Roland SC-55 MkII midi input problem

[Hopeapaa]

Hello all,

I have a problem with Roland Sound Canvas SC-55 Mark II:
The module doesn't use midi inputs 1 and 2 simultaneously, when the selector switch in the back of the module is set to "midi".

I know, that when "computer" is used in the selector switch instead of "midi", there is no sound output from midi input 1, if computer midi settings are not set as "midi passthrough" etc. But now I have keyboard in Midi input 2 and computer (Roland MPU-IPC-T) in Midi input 1 (back of the module), I should be able to play "together with the midi playback" from the attached keyboard.

This even worked for a while, but when I plugged the power off the wall and then put it back (module was totally off, so no stand by etc.) it stopped working. I have just purchased the module, and not 100% certain how to control the inputs. I am able to use either midi 1 or 2 by swithing their functionality in the menu (all + <part>), but even then the functionality is not dead sharp what is written in the manual: the midi input 1 always is sent to midi through, not ever from midi 2 (no matter how input switching is set).

Any help on this? Any setting I need to try?

Thanks in advance.

[Cloudschatze]

MIDI IN1 <--> IN2 needs to be turned off, followed by power-cycling the module to activate the setting. You can either turn it off manually, or just perform a factory reset ("Power on while holding both INSTRUMENT buttons, then press ALL").

[Hopeapaa]

Thanks for the reply, but unfortunately this didn't help.

This is how it's working:
1) In1 <-> In2 = Off (default)
-Midi from In2 is played, In1 is forwarded to midi through without playback

2) In1 <-> In2 = On (with boot to activate setting)
-Midi from In2 is not played or forwarded anywhere
-In1 midi is played and also forwarded to midi through

Strange. I have one conclusion, which is that the selector switch is broken and it really doesn't change to setting "midi" at all. This would explain the behaviour somehow, except the midi from In1 always forwarded to midi through, even if In1 and In2 functionality are swapped...

[Cloudschatze]

I have one conclusion, which is that the selector switch is broken and it really doesn't change to setting "midi" at all.

Could be, or perhaps it's just dirty. In the manual, the signal flow at the bottom of page 14 shows the behavior you describe. So, despite being set to "MIDI," the switch might still be stuck on the "RS232C-2" setting.

I'll check the service notes later tonight. I seem to recall that the procedure for testing the switch will display the respective setting on the LCD.

[Cloudschatze]

Try this:

With the SC in STANDBY, press and hold both INSTRUMENT buttons, and simultaneously press both KEY SHIFT buttons. The unit should power-on in Test Mode. If your SC-55mkII is like mine, this might take you a few tries...

While holding the INSTRUMENT > button, press the < KEY SHIFT button. This skips ahead to the MIDI and battery test. In the upper-right corner, the switch position will be displayed. If it's currently set to "MIDI," that's what you ought to see.

[Hopeapaa]

Great thanks! Some tools for analysis are always welcome.

I will try this when I get back at home from work.

[Hopeapaa]

Ok, now I checked the switch position with the Test Mode:
-result is, that switch position really doesn't change, as the behavior indicated.
-The setting is stuck at "RS232-C1"

Has anyone experienced anything similar? You Cloudschatze thought it might be just dirty: do You know if  I can damage anything just by using some electornics cleaning spray as first aid?

[Cloudschatze]

You Cloudschatze thought it might be just dirty: do You know if  I can damage anything just by using some electornics cleaning spray as first aid?

Simply sliding the switch back and forth a few times (with the unit unplugged) ought to clear any oxidation well enough. I'd try that before considering the use of any contact cleaner.

[Hopeapaa]

Hmm, I tried contact cleaner after sliding switch back and forth didn't seem to do anything. I finally got the state to change in between 232C-1 and 232C-2, but all the computer settings gave 232C-1 and midi-position gave 232C-2.

The switch might have gone bad, because it also sometimes keeps on changing in between 232C-1 and 232C-2 by itself when in the position "midi". Most of the time gives only 232C-1, but with some moving or slight pressure might give 232C-2.

Darn...

I suppose the switch is soldered to the main board, and might be that I just try to live with the problem with swapping In1 and In2 as needed. Is the switch part number mentioned in the service manual if I try to find replacement?

Edit: one more thing, if anyone has schematics for main board, I could fixedly connect the switch position to midi, since I really don't know why anyone would like to use non-standard serial connection... (with Amiga etc.?)

[Cloudschatze]

Is the switch part number mentioned in the service manual if I try to find replacement?

The Roland part number is #13159363, with the model listed as "SSSF124-S09N-1". Shouldn't be too expensive. (<$4.00 USD)

... if anyone has schematics for main board, I could fixedly connect the switch position to midi...

The actual pinout for the switch (12 pins!) isn't listed in the service notes. I'll have to look over the schematics again, but simply removing the switch might defeat it (since the MIDI In signal is not passed through it).

[Hopeapaa]

Huge thanks for the information.

I sent a request to local Roland Repair/Service with the information and part reference number, unfortunately they are on summer break until end of August. I hope I'll get some answer and possibly the replacement part after that.

I might also check with the local electornics part distribution company, I they have any sources for that kind of swith...

[Hopeapaa]

Now the replacement part arrived in local official repair store, Roughly 2.50,- dollars. More than 30 bucks for the work though.

I think I'll still take the unit for repair, since I don't have a soldering iron at home, and at work I never have time for such stuff anymore.

I'll make a report after my MkII is fixed, so in same situation You get the idea if it's fixable by swithich the switch ;-).

[Hopeapaa]

I'll make a report after my MkII is fixed, so in same situation You get the idea if it's fixable by swithich the switch ;-).

Time for a report, unfortunately not final though:

The switch in the backpanel was changed, and... no effect. The state still didn't change from 232C-1/2 to midi. Those two states could only be chosen and still the state keeps swapping by itself in some positions... Seems that the unit is more or less defective what comes to interpreting the position of the computer switch.

I left the unit in the store for more detailed analysis... Will not spend too much more in it though...

[Cloudschatze]

Seems that the unit is more or less defective what comes to interpreting the position of the computer switch.

I'm sorry to hear that, especially since the switch seemed the most likely culprit.   

Does the repair shop have access to the service notes? They should be able to work through the troubleshooting flow diagrams and positively identify the bad component(s).

[Hopeapaa]

Does the repair shop have access to the service notes? They should be able to work through the troubleshooting flow diagrams and positively identify the bad component(s).

I think they will get the service notes from Roland. Hey, do You happen to have that paper in bits? If yes, could You mail it to me? (hopeapaa (at) gmail-com) Would be nice to know something when consulting the repair shop.

Edit: now it works! There had been one defective contact on the mainboard, basically one connector had been cut somehow. Cannot imagine how that had happened, but with a small piece of wire it  was fixed.

Phew!