UPDATED Madbean Gravity Wave problems RESOLVED!

[Steve Blackdog]

Hi Folks

I have spent the last few weeks trying to troubleshoot my Gravity Wave vero build.

My problems are manifold 😢

Presently, I have no pulse on my rate led - just on all the time. My voltages to my TL072s and the PT are within the range, but the LM324 is way too high (apart from ground  (0) and VCC(8.7), all the pins are measuring 6v - 7.5v.

The audio is very fuzzy distortion.   I have reflowed all the joints and cleaned between the copper strips, but nothing seems to make and difference.   I attach the schematic and vero layout plus a couple of pics of my board. (You will see I added a link from the earth track to a new track at the bottom of the board)

I have come to the view that stripboard might not be my thing.  Next step is to start again with a fresh board.  Before I take that step, is there any obvious cause of my problems?

Thanks in advance.

All the best

Steve

[Steve Blackdog]

Here's the layout

[Steve Blackdog]

Updated:

After a thorough search for shorts, and ploughing all the gaps between the traces, I have Chorus!

Hurrah!

Everything works now, except I have the motorboating dim pot issue to resolve.

Lesson learnt: I went at it like a hammer and tongs rather than taking my time and ensuring every component was properly soldered before moving to the next.  As a result I ended up with so much solder on the board that the chances of shorting the traces was magnified ten fold.

As the old adage goes: more haste less speed.

[bean]

IIRC someone else had mentioned the DIM control issue on the mbp forum. Try increasing that 8k2. Does it happen as you turn it up?

Anyway, maybe 22k or higher. Or socket that resistor and find the optimal value.

[Steve Blackdog]

Yes, that's exactly the issue with the dim. Turn it up beyond about 5% and it starts to oscillate wildly.  By 30% all you can hear is the thudding.

Good idea to socket the resistor.

Alex's vero layout has changes to deal with the issue, but it's clearly something still causing problems.

If I get a work around, I will report back!

[Steve Blackdog]

So here's the promised update.

I couldn't trace the problem with the dim pot. I got as high as 300k on the swapped 8k2 resistor. The motorboat noise improved, but clearly there was an underlying issue.

After reflowing etc, I am getting nowhere. So I have just pulled all the components and will start again.

I might try the dirtbox sea machine layout for a change!

[Steve Blackdog]

IIRC someone else had mentioned the DIM control issue on the mbp forum. Try increasing that 8k2. Does it happen as you turn it up?

Anyway, maybe 22k or higher. Or socket that resistor and find the optimal value.

Just wanted to report back. I have been on holiday for a week. With fresh eyes, I noticed a component connection error. A few touches of the iron later I have a 100% fully functioning Mad Bean Gravity Wave. With the wiring error resolved all problems disappeared. The Dim pot works perfectly.

I used the tag board layout with no modifications. So for the avoidance of doubt- it works