A1200 df1: Ndos:

[Snoopy1234]

My A1200 is reporting NDOS: or Unreadable: on DF1: with 2 of the external drives I have. I've checked the resistors and cap at the external port with a meter and they're ok. I've run Amiga Test Kit and Drive test and there seems to be signals but as there's no guide on how to read the results IDK.
DF0: is a modified ALPS drive and working normally. When comparing DF0: and DF!: in ATK and DT the results seem to be in opposite directions.

[derSammler]

Originally Posted by Snoopy1234

DF0: is a modified ALPS drive and working normally.

That is most likely the issue. I have one A600 with a modified PC drive inside and guess what, it does not read disks from an external drive either. I guess while you can modify many PC drives, they still don't act exactly like an original Amiga drive, which means they don't play well with additional drives.

[Snoopy1234]

Originally Posted by derSammler

That is most likely the issue. I have one A600 with a modified PC drive inside and guess what, it does not read disks from an external drive either. I guess while you can modify many PC drives, they still don't act exactly like an original Amiga drive, which means they don't play well with additional drives.

Ok. That is really good to hear someone else has had the same experience.
The ALPS has been a good drive. I'm not sure if the mods include trackloader games. I had Chinon FZ-354's before but I blew 3 over a year or so.
Thanks.

[Nor Bert]

Originally Posted by Snoopy1234

My A1200 is reporting NDOS: or Unreadable: on DF1: with 2 of the external drives I have. I've checked the resistors and cap at the external port with a meter and they're ok. I've run Amiga Test Kit and Drive test and there seems to be signals but as there's no guide on how to read the results IDK.
DF0: is a modified ALPS drive and working normally. When comparing DF0: and DF!: in ATK and DT the results seem to be in opposite directions.

What interface are you using to connect external drives?

[Snoopy1234]

Originally Posted by Nor Bert

What interface are you using to connect external drives?

The DF1: rear port on the A1200 to a standard generic housed fdd or Gotek. They both run fine on other Amigas.

[Nor Bert]

What other Amiga did you test on?

Try command DISKCHANGE DF1:

Or

It is likely that the electronics for operating the external FDD port on this A1200 are faulty.

[Snoopy1234]

Originally Posted by Nor Bert

What other Amiga did you test on?

Try command DISKCHANGE DF1:

Or

It is likely that the electronics for operating the external FDD port on this A1200 are faulty.

Diskchange Df1: didn't change the situation.

Other than testing the external port resistors, cap; I'm not familiar with it.

Thanks.

[derSammler]

Since you say you have two external disk drives, take one out of the case and use it as the internal disk drive. You will immediately see if the modified PC drive is the culprit this way. No need to do any other guesswork before ruling this out.

[Snoopy1234]

Originally Posted by derSammler

Since you say you have two external disk drives, take one out of the case and use it as the internal disk drive. You will immediately see if the modified PC drive is the culprit this way. No need to do any other guesswork before ruling this out.

I'm loathe to do so as my external drives aren't suitable - a pc drive with adapter board is usually the go in the generic external drives and the other is an A1011. The Gotek is configured as it is.

I do believe the Alps could be at fault - maybe I'll replace it with another Chinon or Teac. Having 3 go and 2 psu's in a 12 month period makes it dubious.

[jbenam]

Originally Posted by Snoopy1234

My A1200 is reporting NDOS: or Unreadable: on DF1: with 2 of the external drives I have. I've checked the resistors and cap at the external port with a meter and they're ok. I've run Amiga Test Kit and Drive test and there seems to be signals but as there's no guide on how to read the results IDK.
DF0: is a modified ALPS drive and working normally. When comparing DF0: and DF!: in ATK and DT the results seem to be in opposite directions.

This happens with some drives - most mods out there assume that they’re going to be used as a single drive and as such this issue won’t show up.

I had to mod something like 8 drives until I found one that played ball with the second drive in my A4000 - AFAIR it had something to do with a properly clean SEL signal.

[Snoopy1234]

Originally Posted by jbenam

This happens with some drives - most mods out there assume that they’re going to be used as a single drive and as such this issue won’t show up.

I had to mod something like 8 drives until I found one that played ball with the second drive in my A4000 - AFAIR it had something to do with a properly clean SEL signal.

Ok I'll ask the seller of the Alps drive as he's the modder. Thanks.

[Snoopy1234]

Installed a refurbished Teac 235F as DF0: and DF1: is working fine so it was the modded drive causing the issue.