MB-6582 -- No Main Menu -- Flashing Matrix and a stuck note on boot

MIDIbox SID
1

Ok, I finished my first MB-6582, but I have some issues.

I have all the chips installed, but only one PIC installed right now.

Ths first issue is when it boots up, it goes to the Modulation M4 screen, not the Main Screen like the user manual says.

The second issue is the matrix leds flash a cross in a steady flashing pattern.

The third issue is, when it boots up the middle C tone is stuck, but if I send it a middle C it stops playing it.

Here is a pic.  This picture was taken when the flashing cross was lit, so you can see it and the screen.

http://www.voodooengineering.com/mb-6582/20081017.jpg

Pressing the Menu button does not take me back to the main screen.

All the buttons seem to work, they click and change things.

Except the Mod  (Sync,Ring) button, which doesn’t seem to do anything.  But it does have a click.

Does anyone have any ideas on what I can check?

Should I install the other three pic chips?

Thanks in advance.

Chuck

2

Having a look at the switch matrix, all your symptoms are explained by the DIN input for that row always being “grounded”… look at the list of switches on that row: Osc Sync/Ring, Mod Osc 1 PW, Mod Src 4, Menu, Down, Select 4, SID 1, Play… i.e. regardless of the currently selected “column” of the matrix, the DIN input is always low and therefore the app thinks all those buttons are pressed.

The flashing cross is what you would get if you pressed Mod Src 4 with Mod Osc 1 PW… the corresponding row and column will flash while you make the selection and then stop after you release the buttons. The display would also jump to the Modulation M4 screen. The stuck Middle C tone is because the Play button considered pressed.

It might be the LCD shorting it, try unmounting it.

However, my prediction is a short between/near the 74HC165 pins.

See attached pic. That’s where I think there’s a short, since that’s where ground and that pin/track are closest.

3891lookforshortherepng36fd6e5d0e033a0b5bfb19cb93798be5
3891lookforshortherepng36fd6e5d0e033a0b5bfb19cb93798be5696×672 48.8 KB

3891lookforshortherepng36fd6e5d0e033a0b5bfb19cb93798be5
3891lookforshortherepng36fd6e5d0e033a0b5bfb19cb93798be5696×672 48.8 KB

3

Wilba,

Thanks man!!!

I loosened the LCD and slipped some paper between it and the control board and now all those problems are gone.

It comes up with the E002|A001 screen just like the manual says.

No stuck middle C, No flashing matrix cross.

Thanks a ton for pointing out the problem.

Chuck

4

Looking good btw…

If you’re crafty enough, cut a piece of 3mm acrylic/perspex between the panel and LCD… this fills the gap nicely.