Atari SF314 to 'SF551' floppy drive conversion

Converting a pair of Atari ST SF314 floppy drives for use with the 8-bit Atari was fraught with difficulties.
Thanks to AtariAge member Manterola, here's a detailed explanation of the issue regarding the MCU jumper:
'[The] 8040 does not include internal memory, so a ROM (or eprom) is always needed. 8050 is just like the 8040 except that includes internal memory for the firmware, but also can work with external memory (like an 8040). The 8050 you used in the video is a generic one which does not include the firmware for the Atari drive and need external ROM for firmware. Therefore, you need to use the 8050 in "8040 mode", so you put the jumper in 8040. So it is not that the labels for the two positions are inverted. You'd still need to put the jumper in 8040 position when using a 8040 processor.'
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00:00 Intro
01:15 Sponsor message
01:48 Overview of the SF314 and 'SF551' boards
05:59 Parts required from the original board
13:02 Finishing assembly of the new logic board
19:06 Sourcing parts and working around board errors
22:32 Making a power supply
23:36 Preparing the operating system EPROM
25:32 Final checks
27:43 First test of the new drive
30:38 Diagnosing issues
33:40 Testing with the oscilloscope
38:05 Some signs of life
39:40 Autopsy
41:50 More problems
47:31 Yet further problems
49:44 Even more problems
50:46 All is revealed
54:52 The finished product and conclusion
Soldering and test equipment:
● Hakko FX-951 T12 soldering station: uk.farnell.com/hakko/fx951-64...
● Best BST-863 hot air rework station: www.banggood.com/BEST-BST-863...
● Anesty (Duratool) ZD-915 thru-hole desoldering station: cpc.farnell.com/duratool/d006...
● Hanmatek DOS1102 dual-channel oscilloscope: www.amazon.co.uk/DOS1102-osci...
● Amtech NC-559 Tacky Flux: store.rossmanngroup.com/index...
● Goot Wick Desoldering Braid: store.rossmanngroup.com/index...
● Cynel Sn60Pb38Cu2 Tin/Lead Solder Wire: www.tme.eu/gb/details/lc60m2-...
● SysCheck v.2.2 by tf_hh: www.abbuc.de/component/jshoppi...
Equipment and software used for video production:
● Open Broadcaster Studio: obsproject.com/
● 2x Logitech Brio webcams: www.amazon.co.uk/Logitech-Gam...
● 135W Photography Studio Softbox Light: www.ebay.co.uk/itm/135W-Photo...
● Final Cut Pro
● Apple Motion
● macOS Ventura running on a Dell 5060
#atari
#SF551