PC Archeology: The plasma screen is probably the best thing about Schneider PC 7640 

Hi Adrian, I'm not a power supply engineer, per se, but an electronics engineer with 80's era switch mode power supply design experience. There are two potential issues I can think of when running switching supplies below their rated voltage. One is that, switch-mode supplies are "constant power" devices, so they will draw more current as input voltage is lowered. That could overheat input circuit components or blow a fuse, if running well below rating. The second issue is that these supplies typically regulate output voltage by adjusting pulse width to a step-down transformer. Lower input voltage causes the pulse-width to increase, thus increasing the peak magnetic field strength in the transformer core. There is a maximum pulse-width, which will cause the transformer core to saturate. Saturation causes the primary's impedance to drop rapidly (essentially, becoming a wire), which would then drastically increases current flow. If a current limiting measure is not implemented, this could damage components. This saturation effect would also happen if supply output is shorted. I bet that any PC power supply would have active over-current / under-voltage protection, beyond just a fuse, but can't guarantee. Keep up the amazing work!

Hi Adrian, Berend here. Thanks for another great episode and happy we could contribute by donating this machine. Don’t feel bad about mispronouncing my name. Almost every American I met didn’t get it right the first time, so I am impressed you got it right at the end of the video.

'Velcro' is a portmanteau of two french words 'velours' (velvet) and 'crochet' (hook) named by the inventor.

1:02:06 "I don't think I'm gonna film that, because there's gonna be a lot of cursing..." Adrian, you are a gem! 😂

I used a Toshiba 5100 back in the early/mid 90’s. It was a 386 but still had the orange plasma display. I worked for the railways in Sydney Australia and we wanted a PC for field work but the government procurement regulations at the time banned the purchase of laptops. To get around this problem, we got the supplier to sell us two units with bundled hardware modules and they listed them as protocol analysers. They were very capable machines in their day and were used a great deal by me and my team into the 2000’s.

The floppy issue is probably due to the original using the READY signalling on Pin 34 rather than the IBM-PC DSKCHG signalling. READY will go low when a disk is in the drive so the system wouldn't be able to tell that the floppy is in the drive so never try to read with the PC drive in there.

The thing I hate even more than the complexity of working on laptops, is the amount of plastic clips and thin plastic brackets that are often used. Over time the plastic becomes quite brittle because of the heat and age. I always end up breaking something, then have additional work to fix that. Thank you so much for this video Adrian.

Hi Adrian, in The Netherlands we use the US International keyboard layout. There are keyboards with a Dutch layout, but we use it very rarely. I've seen it once in production 25 years ago.

Holding the disk platter in hand ... "Well that escalated quickly"

I love the Adrian's Digital Basement QC Sticker. It gives me more guarantee and security to trust that floppy drive than if I had bought it new.

I remember the Toshiba (T3100) plasmas being much brighter than any of the early LCDs that were available, and it was waaaaay waaaaay better to type on. If you were using it for business, the plasma screen offered a way to type a document or something in a hotel room that was quite a reasonable experience. I do think they have dimmed over time

Love seeing Dave's lovely multimeter. Forget the expensive Fluke, Dave's meters are amazing.

This is precisely why I appreciate the GRiDCASE 1500 series so damned much. They crammed top notch displays, into a portable form factor that could take a beating.

Most modern power supplies support multiple input voltages because they contain as first stage a power factor correction circuit that is implemented as a step-up converter and boosts the voltage to around 450 Volts internally regardless of the input voltage. Power factor correction is mandated by EU law for all consumer devices above 70 Wats. Since most consumer products are made to confirm to world-wide standards, they come with power factor correction and therefore support multiple input voltages as a freebee.

Honestly that masking tape has probably held up better than most electrical tape would. The soldering looked pretty decent.

Great video - it demonstrates that electronic repair on vintage equipment can sometimes be a challenge. I'm glad that plasma screens had a relatively short life-span.

