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 Emulator I

  

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Created by
 Western Graphics
Last modified
 13 March, 2004
 

Emulator I : Repairs

Overview The Emulator I is on the whole a reliable sampler but age is catching up with many of its components. However the rolled steel casing and some high quality components have kept it alive. The main problem areas are the PSU, the floppy drive, the keyboard, sliders and buttons.

Warning Please only attempt a repair yourself if you are competent at servicing electronics, use a service centre if in doubt. The Emulator is easily damaged or melted by amateur attempts at repair.

Keyboard The Emulator uses a 4 octave Pratt & Read assembly which was very popular in the 1970's for synthesizers without touch sensitivity or the new fangled "after touch" of the 1980's. These keyboards are robust and the contacts are reliable, however you will tend to get a keyboard wave as the individual keys settle down to slightly different heights. You will also find that the keyboard feel is clunky as the bushings age and become hard, and the keys will no longer centre properly.

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click to enlarge image

Luckily these problems can still be sorted even though replacement keyboards are long since gone. The rubber bushings that are under each key can be replaced with new ones. This improves the feel and provides a straight line of centred keys. Here are the details. 
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Floppy Disk Drive  The Emulator uses a full height Shugart SA400L 5.25" SS/DD floppy diskette, with 40 tracks and 180kb/250kb formatted/unformatted capacity. This is a very early floppy drive with a life span of just 5 years !
 
The drive can usually be repaired at a cost of $175+. We have limited stocks of new drives, contact us for details. The original SA400 (from which the L model is based) was the first 5.25" floppy drive in the world, when it was launched in 1976 (it was in production by mid 1977).

Digital to Analog Converters
The Emulator uses 8-bit linear DAC88's which are kinda hard to locate but are still out there.

Filter Chips The Emulator uses SSM2044 analog filter chips, which occasionally fail and take a voice down. These are hard to locate but try
DB Musical Electronics.

 Slider Knobs

Looking for replacement Slider Knobs for your EI ?

They are available from Farnell at
www.farnell.com
part number 766756.
  

 Push Buttons

The Emulator makes use of small momentary push buttons which are the same as used on the Prophet 5.
 

 Fuseholder

fuseholder - not quite the same colours !The Emulator uses a square black external fuse holder, with an internal red lid and fuse. These were made by Littelfuse and are:

Low Profile Snap Mount 15A 250V Part Number 348871
 

 Rotary Pots

The Emulator uses high quality rotary and slider potentiometers which should never need replacing.
 

 Power Supply

The power supply is getting old by now and failure is not uncommon. One of the rails may go out of specification. Replacement PSU's are not available, so the best option is a service centre repair. It is very easy to service as it is made of discrete parts and its not a linear power supply.