Need(ed) Some Troubleshooting Help! (ART SGX200)

[Paul Marossy]

OK, I have an ART SGX-2000 and the X-15 foot controller. For some reason, the foot controller will no longer switch banks. But everything else on the foot controller functions as it should. I have verified that my MIDI cables are good. So, that means that there is either a problem with that section in the SGX-2000 or the X-15.

The schematics are a little complicated for me, though. Can anyone help me narrow things down on where to look?!

SGX-2000 Schematic
X-15 Foot Controller

Any help much appreciated!  

[Paul Marossy]

BTW, SW-2 & SW-9 on the X-15 schematic are the ones that are supposed to control the banks up or down. Both of those little tactile switches appear to be functional as well...

[Paul Marossy]

No bites? I thought some digital guru might have some ideas...  :?

[Paul Marossy]

Just in case this may help someone in the future, the problem appears to be narrowed down somewhat.

Last night I checked the continuity of all the interconnective wiring, MIDI jacks, and if the tactile switches work as they should - I found nothing. However, SW2 & SW9 share a bus line called KSCAN-7, along with two other switches, SW6 & SW13 and none of these switches appear be operational. I am guessing that there is either a problem with the common connection(s) between these switches, U6 is faulty or there is something wrong with the +5V power supply to those particular switches.

I also thought of two other things:
1. what if the LED on SW6 or SW13 burned out? Would it freak out like this?
2. What if the lithium battery in the main unit was dead? Would it have any affect?

If I don't find anything fishy tonight in the X-15, I guess I'm going to do a factory reset on the SGX2000 and see if that helps any.

[David]

Paul:

Check that battery before you do anything else.  I have a GT-3 now, and urban legend suggests that the battery is the first point of failure.

[Paul Marossy]

Paul:

Check that battery before you do anything else.  I have a GT-3 now, and urban legend suggests that the battery is the first point of failure.

Yeah, a couple of people have suggested that I do the same. It's on the list of things to do today!

I messed with it some more last night, and I can not find anything wrong in the X-15 with the switches, continuity between them or the power supply - I thought I was onto something a couple of times, but it turned out to be nothing. I did a factory reset on the SGX2000, too. As far as I can tell, the LEDs are all functional (none are burned out).

I do know that the lithium battery in the SGX2000 is most likely dead. I don't know if it could affect the operation of switching banks, but I guess I need to change it since it's been in that unit probably since 1992! I'll try changing the battery and see what happens.

The funny thing about all of this is that the bank switching never worked right. Maybe the battery was already dying back at that time?  :?

[Paul Marossy]

WOO HOO!!! Good news, it's fixed! I removed U6 and U9 put a socket in their place with new 74HC244s, and now it works. I am really happy about this!!! Ahem, anyways, thanks for the help.  

[mojotron]

WOO HOO!!! Good news, it's fixed! I removed U6 and U9 put a socket in their place with new 74HC244s, and now it works. I am really happy about this!!! Ahem, anyways, thanks for the help.  

That's great news Paul. I had an ART MachII (From a long time ago..) that I debugged several times. One thing that really gets to me about how ART built these is the widespread use of internal ribon cables to hook into IC's :evil: and then between boards  :evil:  :evil:  

Mechanically, there is no way to keep these from failing with use - any shock will shake them loose - one pin at a time  :evil:  :evil:  :evil: . So when I start trouble shooting I start with the ribbon cables.

[Paul Marossy]

So when I start trouble shooting I start with the ribbon cables.

That was the first place I started, the continuity between the ribbon cable connections and the switches. The X-15 seems to be well designed in terms of keeping all the PCBs secure inside of the enclosure.