E-MU EMULATOR II+ Work Log

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Re: E-MU EMULATOR II+ Work Log

Postby Reginator » Thu Aug 30, 2018 10:58 pm

Again, nice work!
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Re: E-MU EMULATOR II+ Work Log

Postby azone » Sun Sep 02, 2018 8:57 am

Worst condition EII I've ever seen!
I registered just to follow and contribute to this thread. I've restored several EII's among other and it looks like you have the knowledge and skills and doing a great job. A few notes.

1) Great decision replacing the original power supply with the Mean Well RT-65C. I use a modified PT-65 along with a custom PCB to achieve same spec as original PSU (incl. power for floppies etc..) and post-regulate etc.. but it's not necessary, the RT-65C will work just fine, and the 500mA-rated -15V rail is fine for the EII requirements . The original PSU is inefficient and the output board underneath gets much too hot. It needs to go.

2) Some folks don't like to change all the logic IC's pre-emptively. Sometimes I agree, sometimes I don't. It depends on the synth and the condition. In your case I would replace all. It's not rocket science replacing the parts but you just have to be ultra-careful selecting the correct family of parts (CMOS vs TTL, LS/HC vs HCT etc...). Best case is to use the same family/spec as the original part for each designation.

3) For PCB's in the condition of yours I would replace the IC sockets. The leaf-spring sockets aren't desirable to being with - you're asking for trouble in that condition. I would use new high-quality leaf-spring sockets or machined sockets if you're willing to finesse the IC's into place.

4) I'm sure you already know - the original jacks (Switchcraft), switches (E-switch), knobs & slider caps (Sifam) etc.. are still in production and can be purchased new.

I'm in the process of painting an EII shell. I've never had to re-finish one before so this is the first time. I have RAL and Pantone color books and will start by matching as close as possible. If you're painting yours please advise what color is used and how it came out. I will do the same.
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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Sun Sep 02, 2018 4:13 pm

Reginator wrote:Again, nice work!


Thanks :2cool:
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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Sun Sep 02, 2018 5:46 pm

Hi Azone.

Yup its a sick puppy, but its getting better :)
Thanks for helping out, thats very cool.

About the power supply, I use a RT125B and a separate switcher for the +/- 15v.
I could not find the RT65C since its discontinued. I will use a buck step down regulator to get the +15v to around 13.4v.

As you said, its probably best to replace the glue logic chips. Need to make a parts list.
Will change all the bad sockets. Looks like the corrosion stops halfway up the digital board. There actually is some shiny sockets on the board =D>

Yes I have new jacks and switches. I also bought new knobs since one of the old was missing the cap. The slider caps I will reuse.
I wont be painting the shell. At least not until someone remakes a Emu II + dekal sett. I like the battlescar look, its had a hard life =). But pls share your paint choices when your ready.

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Re: E-MU EMULATOR II+ Work Log

Postby azone » Mon Sep 03, 2018 7:45 am

...sounds good.
Regarding EII overlay, I see you have a II+ - There's some EII overlays here:
https://www.ebay.com/itm/E-MU-Emulator- ... 3343583204
These are excellent quality. They are dead nuts on, the 10mil polyester material is the same exact spec as the original part but I find it is ever-so-slightly higher quality than the original part and 'pops' a little more.

The older Mean Well T60 was replaced with the the T65 (PT-65 & RT-65). The T-65 is a current part (it's used in lots of current-day analog synths.. DSI etc..). I made a PCB that is the same size as the original PSU PCB. It has a place for the RT-65C. I added regulators for each of the rails. The T-65's have a trimmer to calibrate the +5/+15 supplies. I adjust some components and the trimmer to give +6V and +15V and use LDO's for the +13.2V and +5V rails. I also modify the -15V for -16V and use LDO for -15V. This gives improved performance regarding ripple/noise, although it's not really necessary as the EII is 90% digital running off the 5V. It does have analog filters that runs off the +13.2V/-15V rails but performance should be fine as the rails are not used directly for any important voltage references for any analog or the DAC. This new power supply runs extremely efficient is not anywhere near as hot as the original.
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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Mon Sep 03, 2018 8:02 pm

Yes those overlays looks to be very high quality, just a shame they dont make the + edition. Anyways the cosmetics doesn't really matter without a functioning unit so that's pri one =)

Your right about the psu. I didn't look good enough at the the parts number. I hindsight my setup is way overkill. I was duped by the Delta psu that had 10A for the 5v rail :lol:

Have you measured the current draw on the analog rails? I was testing on the load at 1A, but I was thinking maybe half that. The heatsinks on the local regulators are pretty small, I will look in the parts bin for something better.