I love the long videos. 💚

230V - 50Hz (used to be 220V too) also here in Greece single phase for homes but if you measure it you will see great fluctuasion from even under 190 to 250V which is really bad overall for electronics so a stabilizer is very useful especially under thunderstorms... We had a lot of Schneider PCs here and even if I respect Japan's products many times their companies design them in a really bad way for expandability-upgradeability and fill them with proprietary connectors and stuff which is really a shame and puts aside the great build quality of them. Great long video as always Adrian, keep up, JIm.

Us dutchies are used to using US International keyboard layouts. Usually using deadkeys to compose characters like é or ë etc. And we have a € symbol on the 5 key which can be typed with the "alt gr" (usually the right ALT) key. There is an actual Dutch keyboard layout which is also QWERTY but has the symbols moved around. I haven't seen those since typewriters and maybe old 8088 computers.

Couple of videos by Shelby over at Tech Tangents dive into floppy disk formats and how the media is laid out, which would explain why the 1.44 disks might not work in some of the 720 drives, which is partially due to how the signaling in them works I believe.

Excellent job as usual and very informative. TY Adrian for all that you do for us!

Hi from Germany :-) Love your videos. Everytime i'm very impressed from your work.

I know you said this was an unplanned deep repair… but this is the content I’ve been craving recently. I appreciate your commitment and followthrough. Thanks for all you do! I truly appreciate your information dense videos and soothing voice. I’ll totally be patronizing soon.

On the Yamaha chip, the Japanese text credits ASCII Corp. It's a different chip/part no, but the same credit is also found on the MSX custom chip that integrated a lot of the chipset logic together into one chip.

The Voltage in Europe wasn't changed, it was just the spec that changed to incorporate the Brits with their 240-240VAC. In my house the Voltage remains at 220VAC or 380V for 3 Phase. Yes, I measured it with my Multimeter.

I am a new viewer to you're channel and I do like your enthusiastic, yet realistic approach to troubleshooting. It's funny because there is this kind of an "Art vs Commerce" paradox that you run into when taking on these projects, on one hand, you want to be detailed and concise on the other hand it has to be done within a time limit and one doesn't want to bore the viewer getting into theory, or spending too much time on uneventful yet necessary tasks. I will be tuning in from now on, Thanks.

wow for a quick description of how power moves through the power supply, that was kind of awesome!

I would wager in that generation of system/computer it might have required that before the computer was turned off to actually PARK the hard drive.

My Dad had a Toshiba model similar to this one from around the same time period. It was a 286-10 I believe with the same CGA plasma screen, a 720K floppy drive, a 20MB RLL hard drive that was loud as all get out and the thing practically made the lights dim when you turned it on. He bought it second hand to use with his business, but didn't end up doing a lot with it. I used it with WordPerfect 5.1 for school stuff and also played a bunch of old Sierra games on it. I think I beat Space Quest 1 probably 15 times on it, to the point where if speedrunning was a thing then, I'd probably have been competitive with that game. The clarity on the screen was actually quite good, though it was only a few years old at the time so it was still in good shape and came with the bonus of being able to heat your entire room all by itself. I'd really love to find one of that Toshiba machine for nostalgia's sake, but finding one with a good screen is next to impossible and it would cost an absolute fortune to ship.

Picked up one of these Gas Plasma era portable beats this week - an STM5500. Can't wait to tear into it and get it all cleaned up. A portable with Canadian roots in my collection.

This "Laptop" is not from Germany, it's from Netherlands so keyboard layout is almost the same as UK layout

Brilliant video as always! I have an old Roland workstation sampler that has a 720k drive. Over the years I’ve found some 1.44mb disks work when formatted with the tape over the whole and some don’t for some reason

The problem with DD formatted HD disks is that the retained flux in the platter is lower than with true DD disks. That`s because the size of the nickel-iron oxide grains on the platter is greater in DD disks. So some of the DD reading heads don't get excited enough to read the data successfully. I had that problem often with my Atari ST machines and i think the cheaper drives have that problem. It can help to write the data with a DD floppy, because some are using higher magnetic flux than HD drives to write the data.

