Weird disk writing problem

[Cluster]

Hi.

I have two FDS drives. Both are not write protected (one initially uprotected, one modded). Both can read original licensed disks without any problems.

But something weird happens when I'm writing disks. When I write disk using the first FDS drive it works great on the same drive. But the second FDS drive can't read it! And vise-versa: disk written on the second drive is not working on the first. Error 22 or error 27 appears.

I tried the Disk Keeper, Disk Hacker II and my Dumper/Writer (https://github.com/ClusterM/famicom-dumper-writer) with RAM adapter - result is always the same.

At first I through that it's some calibration problem of one of the drives, but I found third FDS drive and it also can't read disks written by the first and second drives.

I tried to read disk using RAM adapter and dumper: CRC error on first block (disk header block). First few bytes are ok and garbage data follows.

What can be wrong? Why is this happening?

[ericj]

Have you tried with a one-sided game like SMB, using the same RAM adapter for each drive when testing?

[Cluster]

Have you tried with a one-sided game like SMB, using the same RAM adapter for each drive when testing?

Yes, i did. I've used the same RAM adapter all the time.

[SteveP256]

Have you tried making disk images and comparing the 3 disk images. Try a loading them in a hex editor and see if they are showing the same data, but the bits are shifted.

Example
Drive 1 shows 10111011
Drive 2 shows 01011101
Drive 3 shows 00101110

Or see if you see *NINTENDO-HVC* at the same area on the images

[Cluster]

Have you tried making disk images and comparing the 3 disk images. Try a loading them in a hex editor and see if they are showing the same data, but the bits are shifted.

Example
Drive 1 shows 10111011
Drive 2 shows 01011101
Drive 3 shows 00101110

Or see if you see *NINTENDO-HVC* at the same area on the images

Data is corrupted after "*N" and i can't see any patterns.

[SteveP256]

Do the drives both appear to run at the same motor speed? Possibly the speed differ between the drives. I have two drives here one that I replaced the belt that can write (no mod) and one that I had to mod to write disks. At first the modded one would not read any disks written with the first drive. It would give error 27 every time.

What I did was adjust the motor speed (at the top of the motor). Use very very small adjustments. Each time try booting a written disk, then a original copy of a game.  It takes a long time to get both drives to read each others disks, but now both my drives can read the others disk.

[Cluster]

Use very very small adjustments. Each time try booting a written disk

I tried to write disk on the second drive and ajust speed on the first drive in this way. Without any success

[SteveP256]

Hmm, I still think that it is a motor speed issue. When I was adjusting my drive I turned the motor potentiometer all the way right or left, then turned it to the half way point. If I turned it too far left it would give error 22 every time reading a disk, too far right would give error 27. Keep trying to read original disks until you see the Nintendo text scrolling up. Getting the correct motor speed is a major pain to do, took me several hours.

If you have a spare famicom and ram adapter, you could run both at same time with same copy of disk.  Then you can visually see if the speed differs 

[ericj]

If you have a game doctor and the copy master program you can read the drive speed when you adjust it.

[Cluster]

I tried to tune motor speed of the first FDS drive without any success.

Then I decided to try a very unusual solution. I erased disk using neodymium magnet. Then I writed it on the second FDS drive and the first drive reads it without any problems now! This method works 100% of the time for any disk and any game when I'm writing on the second drive.

But this method only works partially when I write disks on the first drive - second drive fails while reading long blocks (large files), CRC check fails.

So I don't know if the second drive is good at writing or the first drive is good at reading. And it's still weird that I need to use magnet every time.

[Tomy]

Hi Cluster,

After belt replacement, five things you need to take care.

1) Spindle Hub Alignment. It is very important.
2) Check Head Adjustment Screw (Original no need to tune). If it tuned by someone, you may need to tune it again.
3) Drive speed (I use Game Doctor's Copy Master drive speed test, speed should be 5 without disk insert)
4) Pressure cotton on the magnet head can not be too thin.
5) Clean the magnet head.

Most problem is 1) or 2), if Spindle Hub is not at right position or Head Adjustment Screw tuned at wrong place. Then the copied disk only can read by the drive which copy it.
You can read here : https://www.famicomdisksystem.com/tutorials/fds-repair-mod/belt-replacement-adjustment/

Last, you should have some original disk for test.

Hope this help.

[ericj]

How are your drives modded for writing and which chips (7201 or 3206) and power board revisions do they have?

[Cluster]

1) Spindle Hub Alignment. It is very important.

Seems like it's aligned very well on both drives. This way:

2) Check Head Adjustment Screw (Original no need to tune). If it tuned by someone, you may need to tune it again.

I haven't touched it and seems like nobody adjusted it. There is red glue all around the screw on both drives.

3) Drive speed (I use Game Doctor's Copy Master drive speed test, speed should be 5 without disk insert)

I tried to change the speed of the first drive so that it reads a floppy disk written by the second drive, without any success. Both drives can read original disk without any problems.
I tried to write Copy Master to disk but FDS can't run it without Disk Doctor. I can't understand how to use it. Can I download Disk Doctor ROM somewhere or I need some extra hardware?

4) Pressure cotton on the magnet head can not be too thin.

I'll check it.

5) Clean the magnet head.

I will do it, thanks.

You can read here : https://www.famicomdisksystem.com/tutorials/fds-repair-mod/belt-replacement-adjustment/

I read it already.

Last, you should have some original disk for test.

Original disk works perfectly on both drives for reading and writing. Also game saved on the first drive works perfectly on the second one.

How are your drives modded for writing and which chips (7201 or 3206) and power board revisions do they have?

The first drive has a FMD-POWER-03, it has not any protection (see https://www.famicomworld.com/forum/index.php?topic=15024.0) and a 7201.

The second drive has FMD-POWER-04, it's modded by me using this guide: https://famicomworld.com/workshop/tech/fds-power-board-modifications/. And it has a 7201 too.

[Tomy]

Hello Cluster,

Last thing I want to ask is, the disk you use to clone/write is original disk ? If it is not original, then the copied disk may only can read by the drive which copy it.

Seems, you do all the things from my post above. Then I have no idea what is the problem now.

If you can fix your problem, I want to know it too. Thanks.

[Cluster]

Hello Cluster,

Last thing I want to ask is, the disk you use to clone/write is original disk ? If it is not original, then the copied disk may only can read by the drive which copy it.

Seems, you do all the things from my post above. Then I have no idea what is the problem now.

If you can fix your problem, I want to know it too. Thanks.

Seems like those disks are original or rewrited original.
You cannot see attachments on this board.

Can you help me with Copy Master? Can I write it on disk using dumper/writer or I can't run it without extra hardware?

Also I will receive more FDS drives soon for tests.