EII+HD - What circuit board is this?

[reginator]

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?

[alka]

interesting! have no idea.. never seen this either.

[dfiorucci]

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.

[reginator]

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

[dfiorucci]

I'm thinking the switch is for  a pad boost or cut for the stereo outs.

[reginator]

Boost or cut is probably right. I'll check for a difference in levels tomorrow.

[dfiorucci]

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.

[reginator]

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.

[dfiorucci]

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.

[reginator]

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

I'll post my finding here.

[seamonkey]

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? 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.

[dfiorucci]

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.

[reginator]

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.