MATRIXSYNTH: E-mu Emulator Original Series 1 Emu Sampler

Monday, September 21, 2020

E-mu Emulator Original Series 1 Emu Sampler

via this auction

"Unit has had a fair bit of maintenance done recently which includes:

-Remove both voice boards, clean all IC sockets with chips removed, and clean ribbon connectors.
-Clean keyboard bus bars and j-wires
-IC swapping to determine voice failures.
-Replace flip flop ICs, replace the one working ROM that I could find. Populate working voices to be the first ones triggered.
-Replace all Tantalum capacitors

Back history:
Emulator booted up and loaded disks, but had 4 corrupt voices that output only garbage, and 2 voices that played attack and release of note when key was pressed and let go, but dropped out over duration of playback. By swapping around socketed chips, I was able to determine four of the AM2812ADC RAMs were malfunctioning, as well as six 74LS273 flip-flop ICs for two voices. I was able to source new 74LS273s, but could only find some old AM2812ADCs for sale on eBay over several months. Out of the five NOS chips I ordered over two months, only one of them worked.

I tested the sampler, and it works. The Truncate, filter, and start work. Those parameters don’t seem to change as the note plays, you have to make changes when the note isn’t playing. At least, that’s what I found. When testing the sampler, one of the Tantalum capacitors blew up. I changed all of the Tantalums on the voice and CPU boards with electrolytics of the same value. There were a total of 17 Tantalum capacitors.

Other noted issues with the Emulator are mechanically loud transformers, and a dent on the side from poor packing when shipped.

To get fully working, you’ll have to find working replacements for the three AM2812ADC ICs. I removed the chips, but they are socketed. When looking at the board with the top open, those RAM install upside down! There’s a white mark on pin 1, and I added some silver paint and a label that says “Top” to the socket. The indention on the top center of the chip indicates the top. There are five working RAMs, and you need three more.

I will include 17 floppy discs as well. I’m not sure if they all correspond to the factory library or are home brew."

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