The Emulator I, released in 1981, was the first member of the famous E-MU Sampler family. It started with a price round about 10.000 $. Now ... after 35 years, these instruments are so rare that there is no big difference to todays value ... if they are in a good working condition.

As this unit came to me it was everything else than in a "good working condition". It was completly dead and after a first look at the Power Supply, my worst fears come true.

The +15V Rail was defective and provides unregulated +19V to all Boards. This normally cause damage to everything that is connected with the +15V Rail ... and that are mostly the analog components of the whole design. Before any repair could take place this issue must be solved.

A complete rework of the Power Supply was necessary. I changed all capacitors against new ones with lower ESR and extended temperature range. All Voltage Regulators are swapped and mounted with fresh heat-conducting paste. Don't forget the thin mica isolation-slices for the negative Voltage regulators. Two pictures show the Power supply board before and after restoration.

Now the repair process could start. After I checked all of the supply voltages I connected the Mainboard first. In each microprocessor system regardless of the CPU-Type, Data- and Adressbus must be work properly. Digital signals on each bus, on each line, must be in the appropriate range. At this unit I found a lot of unvalid signal levels on the adress- and databus. This issues must all be solved to bring him back to life.

In detail that means ... look at the schematics, identify each component that is connected to the faulty line and check if it is defective or not. Replace defective components and repeat this steps until the signal is valid. Do this for each line of the Adress-, Data-, and Controlbus.

I replaced a lot of defective standard IC's and 2 defective DMA Controllers until all busses are valid. Then I connected all other Boards and checked the integrity of the Power Supply Voltages and all Bus-Signals again. A lot of errors appeared with each board that I connected. Each of them must be searched and repaired before the next step could take place ... connecting the floppy drive and try to boot.

Unfortunately it won't boot ... the floppy motor didn't start to spin up. I checked the serial signal lines and the control lines from the Mainboard, they all looking good and valid. There must be an issue directly with this old floppy drive ...

Luckily I pick up a defective spare floppy with a working Motor and change it. Voila ... the Motor starts and after some tries I found one working floppy with the correct operating system on it. The Emulator loads his system and ... it stops ... everything freezes ... no button or any function was available.

One word to the floppys ... It is still impossible to write a valid disk for a Emulator I with PC-based Floppy-Drives. Forget OmniFlop ... it's a hardware problem. Even the wonderful KryoFlux Hardware is not able to write a Emulator I disk (it can read this disks, but can't write it). So if you want to boot a Emulator I you are in need of a working E I Floppy- Drive with a working Disk, or you need a SD-Card Floppy Emulator like the one from Lotharek (and a correct boot image on the SD-Card)  .

But back to the repair story ... After the booting and reading it's Operating System the whole Emulator freezes. Once more I take a look at the busses ... and ... after booting and running it's program there are faulty lines again. The cause was a third DMA Controller that are inactive until the boot process has finished.  After replacing this Chip the Emulator boots completly and could be operated through the Frontpanel. This was the first goal ... now it was possible to check all functions and to get an overview of all still existing errors.

During the rework of the housing ... the whole electronic stuff sits in this beautiful Banana-Box. It works quite good, but it was very complicated to get a proper grounding here :o)

After I checked all functions ... the result of the 15V Rail Error show it's ugly face. Seven of the eight voices are not working. After I checked the OP-Amps I found the Filter SSM-Chips as the cause of this. They died as the Power Supply 15V breaks up to 19V.

At this point I decided to replace all 8 SSM Chips with the brandnew SSI-2144. There is one distributor in Europe and he also had some handy piggy-back boards for this SMD-parts. With this piggy boards you can replace the SSM2044 directly with the SSI2144. The only problem is the "extreme" soldering work ... SSI2144 is a fine pitch SMD !

Wow ... all eight voices are working now. But there are still errors ! If I try some of the disks I realized that some sounds had definitely problems during the playback. Shorter sounds still working, but longer samples sound distorted. There must be a issue with the Sample-RAM !

E-MU describes detailed how to solve such memory problems, but they use a special EPROM for that case. Unfortunately such a Debug-EPROM is currently only available for the successor ... the Emulator II not for the Emulator I. Another Road-Block to lift ... try to find the defective RAM Chips manually :o) ...  or you decide to change all of them :o)))))

After replacing all RAM chips all voices worked perfectly ! The rest was pretty standard ... cleaning sliders and pots, change all connectors, upgrade with a Lotharek Floppy Emulator as a second switchable Floppy Drive, solve an issue with the sampling jack and input filter.

What a beautiful machine ... what a beautiful sound !!!

It's definitely worth this effort :o)