Issues connecting a Roland SC-55 to an old 486

Discussion about old sound cards, MIDI devices and sound related accessories.

Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-07 @ 21:49

Hi there,

I am having the weirdest and most annoying issue while trying to make my SC-55 work in my old 486 DOS gaming machine. I am using an ES1868F audio card as the MPU-401 interface, at address 330h (also tried 300h). When connecting my MT-32 via a db-15 to midi cable music is produced without any issue, so the cable seems to be in working order as well as the configuration. However, if I disconect the clable and connect it to the SC-55 midi-in no sound is produced :( I have tried both with and without softmpu loaded in memory with identical results.

Well, that means it's a faulty SC-55 you may think. However, if I connect my laptop to the sc-55 unit through a usb-midi cable I can get sound out of the SC-55 without problems. Through both of the midi-in connections! It's the combination of the db-15 to midi which gives no sound, but the cable works fine with the mt-32. Is there any difference in the way that midi messages are sent through these two cables? I would have thought there is not, but can't figure out what is wrong.

Let's hope some of you have found a similar issue and can help me identify and solve it. Perhaps some misconfiguration of the sc-55?

Thanks in advance! Looking forward to hearing doom soundtrack in all its glory!
Last edited by jsp on 2018-8-08 @ 06:25, edited 1 time in total.
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Re: Issues connecting a Roland SC-55 to an old 486

Postby Kamerat » 2018-8-08 @ 00:43

Are you sure your DB15 to MIDI cable contains the necessary circuitry to get a proper MIDI signal or just route the signal direcly from the DB15? At page 27 there's an example how it should look like.
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Re: Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-08 @ 06:25

I really doubt my cable contains any electronics beyond the pure copper wires. And yet, it works fine with the mt-32 which for me was ruling out it was a cable issue. I may try to get another to give this a go, any suggestions on where to pick it? Last time I ordered from aliexpress :(
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Re: Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-08 @ 07:42

Thanks @keropi, just ordered one. I'm still unsure this is the problem but it's worth a try, and anyway I wanted to have a spare cable :)
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Re: Issues connecting a Roland SC-55 to an old 486

Postby derSammler » 2018-8-08 @ 07:46

What games/software are you using?

Also, how's the audio output of the SC-55 connected? If you have routed it through the sound card's line-in, make sure it's not muted.
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Re: Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-08 @ 08:10

I tried several games, including doom2 and tetris classic. Doom2 is especially nice to setup, allowing you to select the midi port address.

The output from the sc-55 is connected to my external mixer. This mixer is connected my amplifier, but it also has a headphone output I was using for the test. I also tried the headphone output in the sc-55 unit to isolate the cause of the problem, and still no sound.

The front panel of the unit looked pretty still, really as if it was not getting any midi input. However, while playing Doom2 I could plug the lead to the MT-32 and listen to the music, unplug it and connect it to the sc-55 and it would remain silent. Plug it again to the mt-32 and again music.

So weird, it may something related to the cable after all. I'll have to wait and see if the new cable works. A funny thing I noticed is that the MT-32 would not work if I routed the midi signal from the input of the sc-55 to the mt-32 through the midi-through port. It's really as if the sc-55 was firewalling any midi input coming from my 486 :(
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Re: Issues connecting a Roland SC-55 to an old 486

Postby derSammler » 2018-8-08 @ 08:13

Did you already try resetting the SC-55 to factory values? Does it play the built-in demo song?
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Re: Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-08 @ 08:22

Yup, I did init it by switching it on having both instrument left and right keys pressed. The demo songs play well. Hell, I can play midi files from my laptop using the usb<->midi cable. It's the 486 that won't be able to play music through it via the db15<->midi cable, but it would play the mt-32 fine. Crazy!
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Re: Issues connecting a Roland SC-55 to an old 486

Postby Srandista » 2018-8-08 @ 14:21


Thank you for letting me know about this! I was going to buy some on eBay, but for one, you cannot be sure, that it will work properly with MIDI and also, strangely, they're not that cheap on eBay.
My overkill "retro" PC - Pentium E6500K, 512MB/2GB RAM, Radeon 9500@9700 (Softmod), 80GB HDD, Win 98/XP
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Re: Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-10 @ 15:02

Ok, I got my setup working using the following hack: I connected the db15-midi cable directly to my mt-32, and used the midi-through of the mt-32 to feed the sc-55. Worked like a charm! The cable is obviously missing some electronics but the mt-32 copes with that pretty diligently.

On a related note, Doom 2 soundtrack sounds just beautiful on the sc-55!

Thanks to everybody that suggested solutions. I'm now waiting for the new cable which I hope will be able to drive the sc-55 properly (will confirm when I get it). I may end up sticking to this solution anyway.
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Re: Issues connecting a Roland SC-55 to an old 486

Postby misterjones » 2018-8-12 @ 02:24

Definitely sounds like a bad midi cable. It could be the gp-to-midi cable too. I had one go out on me and it took a good while to figure it out.
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Re: Issues connecting a Roland SC-55 to an old 486

Postby jsp » 2018-8-13 @ 10:53

Alright, got my cable today ordered from https://www.serdashop.com/JoystickMIDICable and I can confirm it works perfectly fine when connected directly to my sc-55. So mistery solved, it was the cable! I am still amazed of the ability of the mt-32 unit to deal with such an imperfect cable and even deliver a compatible midi signal via the midi-through port to my sc-55. Neat.

Thanks @keropi for sharing the link to the compatible cable.

Cheers
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Re: Issues connecting a Roland SC-55 to an old 486

Postby keropi » 2018-8-13 @ 11:09

Excellent news, glad all worked out in the end!
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