Well hello Adrian. I suppose the extra FDD power cable mod was intended to be used with a replacement FDD to bring both 5V and 12V. The 720k might work fine with just the 5V whilst the other not so much

Very early SMPSU did have a possibility of damage under low voltages due to instability of the switching. Also at under voltage events it may trigger restart of the power supply. Usually the power supply for the power supply control circuit usually fails to start so not to cause damage on under voltage but once running low voltage can cause more damage due to higher loading. As far as I have found the units controlled with an SMPSU dedicated controller IC have no damage just the ones using discrete parts. Most modern PSU work from 100V(Japan) to 240V(UK now dropping to 230v) to keep life easy. I have popped a SMPSU drive transistor again using a Variac so now have power limiting on it & check the circuit diagram first.

Amazingly sharp transitions between the lit/unlit phases at around 10:00 when you're showing the screen rolling slowly; a gas plasma display like this could in theory be refreshed extremely quickly without resulting in any smearing or ghosting, based on that.

In the 1990s the voltage in continental Europe was increased from 220V to 230V. England uses 240V, but at least 230V. A power supply for 220V also works well on 230V. In the US, 230V is also possible. Houses are often supplied with 115V split phase. That means between one phase and neutral it is 115V, between two phases it is 230V. 200-230V is used in the US for the cooktop and tumble dryer.

Poor Berend is "Bernard" now. =( Regarding key layout, the Netherlands uses QWERTY. They most use US layout for cost reasons though there is a Dutch keyboard with only a few tiny differences on punctuation keys.

From my experience, I can't see how running the computer at the lower voltage would damage it. However, I can't imagine it working on the lower voltage. I have a lot of old solid state and tube type equipment, and when they haven't operated for some time, I use a variac, and run them starting at lower voltage, so that the electrolytic caps, have a chance to re-form. That way, I am able to get the machine operating, and then check to see if I have a potential problem, by looking for hot electrolytic caps. I have been doing that for over 30 years, and never experienced a problem. I enjoy your videos, they are highly instructive.

Lots of great linguistic gems in this episode. I wonder if the plasma controls are behind the bezel or trim pots on the board? My dad had an Osborne portable computer. That thing was a beast.

What a great documentation of the thing online.

I saw one of these when i was young, playing a battleship demo in Grace Brothers - a high end retailer in NSW and the display amazed me. Good to see one working again. As for my own retro laptop, i have a Powerbook 100 that was working in the early 2000s that I want to restore an eventually take on the internet.

Adrian did *a lot* of work in this video, and it's unfortunate that any data couldn't be extracted from that MFM HDD, but it was *still* fascinating to see into the nuts and bolts of an example of the "laptop" technology that existed almost 40 years ago.

Quote of the week: "There's not much to report. It's beige." - I was howling with laughter

Hello Adrian, this videos comes very andy for me, I'm in the process of restoring an older Schneider, Euro PC to be precise. The battery situation, I don´t know what value to se for the Diode, I have this around Schottky 40V 1A - 1N5819, do they serve the purpose? Thanks.

Wow. Nice. I worked there . Grèetings from Bavaria Germany

The reason the 1.44MB fdd did not work in this machine is that it requires 12V as well as 5V, and that is prolly why that extra fdd power connector was bodged in.

I remember 400K macs (and maybe 800k?) had issues with taped over disks because the disk detect switch was in the exact spot that the high density hole was. So when you put a disk in, the computer wouldn't think a disk had been inserted and therefore would not eject it without using a papercliip.

I think the clock chip is the OKI 16 pin DIP between the 32kHz crystal and the camera. The NiCds running those chips were almost always charged through a small signal diode and a resistor (often 470Ω) to +5 which is easy to Ohm out from the battery plus lead. I wouldn't be surprised if that resistor was R62 and the diode was D1, with D2 providing Vcc to the OKI clock chip during normal operation.. Just clip the resistor and/or diode out and you're safe to use a CR2032 without any protection diode which will reduce the useable life of the battery by quite a bit due to Vf.

