Circuitbenders Forum
Circuitbenders Forum => Drum machines => Circuitbending discussion => circuitbenders.co.uk CB55 - DIY Boss DR55. => Topic started by: netpusher on March 18, 2015, 03:57:11 AM
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Adding a section for troubleshooting issues on the CB55.
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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.
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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?
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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!
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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!
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Thats a good looking case. Is the lettering letraset or something?
Why do you have an output for the accent?
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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.
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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.
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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.
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What are you using for triggers, and what does 'a constant noise over the Hat' mean?
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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.
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Would a 5 volt regulator work in place of the 6v REG 1?
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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
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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
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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.
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I've got everything working but the bass drum. Bass drum just makes faint clicking sound when triggered. Component values all double-checked. Any ideas?
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suspect transistors or transistors with a different pionout?
Assuming you're using the trigger conditioning, you could try the trigger from a different channel at the TRIG_IN2 header i.e. try triggering the rimshot at TRIG_IN1 and shorting the conditioned rimshot trigger on the middle pin of TRIG_IN2 to the bass drum on pin 4. If the bassdrum triggers ok then its possibly the bassdrum trigger conditioning thats faulty.
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Good tip. Took your advice and tried the trig 2 route, I notice that when I trigger the rimshot and short it to bass drum trig2 it cuts the rim shot out (mostly). The snare and hats trigger with the rimshot in this fashion but a bit of a short to the bass drum trig2. Hmmm.
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I've been trying to get some sound out of my board for a while now. Today I hooked it up to a scope to see what was going on with the triggers, and it looks like I have nice 12ms triggers coming from Trig_2 when applying 6V on Trig_1. But none of the voices produce any signal, not on the main out, nor on the jumpers. Any ideas?
I used 2SC495s and a J201, and all polar caps and diodes are in the right way.
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That might suggest your 2SC945's ( iassume you mean 2SC945 when you say 2SC495) might have a different pinout for some reason.
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As mentioned in another thread, I did not get 2SC945s but KSC945s (even though they were sold as being 2SC) and after removing all of them and bending the legs everything works but the noise. I'm assuming I fried one or both of the transistors in that part when desoldering or bending them. It'll probably be all good once I replace them.
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Hello,
I finished the soldering of the pcb but I din't have sound with trigger on HH and nothing on master (it's not a problem for the master cos I only want to use individual outs).
So I tried different thinks :
- change transistors T6 and T7
- verify all components values
- change VR2 value (turned it on maximum with snare sound)
But I have nothing on J2 and J4.
I putted an audio jack to listen what happened and there is noise on R70 (next to C35) and I have a bass drum sound (...) on R67 (next to C34).
So I'm disillusioned...
Do you have an idea to resolve these ?
Thank for your help
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I have finished populating my circuit board and have began testing everything, but I get nothing other than a loud buzzing sound. I started off being able to hear the trigger input through connected speakers through both sets of trigger points but after having started checking things, resoldering a few possibly-suspect joints etc that has gone, only the buzzing remains. This gets worse when I touch the volume and tone pots, and some other random bits, such as the bare metal round the lower right hand screw hole. I guess maybe I have 2 problems: the buzzing is a grounding problem, right? And the other being that it's not working.
I'm using a Beatstep Pro to trigger, using a 100k and a 68k resistor in a voltage divider which gives an output of about 4.7V which should be ok?
Got all the components as listed from Tayda, except, I got a J107 JFET as I read "somewhere" it was an acceptable replacement for a J201, the tantanum cap and the 47uH inductor from Farnell.
Using a 12V PSA from a Behringer mixer to power which works ok with the mixer, but I've also used a Boss 9V.
Had a go at testing the voltages at various points with a multimeter, got power going through some and not others so I'm going to map these when I get free time. Funny thing is I'm getting roughly double the voltages that netpusher wrote on his photo on the initial post - just over 12V near C4 and C33 and just over 19V on that leg of the chip and near C2.
Please help! Have I broken/overheated something? Is it my bad soldering? I reeeeally want this to work, it seemed so straight forward from the guide...
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is your behringer power supply 12 AC rather than DC?
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Indeed it was, so that noise is sorted, thank you.
Currently, everything sounds out ok, something has happened with the hats so that the noise pot acts as an overall level to the hihat sound, but this is the biggest problem:
https://youtu.be/O3efE2hnktQ
Not clear from that crap video but as I plug in the instrument circuits that electric gale sound increases so km guessing something earlier in the circuit is making this horrible sound, but I know too little to figure out what :'(
And TRIG2 doesn't work. Maybe it's all related?
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something has happened with the hats so that the noise pot acts as an overall level to the hihat sound,
If i recall correctly the noise level pot will always act as an overall level for the hihat sound, in that the hihats are made from pure noise.
It would probably have been a better idea to use one of the recommended JFET's at Q1. I have no idea how others might work.
If you've had 12v AC connected to ground and +12v instead of DC, then theres a very real possibility that you've fried several transistors and maybe electrolytic caps.
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Ah ok thanks for that.
Providing I can remove them neatly would it feasible to just replace the transistors and polarized components or should I really just start again?
Through the horrible noise it sounds really good! Would live to actually finish this properly
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Hmmm, thats a tricky one. The problem is that you can't really reliably test stuff like diodes and transistors in circuit, although you should be able to use the continuity tester on a multimeter to get an idea if things have gone short.
Electrolytics would have probably just blown up in your face if they were going to go. They might be damaged, but you can probably leave them in for now. I would maybe replace C1 and C3 in the power supply section anyway though
Make sure you're getting a steady +9v and +6v at the outputs of the voltage regulators.
Is that weird noise leaking in when you have the snare outputs on J1 and J3 connected as well as the hat outputs?
I'd be a a little dubious of T4, T5, T7, and T8
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The weird noise is present with every output and seems to increase when more than one output is connected regardless of whether it's being triggered.
Got approx. 9V and 6V at the regulators, just under 12V at C1 and C3. T4 and T5 0V ~2.5V and ~0.5V, T7 and T8 0V ~6V and 0V.
Loads of resistors and caps with no voltage, dunno if it's because of there being no trigger or anything (eg R1-3 and R6-7, C5-6...). Argh. Too many. Going to start again. Was fun making it even if I broke it a bit. Cheers!
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Hello,
I ordered from the bom for Tayda. They were prompt to deliver and the cost was delightful in itself.
I was able to get the noise filter to stop squealing.
I can hear a very faint bass, rim, snare, and hi-hat. Turning up the volume knob increases gain and hum, but the sound remains very weak. I just printed the schematic and I will go over it.
Finally, the snare does not seem to have any "snare noise"; just the pop of the drum. Are there any known reasons for this, considering my hi-hat does have white noise?
Thanks,
Ben
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... my problem is I got 1% resistors and I can't read them... that's what I need to fix