Floppy write protected (when its not) fix.

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exxos
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Floppy write protected (when its not) fix.

Post by exxos »

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This is a shortened version of this thread..https://www.exxosforum.co.uk/forum/viewt ... =23&t=1410

The issue was with a STE machine, which was continuously or intermittently reporting the floppy was write protected when it was not.

The assumptions are the drive has been tested and working fine in another machine. It is also assumed that the WP pin on the 1772 is always high (for write enabled operations).

The fix for this issue to solder a 10K bussed resistor array to the 1772 databus pins as illustrated below.

The white wire connects the common pin on the resistor array to 5V.

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Video below demonstrating one error without DMA pullups.


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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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terriblefire
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Re: Floppy write protected (when its not) fix.

Post by terriblefire »

Just made this mod to my STFM

Hasn’t helped my issue but was easy to do

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PhilC
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Re: Floppy write protected (when its not) fix.

Post by PhilC »

Just checking, as I dont have any 10k, do you think it will work with 4.7k?
If it ain't broke, test it to Destruction.
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Re: Floppy write protected (when its not) fix.

Post by exxos »

Forgottenmyname wrote: Sun Jan 20, 2019 1:09 pm Just checking, as I dont have any 10k, do you think it will work with 4.7k?
Assume would be ok..
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DoG
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Re: Floppy write protected (when its not) fix.

Post by DoG »

Did this on a STfm (070789-001 RevD) since I fitted 2.2 booster on it and having problem reading disks. Works perfectly now.

EDIT: v2.3 booster
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Re: Floppy write protected (when its not) fix.

Post by exxos »

DoG wrote: Sat Apr 06, 2019 2:28 pm Did this on a STfm (070789-001 RevD) since I fitted 2.2 booster on it and having problem reading disks. Works perfectly now.
Thanks for letting us know :thumbup:
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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tzok
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Re: Floppy write protected (when its not) fix.

Post by tzok »

This fix solved my issue with ACSI CF adapter in 1040 STfm. Before, it was writing complete garbage on the CF card, after applying this fix - works like a charm!
pixelk
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Re: Floppy write protected (when its not) fix.

Post by pixelk »

Thank you !

As I didn't have the right resistor network, I built my own.

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Seems to do the trick.
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Re: Floppy write protected (when its not) fix.

Post by exxos »

pixelk wrote: Fri Aug 13, 2021 10:28 am As I didn't have the right resistor network, I built my own.
Wow today's geek award goes to...
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FujiMan
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Re: Floppy write protected (when its not) fix.

Post by FujiMan »

I'd remove the chip, put a precision socket in and place the resistor array on the bottom of pcb. ;)
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