Adrian, Have you ever thought of picking up a set of those soldering tweezers? It’s a dedicated iron, that has two heated tweezer arms. That you can use for taking caps, resistors, fuses, and other components off, and on. I found they work for when you’re dealing with small components and need to use tweezers to hold things still, an iron, and maybe some solder braid/wick all at the same time and you King have two hands. Lmk your thoughts. Edit: To save you from some searching. Here’s a pair on eBay. Amazon also has some cheaper “smaller” ones that may work better for the small components. But for older electronics such as the ones you work on, these larger ones should do fine as everything back then was bigger. lol. 110V SMT IC SMD Hot Tweezers & Soldering Iron Desoldering ESD soldering station

i had a Schneider/Amstrad PC1512 in the past. seeing an 286 laptop from them seems like a novelty to me. But i like the idea of restoring it!

A quick note on that FDD with the resistor for the drive select; that's a Zero-Ohm link so you can replace it with just a solder bridge blob, though you are forgiven knowing that you sometimes struggle with seeing small things like that, even I'm starting to have trouble reading resistor numbers like that given I'm approaching 40 and the eyes are getting worse for close-up stuff... :)

Tripped out video, Adrian. Thanks! Do you ever watch Sorin (Electronics Repair School)? He's a great tech, too.

Wizardry Proving Grounds of the Mad Overlord would look awesome on that red plasma display.

Hi Adrian. I wonder if there’s a newer (and smaller) version of the MFM emulator nowadays? One that has one or 2 GALs (or an FPGA) instead of the glue logic chips on the one you have. Then, maybe it would fit. 😊

Working as a 'counter person' at a classic electronics store in the mid-80's, YUASA was our main (sealed, lead acid) battery vendor. At first I thought that name sounded so familiar and then like a jealous GF, it finally hit me. I use to sell them. Unfamiliar with the Nickle Cadmium ones though.. Thanks for the flash back

That's a beautiful machine

When Adrian goes gun shopping he prefers the Phased plasma rifle in a 40 watt range.

My 1st Computer was a Schneider CPC 6128. Schneider used to build/distribute Amstrad Computers for German speaking Countries. At some point Amstrad/Schneider parted and Schneider made some of their own PC Creations. My 2nd Computer was a Schneider EuroPC. I could bite my a$$ for not keeping it 😢 This 7640 one was still licensed from another Manufacturer before Schneider came out with their own "Euro PC / AT" Series, which then also had non-US Style Keyboards. FunFact: The EuroPC was CGA and HercMono, depending on Bios Setup+Monitor.

There´s something I wanted to ask you Adrian for some time, other than nostalgia and "honey!!!...Need a rag down here!!!!...throw me something!!", that 20yr old green-blue towel that you use, I used many of them when fixing things, speccially to re asseble already clean parts and is the best surface to work on, inspite the fact that they loose threads like a sheepdog. I love them!. So, is like that for you too

I know this is not much related, but I want to share this so everyone can have a laugh... :P For the longest time (YEARS), I wondered why the hell floppy disks had CH written on them.

This was cool. A classic Adrian long video!

There are ML2032 batteries that are Li-ion, but have the form-factor ef CR2032. ML2032 of course have the nominal Li-ion voltages, meaning 3.6V or 3.7V nominally instead of 3.0V, and 4.2V fully charged. They can be used in place of your 3.6V NiCd however. I use them all the time both for projects like these as well as CR2032-powered devices such as candlelights that don't care so much. Even my 300€ Tesla key fob seemed to work initially with it, but then fried. The Sega Dreamcast used these originally, but I don't know of any other product that did so, and even there they were welded with tabs that were soldered, so I replaced that with a CR2032 holder on my Dreamcast..

