midiboxLC: testing - how should it behave?

Testing/Troubleshooting
1

Hi folks!

I’ve now finnished most of the parts of my midibox LC and have entered the stage of testing.

I have burned the loader sucessfully using JDM and have uploaded mios 1.7 using midi-ox and then the midiboxLC using serge’s loader. I have connected two of the 402A displays from reichelt and i have checked the display cableconfiguration several times.

How the box behaves:

When I switch on the box the displays light up, but no characters are shown (didn’t test it when there was just mios on it). I tested the displays with no data pins connected and they showed the usual black bars but with very poor contrast (couldn’t improve it with the pot. i could make the characters disappear but couldn’t get better contrast. the backlight voltage also drops quite a lot when the midi-out led on the ltc is active, causing the displays to flicker)

Then the box sends F0 00 00 7E 40 10 01 F7 once (that is correct as far as i understood the resources?!?)

Then it keeps sending random pitchbend data.

  1. When I disconnect the displays it gets faster.

  2. When I ground pin 0-7 of J5 it slows down.

  3. When I connect the four DINS (with no buttons connected) it slows down even more.

… That’s it so far :slight_smile:

I just wan’t to know what could be wrong with my box and how it should behave correctly or if there’s something I should consider.

Thanks a lot in advance!

cheers

rambinator

2

The contrast problem might be that the wallplug psu is to weak with 500mw because it gets worse the more components i connect…

I also uploaded the crc-check-utility and it returns the correct string via sysx but not on the display, that means theres something wrong with the displays but i havent figured out what it could be yet, just tested every connection again.

Is there something i could test at the data pins of j15 with a voltmeter or a scope?

3

Hi folks!

Today I got the displays to work  ;D

The problem was some sort of glue-layer sticking to pin d7 of j15 for some unknown reason. i rubbed it off with a screwdriver and know it works great.

The onlay question remaining at the moment is if the random pitchbend data is something that is normal…

cheers

rambinator

4

The random pitchbend data shouldn’t be happening. Do a forum search “jitter” and you will find out what is wrong. There is heaps of advice on minimising jitter both on ucapps.de and on this forum.

Oh… have you got the eight pots connected? Unconnected pots=random pitchbend data.

5

Thanks a lot, that should be the reason.

I don’t even have the pots yet (I am saving money for alps motorfaders). So my midibox seems to be working  :) and I can begin with the enclosure.