Need help troubleshooting MBFM fault

LeTran · December 23, 2009, 6:44pm

Hi folks I’ve been following Midibox for a while now and have just completed my MBFM module :rolleyes:

However, it doesn’t work… :sad:

I have uploaded MIOS successfully to my core and I seem to get favourable responses from MIOS studio. I have uploaded the test tone program which appears to complete successfully. When I listen on the outputs I have nothing.

I have tested all the voltages and they appear fine (I’m doing the 0v linking of the 5v PSU and 12/-12v PSU).

I have put a scope probe on the inputs to the YMF262 and they all appear the same - the same as the clock freq ??!

Are there any steps I can take to narrow down the fault ?

Thanks alot.

fussylizard · December 23, 2009, 7:36pm

Make sure the wires from the Core to the OPL board are < 10 cm in length. Wilba had issues with longer lengths.

I tried making a special cable to avoid soldering to the bottom side of the board but it was a pain to debug and the OPL was a bit temperamental. Soldering straight to the bottom of the core (like the instructions say!) seemed to work better.

Good luck!

LeTran · December 23, 2009, 7:57pm

Thank you - they are about 20cm in length on ribbon cable, maybe that’s a bit too long? I also fixed up the LCD display and it displays the MIOS version and then states OPL3 testtone generator so I think the core is working properly.

What kind of tests can I do to see if my YMF262 chip is blown or not ?

thanks alot,

nILS · December 23, 2009, 9:21pm

maybe that’s a bit too long?

Quite likely.

What kind of tests can I do to see if my YMF262 chip is blown or not ?

Shorten the cables

Shuriken · December 25, 2009, 11:11am

Do you hear the opamps make a popping noise when u turn your MBFM on?

LeTran · December 25, 2009, 3:58pm

Yes they do make a slight popping sound. I guess that proves they’re OK ?

Thanks for the tip on shortening the cables - I will try that after Christmas and let you know how I get on !

Happy Christmas to all yall.

LeTran · December 29, 2009, 11:03am

Today I shortened the cables but unfortunately it’s made no difference.

Well I say no difference, in fact the LCD won’t display it’s usual MIOS intro etc. If I uncouple the OPL3 module it displays fine.

Could something on the OPL3 board be the cause ?

I have another YMF262 chip so I’ll try swapping it over and see what happens…

UPDATE: Still the same with a new YMF262 chip. Are there any jumpers I need to check ?

LeTran · December 29, 2009, 1:09pm

One other question - I’d like to send modulation wheel data [b0 00 00] etc but how can I type that in the MIOS sysex send window ?

The keyboard control is too sensitive.

It’s for running the interconnection app.

Thank you,

T.K · December 29, 2009, 1:30pm

Unfortunately Java doesn’t allow to send common MIDI events in SysEx packages.

So, you have to find another solution, e.g. you could use MIDI-Ox (if you are using Windows) or MIDI-Pipe (if you are using MacOS)

This remembers me, that I wanted to add an alternative control to this application (e.g. switching pins via MIDI keyboard)

Best Regards, Thorsten.

T.K · December 29, 2009, 1:44pm

Could you please do me a favor and check the most recent mbfm_interconnection_test_v1d release?

-> http://www.ucapps.de/mios_download.html

I added the code which allows to control the pins with a virtual MIDI keyboard w/o testing it… it was the fastest solution to solve this issue.

Please let me know if it works.

C : Pin J2_1:RS = 5V
C#: Pin J2_1:A0 = 5V
D : Pin J2_1:A1 = 5V
D#: Pin J2_1:WR = 5V
E : Pin J2_1:D0 = 5V
F : Pin J2_1:D1 = 5V
F#: Pin J2_2:D2 = 5V
G : Pin J2_2:D3 = 5V
G#: Pin J2_2:D4 = 5V
A : Pin J2_2:D5 = 5V
A#: Pin J2_2:D6 = 5V
B : Pin J2_2:D7 = 5V

(the octave doesn't matter)
[/code]









Best Regards, Thorsten.