I own a Toshiba T5200/100 with a working plasma display, and it's my favorite weird DOS gaming platform. It's not blazing fast, but it does have a 33 MHz 386DX with the 387 math coprocessor installed, which is enough for Wolf3D. It's also got a 100MB IDE hard drive, and 4 MB of RAM that can be set in BIOS to be either extended or expanded RAM. The panel is 640x480, and it supports all the CGA/EGA/VGA resolutions & color depths. (emulated through monochrome, obviously.) It also has a VGA out that mirrors the onboard panel. It doesn't have PS/2 ports; it's a few years too old for that. But it does have a serial port for a mouse, and some kind of proprietary port for an external keyboard. But what's best about it is that it has two full-size ISA slots; one 8-bit and one 16-bit. I put a Sound Blaster 16 in one and an XTIDE in the other, which really works out well. It's a fun little oddball of a machine.

A hard disk that needs a pull starter? PS, several shows ago you mentioned you did not have a set of Mac System 7.1 disks. I discovered I do have them. Do you still need a copy of them? They are HD so would take some fussing to get them on 800k disks. But disk images can install from an external hard disk.

My stepfather was working in Germany for a year around 1987-88. When he came back to my mum in the UK he came back with a Schneider desktop with a CRT. I assume it was from this generation. He had DOS and x86 CP/M which he preferred.

Reminds me of reviving some much later Compaq SLT models from late 1988 that I recovered in like 98-99. I wish I only had the means back then to transport and store some of the pallets of vintage gems that were just getting tossed in dumpsters year after year.

Hi Adrian, The floppy drive that came with the computer used 5 volt only it's spindle and head stepper are rated for a 5 volt operation that is probably that other berg connector was there someone used a 1.44 in there with it for a while.

I think my dad bought something like this back in the 90'es. It was a second hand purchase that he never got much use out of. I remember it was a pretty heavy laptop (too big and heavy for the lap) and it had a red screen. Unfortunately it was very dim even back then, so it was a strain for the eyes to use it in bright daylight.

That's a freaking gorgeous machine. I'm looking into acquiring a Tandy 1400HD or an IBM PC Convertible.

Larger homes in sweden have 3 phase 400V 16A connections for stoves, washingmachines and larger electric tools. This is split in to 240V at 16A, 10A or 6A lines for lighting and small appliances.

Would a 1.44 drive maybe work if you change it to 1.44 in the setup? I think it was at 720 when you tried it at first.

Switching PSUs are usually quite tolerant of moderately lower voltages and most modern designs are like 90-250V universal input, but this is old stuff and the label was explicitly 220V, so I would not risk using anything lower than 200 V.

Do you have a link to the rom dumper that you used? I've searching for a good one.

"Schneider Rundfunkwerke" (Rundfunkwerke: Broadcast Factories) - That is a pretty old name Schneider used back in the 80ties. Later after 1988, the Division of Schneider (that originaly build radios and radio cabinets) was renamed "Scheider Euro PC"

Yes, feeding a 220V ONLY PSU with only 110V can damage it. Because half the voltage -> Double the current. And the components inside might not be made for that and blow up. For older PSU like this uses, they use a special pump circuit for boosting the Voltage called a Voltage doubler. For that you need to replace the diodes with stronger ones or the Bridge Rectifier, possibly replac the Caps with more capacitance ones. Active PFC ones in modern PSU have a boost stage anyway, those can't be converted and would blow up. That is the case for most modern Consoles for example XBOX One, PS3-5 and so on. Because its just a buck or two cheaper to not make them universal voltage.

Wow! The moulding looks almost exactly like a Toshiba T3100. But the Toshiba gas plasma laptops were charcoal gray. I recently sold one of these to another collector on Facebook along with a T3100SX. Im guessing like many companies were reselling different models of Toshiba laptops.

Do Ni-Cad batteries tend to leak more when they are fully discharged? If the computer was used often I would assume there is less likelihood of leakage.

