Another Programmer debugging thread

Hi guys,

I just assembled my programmer board this morning but when I turn the Shruthi on, I get a slightly lit blue screen instead of the normal splash screen.

The led on the board is also barely lit…

Does that sound familliar to you ? (i can provide pictures if necessary)

Update : after checking for shorts, it turned out it was coming from port 2 : I don’t know how but some residual solder was stuck between the IC and its socket…

The good neews is that now it is working ! Or rather it is close to be working… There are a few issues like one or two pots modifying two parameters at a time while a few are not responding so I need to see where I messed up with cables…

Something else bothers me on a higher level though : most of the time, minimum value is around 20 and not zero when I turn knobs all the way left…

Also, a few of them are “hard” to turn…

Is there any way I can fix that ?

Perhaps your PSU isn’t powerful enough?

Either that or there’s a slight short or other problem?

Or you shorted something somewhere…

Were you wearing shorts at the time? :wink:


If the pots don’t work 100% or change 2 Values at a time theres somewhere a Bridge/Short.

If the pots are hard to turn most likely the Knob touches the Panel, so lift it up a bit. The feel gets a bit softer when turn a few hundred times :wink:


When you say “don’t work 100%” you’re referring to this “minimum value” issue right ?

I’ll try to lift up the hard ones a bit then…

I’ve sorted out a few things but I still got that “minimal value” thing going on, it’s affecting all parameters : I can go below /- 25 out of 127 and/- out of 64 (approximately) or for example when selecting waveforms I can’t access the first 10.

There must be something wrong somewhere but I can’t tell what…and it’s killing me :slight_smile:

Any ideas ? Maybe one connection in particular I should have a look at provided this symptom ?

So this affects all Pots which are otherwise working fine? Or are there some that don’t work? If so theres the Spot to start…

Yeah I’ve ruled out other problems and yeah I’m pretty sure it affects every pots…


I’ll check again tomorrow if all parameters are indeed affected but I must say I was hoping you had any idea about where this massively frustrating problem might come from… Damnit I was so close to having my first DIY project finished (wait I still need to add the polivoks Filter…) :slight_smile:

Please take the following measurements: Turn all knobs to the leftmost position and measure the CV Line - it should be 0. If not Disconnect the Programmer and Ground the CV1in line while the Programmer is running. At least then all Parameters should fall to 0 instead of float?

Yeah I’ve got 0 for every pot.

So if you turn all to 0 then all read ? Then somewhere a bit of voltage leaks into the CV Line, try finding the one Pot that causes the trouble by turning one by one…

Could it be that one of the 4051 is not correctly desactivated? So two 4051s are active at the same time and the voltages from the pots are added up?

Good point pichenettes!

Check at every 4051 if its either nicely 0V or 5V.

I’m confused. How can I identify the troublemaker since all of them display 0v when turned left ?

Ok I’ll check for 4051s

I have 5.06v at every IC…

Which pin of the 4051 did you check?