E-mu Emulator Sampler User Forum for the EIII EII EI and EIII XP - EII+HD - What circuit board is this?

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Author Topic: EII+HD - What circuit board is this?  (Read 5427 times)
reginator
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« on: April 04, 2018, 02:39:38 PM »

Hi all,

I'm cleaning and updating my new EII+HD and trying to gain general knowledge of the PCB's inside.

I can identify the output PCB, digital PCB, Adaptec SCSI PCB, and the SCSI Interface PCB (easy to be hard)... but there is also an unidentified hand-wired circuit board sitting on top of the output board.

The hand-wired circuit board and the associated wiring appears to be the same age as the EII.

Also, the serial number of the EII+HD appears to be someones name instead of a series of numbers.

Any ideas what this circuit board might be?



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alka
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« Reply #1 on: April 05, 2018, 09:49:47 AM »

interesting! have no idea.. never seen this either.
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dfiorucci
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« Reply #2 on: June 30, 2018, 05:36:48 PM »

I remember back in the day probably around 1987 there was a guy out of San Diego that was advertising in the back of Keyboard Player some different upgrades for the Emulator II and one of them was stereo out don't remember what the other options where but maybe this is one of his upgrade boards.
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reginator
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« Reply #3 on: July 01, 2018, 01:40:27 PM »

I remember back in the day probably around 1987 there was a guy out of San Diego that was advertising in the back of Keyboard Player some different upgrades for the Emulator II and one of them was stereo out don't remember what the other options where but maybe this is one of his upgrade boards.

My friend, you are correct. This board is wired to two additional output jacks on the back. I tested them with my oscilloscope a few weeks ago and indeed there was an audio signal there- and they were stereo!

There's also a switch attached to the floppy drive and it's hardwired to the add-on board. It doesn't appear to do anything that I can detect. I'll search google to see if I can come up with something about it.

Thanks dfiorucci
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dfiorucci
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« Reply #4 on: July 03, 2018, 10:23:30 PM »

I'm thinking the switch is for  a pad boost or cut for the stereo outs.
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reginator
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« Reply #5 on: July 05, 2018, 11:38:46 AM »

Boost or cut is probably right. I'll check for a difference in levels tomorrow.
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dfiorucci
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« Reply #6 on: July 05, 2018, 07:35:52 PM »

I did come across a pic in this forum of the psuedo stereo output board from the guy from San Diego.
This is not it.
From what I can tell from the picture all 8 outputs are being tapped and sent to the high speed quad monolithic spst cmos analog switch then it looks they are being summed in split into true stereo.

Did you happen to buy this Emulator II + HD from the midwest because if so I might know the tech that did this board.
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reginator
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« Reply #7 on: July 06, 2018, 02:02:02 PM »

I bought it from my friend in Florida, although I'm not sure where he got it.

This EII does have a peculiar serial number: KACHER

Maybe this gives a clue to if it was modded in San Diego.

I can take more photos of the stereo board if needed.


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dfiorucci
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« Reply #8 on: July 08, 2018, 03:23:15 PM »

Yeah probably not the one I'm thinking of.
Doesn't look like the guy from San Diegos stuff either.
He did actual circuit boards not to say this wasn't an early breadboard concept.
Do you get true stereo out from that?
If so it would be cool to document and possibly replicate on an actual circuit board design.
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reginator
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« Reply #9 on: July 09, 2018, 01:23:46 PM »

I'll perform some audio experiments to see how it performs as compared with the eight separate outputs.

I'll post my finding here.
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seamonkey
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« Reply #10 on: July 31, 2018, 03:09:47 PM »

I bought it from my friend in Florida, although I'm not sure where he got it.

This EII does have a peculiar serial number: KACHER

Maybe this gives a clue to if it was modded in San Diego.

I can take more photos of the stereo board if needed.

I'm the guy he bought it from and I lived in the Midwest, but I bought it online used in 2010 from Noisebug in Pomona, CA.
Interesting about the wiring and stereo outs, who knew?Huh all that time I had it...

Good to see you in here Reg, I stopped by for old times sake, actually was going to close my account but glad I didn't.
Yeah that no serial number thing still baffles me. I still think it was someone in development or something at Emu.
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dfiorucci
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« Reply #11 on: July 31, 2018, 05:38:02 PM »

Very cool,
I thought this had belonged once to guy in Wichita Kansas and had been modded by a tech there Jeff Rainer.
Guess not.
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reginator
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« Reply #12 on: August 01, 2018, 12:55:47 AM »

Hey Rick, good to see you're still here.

The EII is happily churning out sounds.

One of the last things I did was cleaned the metal contacts on all the buttons.

I'll probably rebuild the power supply at the end of this project- just to ensure continued stability and longevity.
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