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Turing Machine Pulses Mk ii expander
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Author Turing Machine Pulses Mk ii expander
Thomedwards
So I just finished the Pulses Mk ii expander for the RL. For some reason, it never hits Step 7. Any hints or suggestions?

I'm sure I have missed something, but I'm not sure where to look. Like, which resistors, IC pins, etc, are in Step 7's path. I can't seem to find a schematic. (Maybe my searching sucks.)

Anyway, any and all help is appreciated.
geecen
Do you get no pulse, no led or both? That's probably the first thing to check.

There should be a schematic on the music thing modular website or on the github. Sometimes the schematics are in eagle format though so you might have to download the free demo of that.
heapish
There is barely anything on there....
So my suggestion is, re-flow all your joints and check that the LED is the right way round.
Like geecen said, is it just the LED or do you get a pulse?
drip.feed
Also check your ribbon cable isn't letting you down.
Thomedwards
Both the 7 jack and LED are non responsive. Also, the 4-7 and 1-2-4-7 AND jacks and LEDs are non responsive. Those AND jacks/LEDs not working make me confident that a signal is not making it to the 7.

I haven't had a chance to check out any schematics other than the PDF on the site. I'm curious to know if the LED or the jack comes first in the signal. I'm sure the LED is in correctly, but I'll double check.

This was my first foray into SMD, so I'm pretty sure it's my mistake in that soldering process. I was just hoping I could be a little more focused in my search for the mistake.

Didn't think to check cables. I will definitely check that. Maybe it's not my mistake after all!

I appreciate everyone's help. I'm having an unbelievably good time with this DIY slant on modular, and am learning a great deal. Feel free and encouraged to add more suggestions if you think of anything else.

EDIT: Didn't mention the 4-7 AND not working
heapish
Just thought....cant remember what the back of the main module is like on the mark2 but I remember putting the expansion cable on the mark1 wrong cus it says red at both side of one connection
Sammus
Could be an IC pin. I had this exact problem and it turned out I'd lifted one of the pads. I ended up scraping some screen off near the pad to help tracing, and found a near by through hole leg that it was connected to, ran a jumper and fixed!
Thomedwards
Sammus, your problem was with the same jacks? If so, which IC pin was the culprit?
sempervirent
If I remember correctly, the IC for Pulses v2 is available in two slightly different packages with slightly different part numbers. Are you building from a kit or from a self-sourced BOM?
Thomedwards
Kit.
woodster
High Res pictures ?
Thomedwards
i finally got back to this project and discovered it was what I guess was a lifted pad.

Here are the steps I took to figure it out. I went to GitHub and grabbed the schematic and learned which pin OUT 7 was. Then I ran some alligator clips to see if I could get a pulse if I ran straight to the resistor from the pin. Once I saw that worked, I soldered a wire from the solder side of the pin to the resistor. Then I did a celebratory dance!

A big thanks to you guys for the tips.
lotek
I finished building my Turing Machine mk2, Pulses Expander and Volts. Turing Machine itself seems to be working just fine. Pulses mk2 seems to have an issue with output 4.

Even with a full pattern write, there is never a signal being outputted from output 4, so that LED doesn't light up either.

I wasn't able to find a schematic for the mk2 pulses anywhere, so I could attempt to trace the issue. I'll also reflow one resistor tomorrow which seemed kind of sketchy. Also take some high rez pics if needed.

Does anyone have the pulses mk2 schematic image. Or should I be installing some circuit building software and tracking down a specific format?

thanks for your help

Lotek
hellcore
lotek wrote:
I finished building my Turing Machine mk2, Pulses Expander and Volts. Turing Machine itself seems to be working just fine. Pulses mk2 seems to have an issue with output 4.

Even with a full pattern write, there is never a signal being outputted from output 4, so that LED doesn't light up either.

I wasn't able to find a schematic for the mk2 pulses anywhere, so I could attempt to trace the issue. I'll also reflow one resistor tomorrow which seemed kind of sketchy. Also take some high rez pics if needed.

Does anyone have the pulses mk2 schematic image. Or should I be installing some circuit building software and tracking down a specific format?

thanks for your help

Lotek


I built the kit this week and had a similar issue, but with the 4+7 output, a quick reflow of the IC fixed it for me.
lotek
Thanks Hellcore,

I'll have time to try that after work today and will report back. I used a 10x magnifier to view the solders up close and there doesn't seem to be any issues with contact.. but I'll try anyways to be sure.

The 4+7 never lights up for me either, due to the fact the 4 isn't working, so it could never be 4 AND 7 active logic state with one of the two never triggering

Lotek
lotek
Hi,

I've been trying to troubleshoot the Pulses MK2 module I built.

It seems like a single output (4) isn't working (and hence making some of the combined logic gates ex: 2+4, 1+2+4+7 not trigger).

Tested it with the turing machine and with the toggle switch, I send a full stream of logical 1's out to the pulses, everything not related to output 4 works fine.

Output 4 LED and trigger signal both missing.

I am starting to think there might be something wrong with the chip. Since I doubt a resistor error would break it like this.

Any suggestions? Here are two up close photos, in case I really did mess something up and didn't notice. (note: I did inspect closely with 10x magnifier to make sure there was solid pad/part contact and no bridges).




thanks for your help,

Lotek
emmaker
Quote:
It seems like a single output (4) isn't working (and hence making some of the combined logic gates ex: 2+4, 1+2+4+7 not trigger).


