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trouble with midimon MTC display


gtxdude

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greetings midiboxers,

i am the resident n00b, this is my first post, so please be gentle...

i hope to build a seq, but thought i would start with a mon to learn more about the platform. i have completed the initial build with the following results:

the core and the display seem to work fine. when powered up, it goes through the usual motions and then i get 4 lines of <no event>. so i think the application software is running fine.

i have built a doutX4 and the octal seven seg display for midi time code. herein  lies the problem. the display never lights. should it after a power up? or does it wait until it receives MTC to light up and begin to display?

i took an oscope and noodled around on the first shift register a bit. the two clocks (SCLK and RCLK, pins 11 & 12) have good looking TTL pulse trains on them (i don't know what they should look like) but at least there is activity. the data input line (SER, pin 14) goes to a TTL high immediately after power up and stays there. there is never any activity on this line at all. is this normal? i have also verified that pins 10 & 16 are high (5v) and pins 8 & 13 are low (gnd).

i am using hardware that i purchased 4 weeks ago from smash. i have loaded the setup_default.hex application file included in the midimon_v2_0b.zip file downloaded from uCapps.

any ideas? many thanks in advance. and also, my thanks to TK and this amazing resource and community. i look forward to becoming a productive member here.

gtxdude

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to the seven seg display: absolutely nothing. continued darkness.

to the LCD: much happiness. midi events are displayed. and if i send MTC, (using sonar v8) the first line displays the time code and the BPM as advertised.

i have done a close visual inspection of the doutX4 and found no problems. the core is working fine.

i guess my question is this: under normal circumstances, when should the seven seg display activate?

thanks for your help stryd.

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strdy, your troubleshooting instincts are spot on. i had two problems: the common anode wiring on J4 was jacked up and i had a rotten solder joint on J1 (on the doutX4). after those problems were sorted it started working just fine.

i have included a pic of my near completed build. now i need to mount this stuff in the enclosure...

i'll upload a pic or two when its done.

thanks strdy!

4803_IMG_0197s_jpgd2ffe73101d450982057d3

4803_IMG_0197s_jpgd2ffe73101d450982057d3

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  • 1 month later...

one thing i noticed was that on the dout board you have got the 2nd 220 ic in its socket, yet on the schematic it calls for that section to be just bridged and no resistors there. basically the links for j4 on the dout board if you look at my dout build  this is what i mean, notice the link wires in place of the resistor array ic chip. if you check the schmatic that stry reffers to http://www.ucapps.de/mbhp/mbhp_doutx4_mtc.pdf  you will see that it says "no resistors 8 bridges"

DSCN6515.jpg

im pretty sure that what its supposed to be like there for the anode link.

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