Monthly Archives: September 2015

E-MU Emulator II

E-MU Emulator II HxC Floppy Emulator

Ever since I got my EII I’ve been planning to add an HxC Floppy Emulator. These are some of the reasons:

  • One of the floppy drives doesn’t work and replacement drives are expensive
  • an SD card can hold a lot of floppy images
  • I don’t have a computer with a 5.25″ drive, so I have no way of transferring all the EII images I’ve got (could be solved if I get my Mac SE 30 and the serial thing working)

As the EII uses 5.25″ floppy drives, the connectors aren’t the same as for 3.5” drives. To solve this you basically have three alternatives:

  1. Create a new custom cable
  2. Create some kind of extension/adapter cable
  3. Modify the original cable

There’s a comprehensive manual from E M X P describing everything that you need to know about the HxC installation, including diagrams of the cables, whichever one you choose. Since I don’t like messing with the original one I chose to create one from scratch. I skipped the extension/adapter route since it would require a female 5.25″ connector, and I could as well create a whole new cable since I was messing with cables anyway. It’s also worth noticing that the cable is very long, almost a meter, which makes it nearly impossible to find a standard floppy cable and just add an extra 5.25″ male connector. In the picture below, taken from the manual, alternative 1 is the route I took. Alternative 2 shows the extension/adapter cable route.

Drawing of the 1) custom floppy cable that I make 2) The extension cable alternative. Screenshot from the E M X P manual (a must for everyone doing this conversion)
Drawing of the 1) custom floppy cable that I make 2) The extension cable alternative. Screenshot from the E M X P manual (a must for everyone doing this conversion)

Parts

  • About 1 m of 40-pin ribbon cable
  • Two standard 3.5″ floppy female connectors
  • One 5.25″ floppy female connector “34-way card edge connector IDC”
  • Lotharek REV F HxC drive (REV F is the 3.5″ floppy version). Buy it directly from Lotharek’s homepage. I should cost around €100, but I’ve seen “unofficial resellers” on eBay selling them for €150-200 – that’s a scam.
  • 5.25″ to 3.5″ adapter bracket, like this (I already had one from a computer chassis)
  • 4 pin Molex to floppy power adapter, like this (I had one lying around, probably included with a PSU)

Disassembly

First thing to do is to up open up the EII, which is a very simple process. Just a couple of standard Philips screws at the back and underneath. Then take the top of. Also locate the 4 screws that attaches the “floppy tower” to the chassis to remove it. 

At the middle of the main board, above middle C, a flat cable is folded, then going to the left, under the floppy tower and up to the drives. Remove this cable and use it as a model for the new cable.

Making the new cable

Prepare the flat cable by removing 6 of the wires to “convert” it from a 40 pin to a 34 pin flat cable. Then fold it at the exact same places and put the connectors at the same place, with one big difference – where the original cable has a 5.25″ for the upper drive, replace this with a 3.5″ connector. I used a vise to evenly squeeze the connectors to the cable. Make sure you orient the connectors the right way. Look for a little plastic piece between the 2nd and 3rd pins on the 5.25″ connector.

Swapping the faulty 5.25″ drive

The lower floppy drive didn’t want to load a disk that I know worked in the upper floppy drive.  Therefore I swapped them and carefully set their jumpers right. Now the lower one worked, but not the upper. Perfect, since my intention is to keep a working 5.25 floppy in the lower position and the floppy emulator in the upper position.

The faulty floppy drive with serial no 143922. Maybe it just needed cleaning, I don’t know –  I’ll keep it as a spare or something. It’s amazing the upper one works after 30 years…

5.25″ adapter and HxC metal work and jumper

I’ve used the HxC in lot’s of different samplers, and it has never properly aligned with the machine I’ve put it in. It always extends a couple of millimeters outside. So I decided to modify the HxC by drilling new holes in its metal chassis. For this I used 2.5 mm cobalt drill and used the adapter as a template. I chose this particular adapter since its pattern on the plastic matched the EII best.

Also set the jumper on the HxC to first position, as in the photos.

Floppy power adapter

For power to the HxC, a Molex to floppy power adapter was needed. Luckily I had a few of these lying around, probably included with some PC power supply, but never used. They can easily be found on eBay for a dollar or two. It’s simply connected to the Molex power connector that was previously connected to the now removed 5.25″ floppy drive.

Assembly

Simply reassemble the EII the other way around!

E-MU Emulator II

E-MU Emulator II key fix

Oddly enough, the E2-key on my EII didn’t trigger as it should, it was triggering very randomly. I suspected this was due to oxidation and opened up the EII.

Removal of a key is simple, but you have to be careful not to break the now 30 year old fragile plastic. You simply push the key downwards at the front, and then pull it backwards towards you.

I removed both the E2 key and its neighboring F2 key to get a better view. Underneath the key there’s a rubber mat which the key pushes on. Underneath the rubber mat is a small metallic surface that pushes another surface on the EII which results in a contact.

Lifting the rubber mat showed serious oxidation on the surface on the EII. I sprayed a cotton swab with electronics cleaner and cleaned the surface from oxidation. After that I put the keys back to test if the problem was solved, which it was!

When the keys were loose, I cleaned them from 30 years of dirt. I was tempted to remove all keys and clean them, but I thought it’s an unnecessary risk due to the keys being fragile.

E-MU Emulator II

E-MU Emulator II LCD screen change

One thing that sooner of later will die on your EII, if hasn’t already, is the backlight of the lcd display.  There are basically two things that can go wrong: The backlight itself or its transformer.

