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Midibox CV - Aout_NG Problem

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I've just finished building my Midibox CV using the NG module. The software seems to have loaded ok, and I can use the LCD screen etc. but I don't seem to be getting the correct voltages at the CV outputs.

In the calibration menu, no matter if its set to 'Min' Max' '1.00v' 2.00v' etc. the CV outputs stay at 0.01v and turning the trimmer on the NG board does nothing.

The only thing I'm doing differently to the instructions is the grounding. I've connected one output jack to ground on the PCB and then daisychained the rest of the jacks to that connected jack. Do you think this might the problem?

All the solder connections appear to be ok.

Any help would be much appreciated!

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It shouldn't matter how you ground things, as long as there's only ONE ground and that's going everywhere you need it. Are you using the bipolar option? What PSU are you using? An shorts/bridges on the AOUT_NG? Got some high-res pics?

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It shouldn't matter how you ground things, as long as there's only ONE ground and that's going everywhere you need it. Are you using the bipolar option? What PSU are you using? An shorts/bridges on the AOUT_NG? Got some high-res pics?

Thanks for the reply!

Just to give you some background:

I'm using the Midibox CV as a convertor inside my DIY modular. I have the eight CV outputs from the AOUT_NG as well as the 8 Gate outputs, the Clock Out and the Start/Stop from the CORE module on a front panel. The CORE PCB is powered by its onboard power supply, the AOUT_NG is powered by the +/-15v supply inside my modular.

The CV output jacks are daisy chained together and then grounded at one point (J5) on the AOUT_NG PCB. The 8 Gate outputs come from J5 on the CORE module and are grounded to the ground on that PCB.

I'm not using the bipolar option.

Both TL072 sockets measured the correct voltages at the correct pins.

I can't see any shorts or bridges on the AOUT_NG and I'll try to get some high res pictures up tomorrow morning.

One thing I'm not sure about is the TLV5630. I was going to buy from RS but they were sold out at the time so I bought a couple from eBay for much cheaper. I'm a little concerned that the TLV5630 might be a dodgy one -is there anyway to check?

Thanks!

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hi LB,

i do the same. but i am using mbseq.

+/-15v is no prob.

there was another post with similar symptoms to you.

they hadnt connected ground at the modular pwr connector.

see here:

so it all depends... but try that first.

like nILS said you need just one ground going everywhere its needed.

just had a look at mine and i've disconnected it.. strange & i dont remember why.

my aout_ng is connected to ground via core.

my jacks are daisychained just like yours.

seppoman may have info on testing the DAC.

and how are you powering your core?

good luck. gotta be something simple.

Thanks for the reply!

Just to give you some background:

I'm using the Midibox CV as a convertor inside my DIY modular. I have the eight CV outputs from the AOUT_NG as well as the 8 Gate outputs, the Clock Out and the Start/Stop from the CORE module on a front panel. The CORE PCB is powered by its onboard power supply, the AOUT_NG is powered by the +/-15v supply inside my modular.

The CV output jacks are daisy chained together and then grounded at one point (J5) on the AOUT_NG PCB. The 8 Gate outputs come from J5 on the CORE module and are grounded to the ground on that PCB.

I'm not using the bipolar option.

Both TL072 sockets measured the correct voltages at the correct pins.

I can't see any shorts or bridges on the AOUT_NG and I'll try to get some high res pictures up tomorrow morning.

One thing I'm not sure about is the TLV5630. I was going to buy from RS but they were sold out at the time so I bought a couple from eBay for much cheaper. I'm a little concerned that the TLV5630 might be a dodgy one -is there anyway to check?

Thanks!

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Hey SMIDIRIN!

I'm powering my CORE by feeding the onboard power supply with 12VAC from a transformer - this is separate from the power supply that feeds the rest of the modular.

You both say I should only have one ground but there are two, aren't there? The digital ground (DGND on the AOUT_NG schematic) from the CORE and the analogue ground (AGND on the AOUT_NG schematic) which comes from the +/-15v power supply. On the front panel, where the signal is coming from the CORE (i.e. a gate), I have connected the jack to the CORE's ground (DGND), and when it's coming from the AOUT_NG (i.e. a CV signal) I have connected it to the analogue ground (AGND). Is that correct?

Thanks a lot!

hi LB,

i do the same. but i am using mbseq.

+/-15v is no prob.

there was another post with similar symptoms to you.

they hadnt connected ground at the modular pwr connector.

see here:

so it all depends... but try that first.

like nILS said you need just one ground going everywhere its needed.

just had a look at mine and i've disconnected it.. strange & i dont remember why.

my aout_ng is connected to ground via core.

my jacks are daisychained just like yours.

seppoman may have info on testing the DAC.

and how are you powering your core?

good luck. gotta be something simple.

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:wacko: as the expansion continues it becomes even more complex.

wait and check with other users for more hints, but my system is like this:

i've just continuity checked and both grounds are connected on mine.. and it's gotta be the alum. frontplates and jacks, it's also then connected across 3 separate metal racks via patch & midi leads..

it has been a while but i did have all kinds of prob when i upgraded my psu(s) and added more modules.. dunno if that helped (but maybe?) :unsure:

i'm 100% diy and i just do what works so you might need some other advice! :D

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The analog and digital grounds are connected on the AOUT_NG modules. There can only be one ground. If you have more, how on earth would the voltages be referenced towards each other?

Without having seen some pics of the board and your wiring it's really kinda hard to give you any further hints - make sure you have the wiring correct (between core and aout) and you've jumpered the AOUT_NG board correctly. Check if all the parts are correct, report back :)

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Sorry yes you're right - there is only one ground. I've checked and there is continuity between the AGND on the AOUT_NG module and the DGND on the Core module.

The wiring between the CORE and the AOUT_NG appears to be ok, as does the jumpering.

Here are a few pictures...

The analog and digital grounds are connected on the AOUT_NG modules. There can only be one ground. If you have more, how on earth would the voltages be referenced towards each other?

Without having seen some pics of the board and your wiring it's really kinda hard to give you any further hints - make sure you have the wiring correct (between core and aout) and you've jumpered the AOUT_NG board correctly. Check if all the parts are correct, report back :)

post-6688-086500600 1296211816_thumb.jpg

post-6688-049676100 1296211963_thumb.jpg

post-6688-069993900 1296211991_thumb.jpg

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hi again. :smile:

ok. question time..

your soldering on TLV is fine i think but did you test with multimeter ?

are the opamps in their sockets properly ?

did mios and mbcv app upload correctly ?

is your led lit ?

connected to core as shown in this file: mbcv_aout_ng_interconnections.pdf ? (link dead!)

have you checked #define DEFAULT_AOUT_INTERFACE 3 (and recompiled) ?

do you get gate(s) on note-on(s) ?

have you set MIDI EVENT to NOTE ?

do you see meters move per channel when sending midi ?

have you checked all 8 cv channels for voltage change ? (maybe some are working)

has it magically started working ? (it happens..)

also i think you should connect all your jacks grounds together and then make one connection back to core OR aout_ng..

i kinda remember having a similar problem and thought i had fried my DAC but it was fine.

my problem ended up being my jacks were all connected but not connected to my midibox ground. duhh! :pinch:

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have you checked #define DEFAULT_AOUT_INTERFACE 3 (and recompiled) ?

Ooh, that is a good point!

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Ooh, that is a good point!

Haha! That was a very good point! I had forgotten to do that so I recompiled and... voila!

Thanks both of you for your help - it's much appreciated!

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Haha! That was a very good point! I had forgotten to do that so I recompiled and... voila!

Thanks both of you for your help - it's much appreciated!

have fun.. :thumbsup:

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