I used a Compaq luggable with a similar orange plasma screen back in the day. To my memory that panel was indeed slightly brighter and perhaps with a somewhat sharper rendering. That Schneider is a nice relic - it would be quite acceptable with a SSD in it (assuming that's possible with some magic adapters) running Turbo Pascal and such ;-)

you mentioned filter caps? i didnt get a good look at the iec input but they could be in there. unless it was another type of filter you meant.

I had a similar vintage orange plasma screened laptop in the early 90s. It was a hand me down. I don't remember the screen being particularly dim. In fact I remember it being pretty vibrant. I did a lot of homework on that machine using a word processor named KenWriter and printing to an old Epson RX-80 I was still rocking from my C64. I also did my programming work on there for tech college. I remember writing Cobol code and jcl to get it running when I took it to the mainframe. I even gamed on it and dialed in to BBS' in the evening. Neat machines, I kind of wish I still had it.

hello! Where do you find the rom dumper program! thanks!

Hi Adrian! It looks like the laptop has straight floppy cable. Your 1.44Mb floppy drive is most likely expecting the cable to have a twist. Like you self said on the video - the twist takes care of the drive select. You might get the 1.44 Mb drive to work if you try it with twisted floppy cable. if your 1.44Mb drive mechanics spindle did spin, but led did not get on, you might also try a poor mans job: the DS0 signal comes in wire 14. Cut wire 14 and connect it to gnd on the drive mechanics end (say pin 13 for example). Leave the laptop wire no 14 unconnected. This will result the drive mechanics to be constantly selected. The led is constantly on, but the drive should work normally. Not elegant, but practical to at least test if it works.

Adrian, did you use a 1.44 floppy to boot with the 1.44 drive? The BIOS defaults to 720 when it's reset to default, so that's probably why the 1.44 drive didn't work. It's been really long since I did anything with floppies but pretty sure a 1.44 drive configured as 720 in BIOS can't boot from a 1.44 floppy.

I recognize the packing material. There are two chemicals in separate containers, and it's similar to the foam insulation stuff you buy to seal doors and windows, but it's intended for packing. I worked at a computer shop for a couple of weeks while taking a computer class in A+/CCNA, and they had these two large containers connected to an air compressor, and it would mix the two chemicals and spit out that foam which would then conform to whatever object you were packing (without damaging the packed material at all).

Wonderful people like Peter and Berend in the world. Excellent.

I've got an old 286 laptop like that with a dead or stuck hard drive... it's in my "some day" pile because I dread taking it apart for exactly this reason!

1993-96 at university, I had a 2nd hand down IBM PS/2 P70 luggable (a gaming buddy worked at a big IT company and they were getting rid of them at the time, going to actual laptops so I paid about £300 for it which as a mature student was just about affordable). It was quite the beast, Gas plasma screen, 386dx cpu, 8mb ram, 120mb hard disk, Microchannel Sound Blaster, my mate made sure it got specced out to the max from his companies parts bin. Doing essays and coursework however, it was a sweet machine indeed, playing Doom however... that was a challenge (is that water or lava I need to run across? they looked the same, only one way to find out!). Sold it on when I graduated to another student who got a few more years very good use out of it.

For the disks, it depends what drive you use to format it: if you format a disk with 1.44 drive using 720Ko format standard, you'll find 720Ko which won't read it. Same with HD/DD 5"1/4 drives.

Adrian, I don't know if this holds true, but on some sophisticated 1.44MB 3.5" drives, in addition to the micro switch to indicate support for 720KB or 1.44MB there may be an optical sensor. If that optical sensor sees light through transparent Scotch tape, it won't work in switching to 720KB mode.

When you started saying the company name Oki Data, I wondered why it sounded so familiar. I went looking and realized the printer I have my for my Commodore 64 is an Oki Data brand. 😄

About the power supply, just change the plug to use the 240 V receptacle you use for the air conditioner. Or add a 240 V receptacle, with all that electrical stuff you must have a 240 V circuit somewhere around the place.