LeTran · December 29, 2009, 3:57pm

Thanks TK - but I’m afraid it doesn’t work.

I can only send modulation data on CH16 (not sure if this is correct or how to change) but pressing keys makes no difference.

The mod wheel still works though.

EDIT: Actually I’m only looking at the LCD display so if that part of the code isn’t changed it may still work. I’ll test properly.

LeTran · December 29, 2009, 4:27pm

Tested properly with meter TK but it doesn’t work I’m afraid.

However, if you set the modulation wheel to give something other than RS, pressing any key reverts it back to RS.

Hope this helps,

regards,

LeTran · December 29, 2009, 4:40pm

I tested the core with MIDI-OX and it works fine.

TK if you do make a change to the interconnections prog then I’ll happily test again.

Looks like my problem of dead OPL3 unit could be down to a second dead YMF262 chip ?

I was so careful to get those pins off though !

If anyone else has been down this road and can offer tips to try I’d be grateful. Thanks for the suggestions so far.

LeTran · December 29, 2009, 5:03pm

If I remove the power +5v from J1 on the OPL3 board the LED still glows at about half the brightness.

Is this normal ?

I’ve loaded up the MBFM software and with it set to the default, rhodes piano on CH1 I get +4.09v on pins D2, D4, D5.

Is this correct ?

thanks,

T.K · December 29, 2009, 5:09pm

TK if you do make a change to the interconnections prog then I’ll happily test again.

So, does it mean that you are able to control the pins with the virtual MIDI keyboard of MIOS Studio as well?

This would be great - I will change the other test application as well if it works.

Looks like my problem of dead OPL3 unit could be down to a second dead YMF262 chip ?

I was so careful to get those pins off though !

Thats hard to determine.

If I remove the power +5v from J1 on the OPL3 board the LED still glows at about half the brightness.

Thats strange - it seems that there is a short between the data pins which leads to higher power consumption.

It’s hard to say, if this is related to your soldering work, or if it’s an internal short inside the OPL3 chip.

I’ve loaded up the MBFM software and with it set to the default, rhodes piano on CH1 I get +4.09v on pins D2, D4, D5.

Is this correct ?

The data pins are toggled with high frequency, you cannot measure the correct voltage w/o a scope.

Therefore the test application supplies static voltages.

With the interconnection test, do you always read 5V on the selected pin, and 0V on all other pins? This would help to exclude a short.

Best Regards, Thorsten.

LeTran · December 29, 2009, 5:17pm

So, does it mean that you are able to control the pins with the virtual MIDI keyboard of MIOS Studio as well?

No that function doesn’t work I’m afraid.

With the interconnection test, do you always read 5V on the selected pin, and 0V on all other pins? This would help to exclude a short.

Yes.

LeTran · December 29, 2009, 6:39pm

I’ve attached a picture of just J2-2 connected. As you can see, the LED is lit.

Not sure what to do now really. I’ve tried 2 YMF chips.

Shuriken · December 29, 2009, 9:16pm

I’ve attached a picture of just J2-2 connected. As you can see, the LED is lit.

Not sure what to do now really. I’ve tried 2 YMF chips.

I seem to have noticed this behaviour with my mbfm aswell. Which seemed kinda odd to me.

I don’t have any problems though.

LeTran · December 30, 2009, 10:38am

I’ve just been checking the parts over.

I’m using TL074CN op amps - are these OK ?

Shuriken · December 30, 2009, 3:54pm

I’ve just been checking the parts over.

I’m using TL074CN op amps - are these OK ?

Yes, i used the same.

But i was looking at your picture. And it seems to me that the polarity of C16 is wrong. Uh nevermind…it seems mine is wrong :pinch: .

Maybe you could post some detailed pictures of top and bottom of the pcb?