
https://i.imgur.com/HEAEurE.jpg

2nd try:
https://i.imgur.com/zk5rAkN.jpg
https://i.imgur.com/QqXa9ll.jpg

link to all the dumps, sorry for the really messed filenames :P :
https://mega.nz/#!ohFFSKRB!AXfibgxxCaw_ ... uGZddJjrD0

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Thu Mar 14, 2019 6:23 pm
by brightcaster
For me it looks, as if there are certain tracks not perfectly index alligned with the panasonic drives. The HxC analyzer marks them red while dtc still creates valid adfs because it doesn't need them perfectly alligned.

Still the teacs don't behave this way and read the index pulses in line. Is there any chance of an LED lamp on your desk misleading the index sensor sometimes? I don't think that it is flutter because it is not affecting the speed as far as I can see it but only the position of the index.

David

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Fri Mar 15, 2019 7:59 am
by nightson
brightcaster wrote:
Thu Mar 14, 2019 6:23 pm
For me it looks, as if there are certain tracks not perfectly index alligned with the panasonic drives. The HxC analyzer marks them red while dtc still creates valid adfs because it doesn't need them perfectly alligned.

Still the teacs don't behave this way and read the index pulses in line. Is there any chance of an LED lamp on your desk misleading the index sensor sometimes? I don't think that it is flutter because it is not affecting the speed as far as I can see it but only the position of the index.

David
I don't have a LED lamp near my desk so that's not the problem. The thing is that this problem only occurs with this particular disk. I don't have access to other Amiga games at the moment but I tried dumping the DOS version of Inca which has 10 disks. All the disks were read without any error by the Samsung SFD-321B REV. T6.

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Fri Mar 15, 2019 11:02 am
by ZrX
I just checked all the dumps with my own tool and every one of them was nice and clean. No bad sectors or misalignments visible.

The issue is most likely the HxC analyzer making a mistake with the data of those few tracks.

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Fri Mar 15, 2019 11:10 am
by brightcaster
Could it bee that the cookie slightly stucks in the sleeve while passing the index hole?

David

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Sat Mar 16, 2019 11:00 am
by brightcaster
Actually the panasonics give two index pulses (first is 4ms to early) on certain tracks, which confuses HxC but not DTC...

David

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Sat Mar 16, 2019 7:02 pm
by nightson
ZrX wrote:
Fri Mar 15, 2019 11:02 am
I just checked all the dumps with my own tool and every one of them was nice and clean. No bad sectors or misalignments visible.

The issue is most likely the HxC analyzer making a mistake with the data of those few tracks.
Thanks! Is your tool publicly available?

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Sat Mar 16, 2019 7:09 pm
by nightson
brightcaster wrote:
Sat Mar 16, 2019 11:00 am
Actually the panasonics give two index pulses (first is 4ms to early) on certain tracks, which confuses HxC but not DTC...

David
How did you check that? Is that normal behavior or faulty?

By the way, why do you keep calling my Samsung drive Panasonics...

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Sat Mar 16, 2019 7:30 pm
by brightcaster
How did you check that? Is that normal behavior or faulty?
You can see it in the track view mode if you use the HxC tool. For example on track 63 side 1 of the SFD-321-T6_1 stream. Look at the blue line on top of the view where after sector 11 there are two pulses befor sector 1 starts again. On other tracks (with no errors) there is only one pulse at this point.

You can measure the lenght of the pulse with the cursor showing the time at the x position of the status window. (Use the sliders at the bottom to zoom in.)

That is unusual and the first time for me seeing such a behavior.
By the way, why do you keep calling my Samsung drive Panasonics...
Uhhpps, I actually don't know ;-)

David

Re: Random bad sectors when dumping an Amiga disk with Samsung SFD-321B

Posted: Fri Mar 22, 2019 7:27 pm
by ZrX
nightson wrote:
Sat Mar 16, 2019 7:02 pm
ZrX wrote:
Fri Mar 15, 2019 11:02 am
I just checked all the dumps with my own tool and every one of them was nice and clean. No bad sectors or misalignments visible.

The issue is most likely the HxC analyzer making a mistake with the data of those few tracks.
Thanks! Is your tool publicly available?
Not at the moment. Dealing with different formats is still far from automatic.