Hehe I was checking prices for the 74 logic chips, its gonna be a pretty penny replacing all of them =)

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Re: E-MU EMULATOR II+ Work Log

Postby azone » Tue Sep 04, 2018 10:19 am

Emulator II Power Consumption:
+13.2V @ 540mA (incl. two floppy drives powered directly from 13.2V)
-15V @ 220mA
+5V @ 4A

Total Power Consumption about 32W.

Please note these are these are exact power consumption from direct calibrated rails from bench supply and does not include any losses from the power supply itself. Typical power consumption from the AC outlet will be around 58W for the stock power supply and about 42W for modern SMPS. Also, in my case I post-regulate the rails from the SMPS so the Meanwell RT-65 is pretty taxed on the +5V rail, not a lot of headroom.. I recently designed a new drop-in PSU replacement for the EII's that supports both EII PSU versions. It's based on the Mean Well RT-85C.
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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Tue Sep 04, 2018 8:17 pm

Thanks Azone that's very handy to have :)
Will your new psu have all the rails in one unit? I'd guess the +15v rail could supply 13.2v and the 12v rail.
I compiled a list of chips from the digital board and sent it off for a quote. I need to make a shelf for the +/- 15 switcher psu. Anyone have a source for them brass screw inserts that are pressed into the shell? I'm missing two.

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Re: E-MU EMULATOR II+ Work Log

Postby Reginator » Wed Sep 05, 2018 9:15 am

AlphaC wrote:Anyone have a source for them brass screw inserts that are pressed into the shell? I'm missing two.

AlphaC


I also need one of those for my EII. I haven't checked the size of the insert yet, but I buy 90% of all my hardware from McMaster-Carr. They have nearly anything you need for anything you're working on.

https://www.mcmaster.com
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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Wed Sep 05, 2018 7:31 pm

Thanks Reginator I will have a looksie.

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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Wed Sep 05, 2018 7:45 pm

Wheel wiring harness done.

Image

I have also ordered the Image for the Digital board sans some of the dynamic ram, only 11 available at the time.

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Re: E-MU EMULATOR II+ Work Log

Postby azone » Thu Sep 06, 2018 8:17 am

The inserts for mounting the PCB's to panel are 6-32 brass inserts. They are mold-in inserts, inserted during molding of the enclosure (the enclosure appears to be ABS + 50% fiberglass (or other other bulk-molding compound w/ glass).
The inserts are about 4.25mm tall. Also, it's not common to see but they looks to me like they may even be cut during a secondary process to get them to a shorter/correct height.
The ones on on the ends to hold the bottom panel are 8-32 brass inserts.

Image
Image

I also found these pics below for some inspiration.
There are many ways to remove overlays w/ 3M 467-type adhesive but here's what I do.
1) Use heat gun to heat up the overlay to soften the adhesive to try to get as much as it as you can up along with the label. I don't like getting my EII panels too hot but I do get them up there... but never much luck making it easier. For some adhesives it does wonder, not usually in this case.

Image
Image

2) I use solvents to remove the residue. It's laborious and need to be careful but my experience always brings me back to this approach. I'll usually start with the 'weakest' solution I can get away with.. usually I'll go from 99% isopropyl to acetone, to MEK (yikes). I always try to get away with alcohol as it won't eat the paint finish. In the case of the EII I only use 99% isopropyl, a few fingernails, perhaps a plastic scraper, a few towels (don't tell your wife) and about 2 hours. Make the top panel surface even and liberally put the alcohol on it and wait a few minutes for it to soak in (don't wait until it evaporates). Scrape and wipe and keep repeating until it's all off.

Image

3) Done!

Image
Image
Image
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Re: E-MU EMULATOR II+ Work Log

Postby AlphaC » Thu Sep 06, 2018 8:49 pm

Wow nice tutorial Azone =) That might come in handy later. I have begun the search for injection molding inserts. Thanks to your measurements that should not be to hard (famous last words) :lol:
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Re: E-MU EMULATOR II+ Work Log

Postby Reginator » Fri Sep 07, 2018 10:52 am

I concur - really nice work Azone.

Did you repaint it? What paint did you use?
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Re: E-MU EMULATOR II+ Work Log

Postby azone » Sat Sep 08, 2018 10:05 am

Reginator wrote:Did you repaint it? What paint did you use?

I've never painted an EII. I have one now that I'm looking to repaint. If I have it done I'll match the color and texture of the original paint. I'll follow up here if/when it gets done.

AlphaC I found these PCB's I made years ago for the EMuSer. I have a stack of them. If you decide to install it you can have one.
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