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General Category => NC100, NC200, PCW, PDA600 - the rest of the Family! => Topic started by: Starglider on 05:10, 22 September 15

Title: How to fix PCW drive "missing address mark"?
Post by: Starglider on 05:10, 22 September 15
I thought it would be a good idea to move the discussion away from the "Wanted" board and into a more focussed area to hopefully pick up some PCW experts.

Please take a look at this thread about my EME-232 drive that I have installed as "Drive B" in a PCW 8256: http://www.cpcwiki.eu/forum/classifieds/wanted-amstrad-3-inch-floppy-disk-drive-compatible-with-pcw8256-pcw8512/msg109611/#msg109611

Quote
I ... reversed wires 4 and 6 [to allow the drive to be "B:"] as per the article ... Photo: https://goo.gl/b5k8wl (https://goo.gl/b5k8wl)

Good news! Now Drive A boots and Drive B appears to the system!

Bad news! I'm getting an error on any disk inserted into Drive B, even disks that boot fine in Drive A. The disk "groans" back and forth twice then says:

B: track 0, sector 0 missing address mark

It has been suggested that it could be a head alignment, or calibration, or head cleaning issue.

- I have cleaned the heads
- Calibration looks very complex with CAD charts etc. when we're not sure if that's it
- I am buying some blank 3" disks from @pacomix (http://www.cpcwiki.eu/forum/index.php?action=profile;u=855) to test writing with

Could there be a simpler fix? Is it an issue with my swapping the wires perhaps? Here's where I'm up to:

Quote
Does anyone know of a 'fudge' to mess around with alignment temporarily? Truth be told I only need access to the DD drive once, to read an old childhood disk. Once I've read it and seen the contents I'll be satisfied  ;D

I want to do that on my own, so any tips for what to either push on or prod or screw or unscrew, that aren't as complex as the instructions at the above referenced site (creating CAD charts etc.) would be greatly appreciated. As would any disk alignment software or other pointers to what could be wrong here.
Title: Re: How to fix PCW drive "missing address mark"?
Post by: Bryce on 11:17, 22 September 15
If it really is just a once off thing, you could try blindly adjusting the RPMs. Try reading the disk. Then turn the adjust screw about 5% clockwise and try reading again. If it doesn't work turn the screw 10% anti-clockwise and try reading the disk again.

Blind head alignment is more or less impossible, so I wouldn't even try that.

Bryce.
Title: Re: How to fix PCW drive "missing address mark"?
Post by: Starglider on 16:04, 22 September 15
Thanks. Could you advise location of screw?

Thanks!

"Recordar es vivir"

Title: Re: How to fix PCW drive "missing address mark"?
Post by: Bryce on 16:11, 22 September 15
Not sure about the EME-232, either it's directly on the motor or on the PCB. Maybe you can compare yours with the pictures here: Amstrad FDD part - CPCWiki (http://www.cpcwiki.eu/index.php/Amstrad_FDD_part)  Or post some pictures of the motor and entire PCB from yours.

Bryce.
Title: Re: How to fix PCW drive "missing address mark"?
Post by: Starglider on 03:40, 23 September 15
I'll give it a whir!

Thanks!

"Recordar es vivir"

Title: Re: How to fix PCW drive "missing address mark"?
Post by: gerald on 09:55, 23 September 15
Not sure about the EME-232, either it's directly on the motor or on the PCB. Maybe you can compare yours with the pictures here: Amstrad FDD part - CPCWiki (http://www.cpcwiki.eu/index.php/Amstrad_FDD_part)  Or post some pictures of the motor and entire PCB from yours.

Bryce.
Looking at that one (http://www.ebay.co.uk/itm/271993689113) on ebay, the EME-232 is the double density / dual sided version of the EME-156.
Speed adjustment is on motor, but it seem that the potentiometer is mounted upside down (white rubber hole), and can be damaged if forced or if the screwdriver is too wide.