First get the schematics for the turing machine mkii. Don't know if there are any real schematics for pulses mkii or not. But the original pulses schematic should be good enough. Looks like the main difference is just extra resistors, LED and jack to get the 4/7 output.

Get an ohm meter.

Is the turing machine LED 4 on? If not the problem is probably on the turning machine board. So check that out.

If LED 4 works on the turing machine then unplug the turing machine and pulses from power. Measure the resistance between the turing machine mk ii pulse's header and the pulse's header on the pulses board. If they test open then check the soldering on the headers. If those look good ohm out your cable. If the headers and cable are good just start ohming out your board for bit 4.

Then if all that looks good then check out the pulses circuitry on the turing machine mkii. From looking at the original schematics and the mkii schematics I can't tell if pulse 4 is on AND_2C or AND_1D. So check those out.
lotek
Thanks Emmaker,

When you say Ohm out, do you mean continuity test?

My turing machine seems to be working fine, when I hold the switch to activate every step, I make a nice solid line sequence then hold it there and I can see each sequence work through the pulses LED, and if I hookup those outputs to a drum module TRIG input for example, all of them work except the 4. Which doesn't send a TRIG signal or light up the LED.

So I ruled out the Turing machine, cause I could see it sending steps sequentially through pulses and when it's output 4, it just doesn't do anything, then it moved to 5, 6,7...

But you're right, I could check the turing machine connections to that output header for pulses.

I'll do some poking around. Do you know any way I can test with the multimeter, the chip while it's soldered in place? I've never used the oscilloscope to test an SMT chip on a completed project (mainly on breadboards or cables). Any advice on that, I did look up the data sheet on the chip, I am guessing there's no danger in probing all the logic pins and avoiding Vdd and Vss.

Thanks, haven't had to troubleshoot at a circuit level in years. So this is quite interesting.

EDIT: I was looking more in depth at the chip data sheet and logic and figure that is only used to trigger the 4 additional AND logic ports. I see now, that the issue has to be the direct link from the turing for port 4, since that should be a signal right off the cable connecting it to the module. So the chip is not likely involved in this problem.


Lotek
emmaker
Quote:
When you say Ohm out, do you mean continuity test?


Sorry, yes do a continuity test.

Quote:
Do you know any way I can test with the multimeter, the chip while it's soldered in place?


One thing that you could do is turn the clock down to a real slow rate and then probe the chip with a volt meter. When the bits (pulses) change you should see the voltages go from ground to about +12.

Quote:
I've never used the oscilloscope to test an SMT chip on a completed project (mainly on breadboards or cables). Any advice on that


If you have access to an oscilloscope and know how to use it that would make testing a lot easier. Set the scope vertical up for 5V per div (division) and the horizontal sweep to around 1ms per div. Run the turing machine clock at a slower rate. Then start probing the pulse 4 signal from the turing machine board through to the pulses expander. If you have a 2 channel scope hook one channel up to pulse 4 and leave it there. Use the pulse 4 channel as a reference so you know when it is toggling. Trace the pulse 4 signal through the boards seeing where it goes away. Don't forget to ground the scope probe either.

Good luck.
emmaker
Pav
Apologies for opening an oldish thread but i thought better than opening a completely new one.. appreciate if someone can check my logic.

I need help to identify which pins on the chips provides the inputs and 1+2 pulse out. (assuming it works that way)

I have a working pulses MKII with the exception of (1+2) (1+2 4+7) where there is No pulse or LED.

Kit is from THONK fyi.

Since 1 thru 7 are all fine ..Not likely to be expander from the Turing Machine. Since 4+7 is working, It is more likely that if i fix 1&2 , it will resolve the other.

Step by Step I have already replaced the 1K and 2K resistors relating to (1+2) , the socket pins, and re-flowed all pins on the chip.

Im at the stage where to touch the chip any further without some specifics
is more likely to do more damage.

EDIT - found the chip spec for CD4081 .. had misread 8 for a 6.
i nowexpect pin 3 is most likely 1+2

But i now suspect the chip or the board is faulty.. only so may times I can reflow/
arechfer
My problem is different...i got pulses from 1 to 7 and also work 1+2, but 2+4, 4+7 and 1+2+4+7 doesn't(no led and no sound)...any hint?
Thanks in advance
emmaker
arechfer wrote:
My problem is different...i got pulses from 1 to 7 and also work 1+2, but 2+4, 4+7 and 1+2+4+7 doesn't(no led and no sound)...any hint?
Thanks in advance


What two things are common to what doesn't work.
arechfer
emmaker wrote:
arechfer wrote:
My problem is different...i got pulses from 1 to 7 and also work 1+2, but 2+4, 4+7 and 1+2+4+7 doesn't(no led and no sound)...any hint?
Thanks in advance


What two things are common to what doesn't work.


I don't know...if all individual pulses are ok (from 1-7) seems like the IC pins are ok...I suposse...changed 1k and 2k resistors related to 2+4...to try...and works the same...i think that the polarity of leds are ok also...don't know what else try
Thanks
arechfer
emmaker wrote:
arechfer wrote:
My problem is different...i got pulses from 1 to 7 and also work 1+2, but 2+4, 4+7 and 1+2+4+7 doesn't(no led and no sound)...any hint?
Thanks in advance


What two things are common to what doesn't work.


you mean 4 and 7?
they work alone...but not when they're summed
arechfer
i think i finally fucked up everything...TM included...accidentally connect TM power to pulses and TM pulses to power very frustrating very frustrating
thanks for ur effort
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