I'm surprised someone hasn't made a RP2040 based MFM adaptor. I've used them to build my own C128 board entirely (basically an emulator to be fair, but different microcontrollers handle different category/sections of execution and communicate together and with other chips like memory, the entire reason I built it was to mess around with having a few working together). As slow as those drives were relatively speaking in reading/writing data, it shouldn't be out of the realm of possibilities for a bulk of basically everything to be handled by a pico/pico based microcontroller.

6:58 DeathDaptor™ Never leave home without one! 8:00 Hmm, it's some odd variant of a UK layout because the left shift is wide, rather than narrow and with the pipe/backslash key to the left of the Z. 49:30 That went from "hospital bed" to "morgue" really quick!

Most SMPSUs you encounter will either be forward or flyback topologies. Forward converters (usually found on higher-output supplies) will usually have two primary-side transistors and each output will have a double-diode feeding an inductor. Flyback converters (common on lower-output supplies) only have a single primary switching transistor and each secondary has a single diode (or paralleled diode) directly feeding a capacitor without an inductor. Forward converters cannot produce full output voltage on reduced input voltage but flybacks (like this one appears to be) can. The main consideration is that the current in the primary coil and transistor will be higher and this could lead to overheating under full load. It might also have reduced output capability TLDR: it will probably boot on 120v, at least without the extra load of hard drive. A quick test at 120v isn't going to hurt it but continued use might.

Great video

It seems that it would be possible to fix this plasma screen mentioned at the very beginning. If you're familiar with the "zebra strip" idea, there is something of this kind in a form of double-sided adhesive tape. You could try to detach signal ribbons from the screen and then reattach them using such tape. If it's the matter of connection, it should work.

There seems to be a few similar-but-different machines built by the same OEM out of Japan. I have another variant, the Ai-PC16 sold by Ai Electronics Corp. in Tokyo, but probably also manufactured by Oki. I believe it was an imported unit, originally sold in either Australia or New Zealand, because it has a factory-fitted 100-220V AC 50/60Hz power supply. The machine has a date code of "8901", presumably Week 1, 1989. The case and internal chassis is very similar, but the rear layout is inverted - the expansion slot and power connector is to the right of the IO ports. Mine also has the cutouts in the case on the opposite side from the Floppy Drive to install a second drive, but it has a 3.5" blanking plate installed with a 40MB NEC MFM drive fitted behind it. Mine also shipped with a 1.44MB floppy drive as standard. The bodged Floppy power is probably an aftermarket modification. Mine doesn't have a Berg connector coming from the power supply, instead the Floppy cable from the motherboard carries power, and two wires are broken off from the ribbon cable to a Berg connector. Only the 5v and GND wires are connected, no 12v. A couple of quirks I noticed with mine that may also apply to the Schneider - when the battery dies or the CMOS is reset via another means, the BIOS defaults to running the Floppy drive in 720k mode. If I boot from a 720k disk, reconfigure the BIOS and reboot the machine, I can then boot from a 1.44mb disk. If for any reason the CMOS becomes corrupted and the machine just hangs on boot, I've been able to skip the long wait by removing the battery and grounding out the positive terminal of the holder (with the machine unplugged), which seems to discharge whatever circuit is still somewhat powered and resets the CMOS back to defaults. Although most variants I've managed to track down seem to use the 1.29E version InterLINK Business Network Corp BIOS (I think I've seen one exception running 1.30), the SETUP utilities differ between models. The Ai / Rein compatible setup utility doesn't work on a Schneider and vice versa. Your video likely answered the question of why this would be the case - different versions or revisions of the motherboard. Overall these aren't particularly useful machines, but it's still one of my favourites. It serves mostly as a dumb terminal, connecting to bulletin boards and other services through a null modem cable to another machine running TCPSER, and the plasma display makes it look very cool while it's doing it.

I wonder if the 720K sense is an optical sense instead of a mechanical switch. The translucent tape could be allow enough light thru ??

My Tandy 1100FD always had problems with 1.44MB floppies formatted to 720K.