The backlight The original EII display don’t use leds for the backlight as modern displays do, but another kind of lamp. These can be replaced, but I’ve understood that it’s quite a lot of work, and it’ll definitively die on you again.

The transformer transforms 5V to a much higher that supplies the backlight with power. These kind of transformers often emit a high pitched frequency which can be quite annoying.  Since my transformer didn’t sound at all, I thoguht that this might be the faulty component, and not the backlight itself. The transformer used on the EII is the NEC NEL-D32-46.

The solution is to replace the whole lcd display with a newer one that has led-backlight and remove the transformer. On my EII I suspect someone has been doing some kind of operation on the display before, since the display wasn’t physically connected to the display.

Parts

EII OEM displays can be bought on eBay for a lot of money, and they will die sooner or later. There are also other modern “EII/SP1200 replacement lcd displays” available, but they are way overpriced.

Probably any standard modern 16×2 lcd display will work, but be careful when you look for one that it has the correct dimensions, 84×44 mm. Most 16×2 displays that you find are 80×36 mm, and they a) won’t fit in the standard mounts b) require a new flat cable to be soldered to the upper board. Take my advice and get one in the correct dimensions! There are some lcd displays avaible that don’t have backlight, you don’t want one of those. The lcds with backlight are usually 13.5 mm deep, the ones without 9mm.

I found a suitable lcd display manifactured by “Midas” on the UK eBay for around $30 including shipping to Sweden. They can be found much cheaper on Farnell and RS Components, but they require that you purchase stuff for a minimum amount.  I chose the model with blue background and white characters.  You’ll also need a new hex-inverter chip and two short wires for the power.

  • Midas MC21605A6WD-BNMLW 16×2 lcd display 84×44 mm with backlight, I bought it from here
  • Hex inverter Texas Instruments SN74LS04N (this was strangely enough in a zipper bag included with my EII when I bought it…)
  • A pair of 5 inch red and black wires

Replacing the display

Start by opening the EII and remove the upper board that the display is mounted on. More details on that in the E-MU Emulator II slider pot A replacement post.

First thing was to remove the transformer. I cut the melt glue and then used a solder sucker and some heat to remove it. I then soldered the red and black wire to get 5V and ground from the same place as the transformer did.

Next thing, and probably the most time consuming one, was to desolder the 14 pin flat cable from the old display. First I removed the four nuts so that the display was loose from the board. I then had to use plenty of heat and soldering wick. Because of the heat, the insulation on the flat cable took a hit and split itself, but that was actually not a problem, I see no risk in short circuits.

Next step was to solder the 5V and ground wires to the new display, 5V goes to hole 15 and ground to hole 16. The flat cable’s 14 pins goes to hole 1-14. I then reattached it with the nuts and nylon spacers to the board, it was 100% perfect fit!

Just for fun,  I booted the EII to see if my desoldering action had caused any damaged, but it didn’t! I did see the garbled text in the new lcd that I’ve read about in forums when you don’t have the correct hex inverter.

I turned the EII off and located IC25 on the right lower board, it’s near where the floppy cable connects. Make sure you work the right board and not the left, because there’s an IC25 on the left as well with the same physical dimensions! I removed the original RCA H 506 and replaced it with the SN74LS04N and booted. It worked, and it looked great!

Conclusion

I really recommend doing this switch, the display is very easy to read and also has a good display angle. The hardest part is desoldering the flat cable, other than that the swap is straight forward. Make sure you get a display in the correct dimensions as well, 84×44 mm, and double check that it features backlight.

E-MU Emulator II

E-MU Emulator II slider pot A replacement

Sooner or later one of the slider pots will fail on the Emulator. This has happened to the ‘A’ slider on my copy. The fault was that it simply didn’t work, no values were changed when sliding it. When I bought the EII, this slider was also missing a cap, so it wouldn’t surprise me if someone had done something to it before.

Parts

Replacement sliders can be bought on eBay for $15 + shipping or much cheaper somewhere else. I bought the exact same slider pot and capacitor at my local store, Electrokit, and it set me back $4 in total.

These are the parts that I got:

  • Slider pot 60mm 10k lin 40920001

  • Ceramic 100nF %0v Y5V axial capacitor 41003074

A few months ago I also bought a new slider cap on eBay for $5 + $2 shipping, it could probably be found somewhere else much cheaper.

It’s important to make sure that the slider has the correct form factor, in this case the “arm” that the knob will sit at was 5mm too short. On the other hand, the original sliders are mounted with 5mm nylon washers between the board and the slider. By skipping the washers, the new slider arm got the exact same height as the original ones. I stupidly forgot to photograph it…

Worth mentioning is that the four pins on the slider were positioned differently than on the original. They did have similar markings though: 1, 2, 2, 3.

Replacing the slider

The replacement process itself is very straight forward. Start by opening the EII and find the upper left board. Disconnect all cables that goes to it, and on the front remove the four slider caps and the volume knob. Finally unscrew six Philips screws and the board is loose.

The slider is then screwed to the board with two smaller Philips screws. I started by desoldering the wires though, before unscrewing the slider. I opened the old slider and it was obviously physically damaged, no wonder it didn’t work.

Then I screwed the new slider to the board without the vinyl washers in between, and soldered the wires and capacitor to the corresponding pin numbers. Luckily the wires were long enough to reach the pins even though the pins were physically in different positions.

Conclusion

I’d say the operation is very easy to do and that the A slider really is something you can’t live without unless you can settle for presets. The A slider is used for fun stuff like cutoff, start- and loop points etc.