Troubleshooting

[netpusher]

Adding a section for troubleshooting issues on the CB55.

[netpusher]

Having issues getting any sound on my CB55, it's probably something simple, but I can't seem to figure it out.  Here is what I have for my setup:

Standard 12v benchtop power supply on the +12 and GND.
Alpha A10k - volume pot
Alpha B1M - tone pot
Alpha B500k - accent pot

For my trigger source:
TipTop Audio Circadian Rhythm

Just to get the ball rolling, I am posting an image of voltages on the board I probed tonight.  
The Yellow dots are 6.15v and the Pinkish ones are 8.91v

Also, I am using TRIG_IN1 attempting to get a sound from the HiHat since I can see voltage getting to that section it seems.

[Circuitbenders]

Obvious things first: have you got all the diodes, transistors or polarised caps the right way round? You might think you have, but check anyway.

Those power readings look fine.

Have you tried a different LM324? What transistors are you using? Are you sure they have the same pinout as 2SC945's?

Have you got the jumpers for the individual outputs soldered in place? I once spent a couple of days exchanging emails with someone who couldn't get any sound out of there CB55, before they remembered that they were going to install individual outputs and so they hadn't soldered the output jumpers in.

Assuming you have the jumpers installed, try connecting the tip of an output jack to any jumper from J3 to J7, and triggering the sounds. The jack sleeve should be connected to the common ground. This is the mix bus before the output stage , so it should tell you if the sounds are working but the output and tone circuit isn't.

You really need a scope to be sure if the triggering circuit is working properly. Dies the Circadian Rhythm output 5v pulses?

[Circuitbenders]

This is some additional advice from a couple of messages exchanged with netpusher.
I'll post it here in case someone find it useful


What you could try is triggering the sounds with the 6v from the DR55 board itself. Just above where it says C4 near the 6v regulator theres a hole through the board. There should be 6v here, so if you short it to a trigger input it should trigger the sounds if they are working.

You could also try the trigger inputs at the TRIG2 connector. If they work from here then your LM324 is probably dead or theres something weird happening with your 9v supply

Connect an output to the left hand solder pad of J5 with no wire jumper in place. Make sure you have the ground of the output connected to the circuit ground.
If you short 6v to pin one of the TRIG1 input it should trigger the rimshot, if this doesn't work try shorting 6v to the middle pin of the TRIG2 input.

If you still get no sound triggering the rimshot from the TRIG2 input, then i'd start to suspect something other than the CB55 board. Theres only about 17 parts in the rimshot. If you have power, the diode is the right way round and the transistor is a 945 or equivelent, then theres really not much that can go wrong!

[netpusher]

Thanks for all the help on troubleshooting this with me!  It turned out to be 3 non 1N4148 diodes I got mixed up and wound up on my board, I really should have seen that one! 

[Circuitbenders]

Thats a good looking case. Is the lettering letraset or something?

Why do you have an output for the accent?

[netpusher]

It's a front panel express job.  That accent out was a copy/paste mistake I made on the design, didn't realize I had done it until after it went to manufacture.  Oh well.

[gert]

nice case, i also wanted to order at "schäffer" but the exploding costs always kept me back.

accent, i could not find any musical use for it since it affects all volumes, so i do not trigger it at all (sequencing with mtrx-s jam machine, only preset patterns...). but with the accent trimmer you can push the bassdrum into ranges as if accent was on all the time - even if it is not triggered. its like a nice preamp that can give some crispy overdrive to all sounds, it makes intense sounds and does not clip the inputs on my mixer.

[witchfinder]

Hi!

Finally I had all the parts together to build my CB55, and after adjusting the noise everything worked fine except the Hi-Hat!
When I trigger it via the TRIG IN1 I don't get any sound at all, and via TRIG IN2 there's a constant noise over the Hat.

So I guess it has something to do with the conditioning circuit, but I have no clue what it might be. I've already checked my soldering and every diode concerning the Hat circuit.

Maybe somebody has an idea.

[Circuitbenders]

What are you using for triggers, and what does 'a constant noise over the Hat' mean?

[witchfinder]

I create my trigger pulses with a µC (XMC) since it's intended to be kind of a studying project haha
Those pulses seem to be fine, even if I make them longer the conditioning circuit cuts them to the right length.

There's a constant buzzing sound when I trigger the Hat via TRIG_IN2, additional to a small clicking sound.
When I trigger the other three sounds via TRIG_IN2 it works fine.

So my guess was that there is some noise coming from the conditioning circuit, is it possible that my LM324 is partly broke? I don't have a second one right now, so I can't check that.

[CeeFo]

Would a 5 volt regulator work in place of the 6v REG 1?

[Circuitbenders]

CeeFo - A 5v regulator would work, but its probably not going to sound quite right.

Witchfinder - I'm assuming that if you know tjat the conditioning circuit is giving you the right length triggers, then you've looked at them on a scope? If so, what are you actually seeing for the hat trigger at TRIG_IN2, when you trigger it from TRIG_IN1

The the noise for the top end of the snare working properly?

It seems unlikely that the LM324 might be damaged, but i guess its possible. Have you checked D4?
If the trigger and noise part of the snare are ok., then i'd probably be looking at the transistors in the hat at T6 and T7, unless you have something shorted somewhere

[inf23]

hi there,

finished my build yesterday, so far everything works ok apart from:

no hihat sound
the snare just "plops" like a tom

so it seems the noise circuit is not really working, i checked all the caps and diodes for correct orientation, so far everything seems to be fine...
can you give me any advice regarding which voltages i should be able to measure on various parts of the board so i could check what is responsible for the non-working noise circuit?

regards

[Circuitbenders]

inf23 - possibly an obvious question, but i assume you've adjusted the noise pot at VR2?

Theres only 9 components in the noise circuit. If both the hats and the snare noise aren't working, then you'd have to assume its one of them. You could try probing with an audio jack around the c25 side of R57, and the C32 side of R69. I think you should be hearing noise at both of these points if the noise circuit is working.
You might have dodgy transistors at T4 or T5, but if all of the components are correct then theres not really much that can go wrong.