e-licktronic Forum

I've created this thread to document any issues I've had with my build and how they were rectified in an effort to help others in the future who may stumble across the same issues.

I would consider myself a reasonable DIYer. I've done a lot of soldering and have been building tube microphones (from schematics, not kits) for a couple of years now and I've put together a stereo VCA compressor with minimal issues but the sheer number of components in this project means it's very easy to slip up.

When building this I took my time and checked each component carefully ensuring the correct component (multi on all resistors) was selected and that it was in the correct orientation. I did make a silly mistake while rushing the sequencer section as documented below but this was because I've socketed all of my ICs and thus I can no longer easily see the silk screen showing the IC's orientation. I've since gone over the whole PCB and all other ICs are in the correct orientation.


--=={Unsolved Issues]==--

[ISSUE - NOISE MEASUREMENT]
With a 4K7 resistor at R127 I still didn't have 130mV in the noise section and the snare sounded weak. I've replaced it with 1K and I could get up to 110mV. It's a bit snappier now but I'd like to go a bit further. I'm not sure if reducing R127 more is a bad idea though.

Any thoughts?

[ISSUE - KICK DECAY]

My kick will self oscillate if I turn the davy up to about 75%. I also have kick decay adjustable from zero to self oscillation. Not a huge issue because I actually love it but I'm not sure what the cause might be.

--==[Solved Issues]==--

[ISSUE - SEQUENCER]
My sequencer is massively wacky. It won't play, no matter what I do. The mute LED is always on in pattern mode and the shift button changes the scale led lights. Some of the patter buttons aren't working and they often make other LEDs light up at random.

Now...

I took so much care while building this initially. Double and triple checked every component. Even checked every single resistor with my multi just to be safe. But in my haste at 11:30PM after 5 hours of building in a rush to get it done before bed I had IC8 (74hc165) in backwards!!!!! OH NO!!!!!

Now this was easy to rectify because I've socketed all of my IC chips but I'm pretty sure I've fried it because switching it with IC7 created entirely different but not much more useful behaviour. At least all of the pattern buttons work now without turning each other on. I've also noticed that removing IC7 altogether (previously IC2, the one which was in backwards) doesn't seem to affect its behaviour at all.

I've tried reloading the firmware over MIDI which appeared to be successful but no luck.

Does this sound like a dead chip?

[SOLUTION]
I've replaced the the ICs with these bad boys I picked up from Jaycar http://www.jaycar.com.au/productView.asp?ID=ZC4858. After I initialised and the sequencer now seems to work fine.

[ISSUE - SOME VOICES NOT WORKING
R151 has burned and the only sound I'm getting is closed hi hats. I've checked 4011, C34 and Q27 as per a suggestion in another thread and they're both the correct part and in the correct orientation.

I'm also listening through headphones and the volume is super quiet. I can barely hear the hats with all volumes cranked.

(More details on this issue in the posts below)

[SOLUTION]
Replaced 4011 IC. Instantly solved the issue.

Cleaned up the thread, changed the title and added my latest issue.

I've had a poke around and the only solder bridge I could find was between pin 14 of the 4011 and R102 which shouldn't matter anyway because they're both be connected to +15V on the schematic. I've looked with a magnifying glass and there's definitely no other solder bridges

I'll keep looking...

I've replaced R151 with a higher wattage resistor. It's discoloured after testing for about 15 minutes so there's definitely still an issue there but I've been over the accent section and I can't find any errors

The weird thing is my cowbell, cymbal open hi hat and closed hi hat are all working but no other sounds are working.

In addition, if I turn up the bass drum decay all the way there a bass oscillation that sounds like it's feeding back. It gets gradually louder until it it starts clipping and won't stop until I turn the decay down. It does this regardless of whether is playing or not.

Any ideas for things I can check???

More observations:

Toms and congas are kind of working but are very quiet compared to the maracas, hats, cymbal and cowbell.

Bass drum still has the previously mentioned issues but it and the snare will play extremely quiet sounds (snare has no snappy and bass drum has no decay). When the accent is turned up there is no sound from kick, snare, toms, clave or maracas. Cowbell, cymbal open and closed hats are not affected by accent in any way, even programming accent notes has no effect.

To make things even more strange if I unplug it from the AC then plug it in and press play very quickly it will play a perfect bass drum, then go back to very quiet. For a while the snare was producing a little noise on the first snare played but not any subsequent snares but now the noise is doing nothing. I originally was able to get 130mV in the noise section but now I can't no matter what I value resistor I have at R127. I've tried 47K, 4K7, 2K2, 1K and even a 0ohm wire and can't get 130mV. Votages are all OK, none of my +B from the schematic have continuity with ground.

Claves and will only work if I program at least two consecutive notes and even then it doesn't play the first note for some reason. No sound at all from rim shot or hand clap.

So it seems my noise isn't working and there's still an issue with the accent. Been through everything and can't locate.

I'm almost at the point we're I'm prepared to de-solder every component and source replacements for everything. After hours of searching I can't find any faults anywhere in the circuit

Dear Krisbo,

Some diyer get the same R151 problem.
Try to replace the 4011 in the accent section.
It's not a good idea to replace R151 with higher wattage because this resistor protect the accent circuit.

I think a lot of your problem depends on the accent issue

Best regards,
e-licktronic

I'll order one and give it a go.

When I say higher wattage, I've replaced it with 1/2 Watt as opposed to 1/4 Watt so not a massive increase.

Replaced the 4011 with a 4011BE I picked up from Jaycar and away it went! Thanks for the tip .

With a 4K7 resistor at R127 I still didn't have 130mV in the noise section and the snare sounded weak. I've replaced it with 1K and I could get up to 110mV. It's a bit snappier now but I'd like to go a bit further. I'm not sure if reducing R127 more is a bad idea though.

Any thoughts?

krisbo wrote:Replaced the 4011 with a 4011BE I picked up from Jaycar and away it went! Thanks for the tip .

With a 4K7 resistor at R127 I still didn't have 130mV in the noise section and the snare sounded weak. I've replaced it with 1K and I could get up to 110mV. It's a bit snappier now but I'd like to go a bit further. I'm not sure if reducing R127 more is a bad idea though.

Any thoughts?

Just a thought, I couldn't get below 250mV, and then I realized C106 was 0.47/50 instead of 47/16. It solved the issue.

They are in the same bag, and you get a dozen out at the beginning of the built. ... check all of them

Hi,

I've got the same problem i think,

My open hat didn't work at a moment, the cowbell and the cymbal neither.
But the closed hat works.
So should it comes from the accent, or the trigger i think, where to look please?

What is more weird is that before, when my hats were working, the maracas was very quiet, but now, the op hat doesn't work and the maracas has more volume, normal volume.

so weird , where should i watch?
thanks


SOLVED: OK mea culpa , it was the ribbon cable!!!

So now, my little problem is that the CY and the Cow bell don't go enough high in frquency , what to change please?