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SP-12®: Repairs
Overview The SP-12 is on the whole a reliable drum machine, with few mechanical parts and a robust electronic design. The main problem areas are the PSU, the LCD and 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 SP-12 is easily damaged or melted by amateur attempts at repair.
LCD Overview The SP-12 uses the same 16x2 character LCD as the Emulator II. This is an Optrex unit with an EL backlight. When new the
display is bright blue with grey/black characters. The LCD does fade dramatically over time, and the backlight can fail or the inverter that drives it can fail too.
LCD Age After around 2000 hours use the LCD will need
replacement, and its a good idea to replace the LCD whilst parts are still available. You can check when the LCD was manufactured by looking at the code stamped on the back of the LCD in black.
The first 2 characters are the year, and the third character is the month. 85 or 86 is a typical build year.
LCD Viewing Angle The LCD viewing angle can be controlled by
varying the voltage on pin 3. The SP-12 has a preset viewing angle controlled by resistors R1 and R2 on the panel PCB. You will not need to change this.
LCD Part Number The original part number is an Optrex
DMC16207-AE. This is a 16x2 LCD with EL backlight. The physical size is 84x44mm and it uses a standard single row of 14 data connections. E-mu Systems no longer have any spares, and this is
a good job as its expensive from them! The current Optrex part number is DMC16207N-EB, and this LCD is widely available for under $25/£15. Try www.digikey.com.
Optrex DMC16207N-EB Data Sheet
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LCD Inverter The LCD backlight (the blue colour) is driven by a small inverter that generates 100VAC at 400Hz from a 5V supply.
The inverter is a NEC (NEL-D32-46), and its a small black plastic box that sits on the front panel PCB to the right of the LCD. The inverter can fail in which case it need replacing.
LCD Replacement
The LCD can be replaced relatively easily but you will have to remove the front panel PCB and desolder/resolder the 14 way data cable and 2 way backlight cable that connect it
to the front panel. You may also need to file down the PCB to get the LCD to fit as new LCD's don't have sloping corners. Ensure the new LCD face and the LCD transparent cover in the front casing
are both protected whilst your desolder/solder. You may also need to replace the 14 way cable between PCB and LCD, as this is difficult to desolder.
EL Backlight Replacement An easier solution to replacing the
whole LCD is to replace just the EL backlight itself. This works well if you know the characters are working okay but you just cannot read them properly. An added plus is that the black on blue lettering remains, which is easier to read.
Visit www.backlights.co.uk for more details.
The EL backlight is easily removed by unsoldering the two connections on the LCD and then pushing the backlight out using
a credit card. The new backlight can then be slotted in and the connections soldered in place.
Battery The Lithium battery in the SP-12 will last around 5 years. It is bright yellow and located at the rear of the main PCB. When it
fails your songs and the RAM based samples will not be stored after power off. To replace it you need a Panasonic Lithium 2/3 A 3V battery with tags - part number BR-2/3AT-2SP. DigiKey in the USA stock them, the Part # is P201-ND
DAC Chip The SP-12 uses an AD7541 12-bit DAC, which is still widely available. mo
Filter Chips The Emulator SP-12 uses SSM2044 analog filter chips, which occasionally fail and take a voice down. These are hard to locate.re » |
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Slider Knobs |
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Looking for replacement Slider Knobs ?
They are available from Farnell at www.farnell.com part number 766756. |
Small Push Buttons |
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The SP-12 uses a small momentary push button for most of the controls. After 15 years use they are beginning to wear out and even with cleaning still don't work immediately. They
are easily replaced with new buttons made by E-switch and are available from www.digikey.com in the USA.
Colour
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Digikey Part #
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BLUE
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EG2556-ND
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RED
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EG1325-ND
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BLACK
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EG1321-ND
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A full set of buttons will cost around $60, and you can choose from a range of cap colours. You will need to
desolder the old buttons carefully.
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Pad Buttons |
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Replacements can be bought for US$11 from EPR Electronics in the USA. www.eprelectronics.com
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Fuseholder |
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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 |
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The SP-12 uses three front panel potentiometers which tend to grind a bit after 15
years use. They can either be cleaned or better still replaced by a higher quality 10k Log potentiometer. We use nice Bourns Conductive Plastic models with new knobs.
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Power Supply |
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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.
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