Resurrecting a SF314

Update your old 720k to a 1.44 drive etc.
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jwd
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Resurrecting a SF314

Post by jwd »

Done the usual, cleaned heads, greased mechanisms etc. all good but very odd behaviour.

It will work 100% if using disks it has formatted itself. Those disks can't be read in any other floppy drive though and vice versa.

So its like is only want to play with its own creations!

Any ideas to get it to play with other disks have tried it on 2 different Mega ST's, same result.

Voltages to drive are 12.11V and 4.67V, could the 4.67V be the problem?

Any ideas appreciated.
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exxos
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Re: Resurrecting a SF314

Post by exxos »

I have seen that problem many times. I think the bottom line is that heads are likely out of alignment on the drive. I don't think this is really fixable though unfortunately.

I kind of got tired of those problems. So these days I use a MPF920 on my PC and ST to ensure things actually work.
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DoG
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Re: Resurrecting a SF314

Post by DoG »

4.67V is a bit low.
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Re: Resurrecting a SF314

Post by jwd »

I was hoping it wouldn't be alignment but first i will give it the proper 5V and see (currently it is still using the original PSU).

I think gadgetuk has done a vid on alignment but don't know how involved it is. . . . yet

I love the look of the external Atari branded drives so I suppose if i do replace the mechanism is the front facia re-usable on other drives so i can keep the aesthetics?
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Re: Resurrecting a SF314

Post by stephen_usher »

Given the (at least three) different versions of the SF314 it's hard to tell what the problem is, but the symptoms say head alignment and possibly the head is starting to fall off due to the glue failing. This is common with the Chinon drives. The top head just falls off.

Does it create single-sided disks which others can read?
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jwd
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Re: Resurrecting a SF314

Post by jwd »

The single-side creation comment gave me an idea, i managed to dig out an old magazine cover disk that had the side a and side b folder format to cater for the single sided drives.

Low and behold it was the top head causing the issue, everything on side a could be read, nothing on side b. It is an espson smd-140, managed to find some spec pdfs but not much help tbh

Watched this vid of gadgetuk -



Gave me some great ideas, still using the original PSU as stated previously when it got to a seek moment and couldn't read i gently pushed the head towards the centre of the disk and as long as i applied some pressure it would read ok, so first i tried the stepper motor adjustment (i thought) from the second half of the video (green circle below) :

epson smd-140.png
epson smd-140.png (882.02 KiB) Viewed 4982 times

but after about 2 hours adjusting the metal frame in the smallest increments i could, in the end it seemed just the limiter adjuster for the travel limits of the head, is that right? Where is the stepper adjustment on these drives?

anyways another 2 hours later of adjusting the top head back and forth, side to side, with the red circled screws trying to get it to read the side b i would finally get it reading it, yay i thought. No, tried a disk formatted in my other drive wouldn't read jack. :shock:

So seemingly like forever i adjusted all over again and again until i finally had it reading on all the side a/b disks i have and some disks shared between my ST's, not 100% but during the constant testing and trying on various drives I realised my other drives might be a bit finnicky too :dizzy: .

I currently having it working fairly well. Afraid to touch it again as to have it reading nothing . . . .
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Re: Resurrecting a SF314

Post by jwd »

Fast forward a month I have my diagnostic cartridge (for alignment menu where i can select a track and it stays locked), my oscilloscope at the ready with the drive test points identified and after watching every youtube video there is on the subject I am ready to have a crack of getting it near perfect.

Before I start I thought i would check again how the SF314 behaves and if there is any general failure on certain disks which includes coverdisks with side a/b format and floppies formatted on other drives, mainly to remind me of the specific issues again - all now seem to work.

Ok! lets try writing/formatting on SF314 and see if any other drives can read them (was a big no no a month ago) - now other drives are reading the SF314 floppies, WTF! I had one small error on a disk but attributed this to a dodgy floppy disk. In the preceding month I had done nothing except let it be naked and gather dust (not the best analogy but it was covered to prevent exactly that). Magic yeh!

So with a proper WTF face on i'm wondering what has changed, weather, planet alignment etc.

Then i noticed as I was about to use my diagnostic cartridge for this I had unplugged my Spectre GCR and so nothing was in the cartridge slot of my Mega4, a month previous all the testing was done on the Mega4 with the Spectre GCR cartridge plugged in, when testing with other ST's I was using the same floppies that had been prepared/written while the SF314 was connected to the Mega4.

The Mega4 PSU has been re-capped and larger caps on the motherboard replaced too so I doubt this is a power issue but could this be related to @exxos excellent posts on mandatory fixes (which will be next on my todo list) :

https://www.exxosforum.co.uk/forum/viewt ... =17&t=1417
or
https://www.exxosforum.co.uk/forum/viewt ... =17&t=1395

Would something plugged into cartridge port affect floppy drives, more the external drive in this case?

Does anyone have any idea why a plugged in cartridge would cause so much pain here . . .
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Re: Resurrecting a SF314

Post by exxos »

jwd wrote: Thu Jun 09, 2022 4:01 pm Would something plugged into cartridge port affect floppy drives, more the external drive in this case?

Does anyone have any idea why a plugged in cartridge would cause so much pain here . . .
Bus loading. It's a classic sign of why the bus resistors need to be changed. Plugging in a cartridge can cause a machine to magically spring to life, or prevent it from even booting, plus everything in between.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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jwd
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Re: Resurrecting a SF314

Post by jwd »

exxos wrote: Thu Jun 09, 2022 4:19 pm
jwd wrote: Thu Jun 09, 2022 4:01 pm Would something plugged into cartridge port affect floppy drives, more the external drive in this case?

Does anyone have any idea why a plugged in cartridge would cause so much pain here . . .
Bus loading. It's a classic sign of why the bus resistors need to be changed. Plugging in a cartridge can cause a machine to magically spring to life, or prevent it from even booting, plus everything in between.
Thanks @exxos for confirming that, are you specifically referring to this thread when you mention bus resistors to be changed:

https://www.exxosforum.co.uk/forum/viewt ... 235#p27504

Is this in conjunction with the other mandatory changes I have mentioned above or instead of?

thanks again.
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Re: Resurrecting a SF314

Post by exxos »

jwd wrote: Thu Jun 09, 2022 5:03 pm Is this in conjunction with the other mandatory changes I have mentioned above or instead of?
All the fixes need doing.
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https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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