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Mutable Module Tester
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2 [all]
Author Mutable Module Tester
Neutron7
the 25mm encoder is out of stock at mouser canada but they have 30mm version here i imagine it can be cut if neccesary, or just use a different knob.

http://ca.mouser.com/ProductDetail/Bourns/PEC12R-4230F-S0024/?qs=sGAEp iMZZMsWp46O%252bq11WUFm4YUtE9euoOtONkFJIaM%3d
gerard
Hello,

I have built the module tester. However the display’s first line all the pixels are lit. Turning the encoder some times they all go out. The switches and leds all function. The voltages are all good at the power header. I get sine, triangle square etc out of the audio out jack. I have moved the contrast pot does not make a difference.



I have ordered another pre programed chip from Thonk, however since I get waves out of the audio jack out I suspect the chip is probably working. I have reflowed the display solder connections and checked for shorts and continuity back to the main chip every thing looks ok.


Any ideas what might be wrong?
AndrewHP
It's possibly something simple like the contrast being wrong - there is a trimmer near to the display - have you set that?

Edit -----

I see that you said you set the contrast. What display did you use, and what resistor did you put in the one near the trimmer? Maybe that is a factor. I think I read someone say to use 68r if you're unsure and work from there - it seemed to work fine for me so I stuck with it.

If you have the part number of your display someone more knowledgeable than me should be able tell you the right one.
gerard
Yes, I have adjusted the contrast, makes no difference all the pixels are on. Set at a good level I get about .7volts on the display pin for contrast.
puzo
Rather than start a new thread, thought I’d post here.

How long should it take to calibrate the module tester. Following procedure but just can’t seem to get the 3v near 3v. If the 1v is bang on 1v the 3v is approx 3.15v and can’t seem to get any closer. Trimming down the 3v lowers the 1v and viseversa

Any help or advice would be greatly appreciated, thanks
DMR
puzo wrote:
Rather than start a new thread, thought I’d post here.

How long should it take to calibrate the module tester. Following procedure but just can’t seem to get the 3v near 3v. If the 1v is bang on 1v the 3v is approx 3.15v and can’t seem to get any closer. Trimming down the 3v lowers the 1v and viseversa

Any help or advice would be greatly appreciated, thanks


Are you using both trimmers? One should be offset and one should be scale. First using the scale trimpot to scale the voltages to be 2v apart (no matter whether they are 1v and 3v, 1.2 and 3.2, etc. Then, using the offset trim to move them to the correct 1v and 3v.
puzo
Thanks dmr, will adjust, measure and report back
puzo
hi DMR

the best i can seem to get it 1v 3.035v, what do you think?
DMR
puzo wrote:
hi DMR

the best i can seem to get it 1v 3.035v, what do you think?


The circuit for the CV output is on the 3rd page of the schematic (https://mutable-instruments.net/archive/schematics/Module-Tester-v01. pdf) in section A3 and A4. I would check the color codes of resistors R12, R6, and R10, to be sure they're correct, and that the reference voltage from the LM4040 is correct.

Of course the module tester is also still usable overall with 1v and 3v at the output, it just makes it less useful for calibrating the CV input of other modules.
synthetek
puzo wrote:
hi DMR

the best i can seem to get it 1v 3.035v, what do you think?



What kind of meter are you using?
puzo
will double check all recommendations. The dmm is an extech EX430A
puzo
the resistors are fine, not getting anything from the lm4040 that makes sense to me, bit of a noob. gnd leg 3 right of flat side, ref volt out leg 2 in the middle? getting fluctuating mv not the -4
eewee
a quick word of thanks for all the shared information in this and related threads.

I just built my tester from a PCB bought at Thonk (not my first DIY project, but the first one where I sourced all the parts myself - hooked now!). Reading this forum (and the MI one) was invaluable to avoid silly mistakes and hours of head scratching.

For those that come after me, a few things I learned while building (I had the casing from the GitHub project lasercut):
- the 10mm MF standoffs above the PCB are indeed too short (can't fit the vertical trimmers) - you need something like 11mm;
- you can add spacers/washers to get to the desired height, but be smarter than me, and add those spacers at the bottom end of the standoffs (near the PCB), rather than at the top end (where they'll fall out every time you undo the top panel screws);
- having a clear plexiglas case forces you to clean off flux traces from the PCB - this is the cleanest build I have ever done :-)

This has been a very enjoyable build, with stuff I learned ranging widely from mechanical stuff to MCU programming.

Big thanks to Olivier for this project and everybody who contributed to it.
c0ntr4d1ct10n
I broke the 24 ppr 24 detent encoder that I bought from mouser (damn pcb board that I got from Found Sound in Melbourne didn't have holes wide enough for the snaps on the side and it must've detached something inside because it felt very loose. When I tried it, it wouldn't do anything. So I replaced it with a 20 detent encoder that I had on hand (there are no 24 ppr rotary encoders in any of the stores where I live). The encoder sort of works, but doesn't really respond to turning it.

Does anyone know if it is just a matter of changing some lines in the firmware code to suit this encoder or would I have to find a 24 ppr one?
Altitude909
c0ntr4d1ct10n wrote:
I broke the 24 ppr 24 detent encoder that I bought from mouser (damn pcb board that I got from Found Sound in Melbourne didn't have holes wide enough for the snaps on the side and it must've detached something inside because it felt very loose. When I tried it, it wouldn't do anything. So I replaced it with a 20 detent encoder that I had on hand (there are no 24 ppr rotary encoders in any of the stores where I live). The encoder sort of works, but doesn't really respond to turning it.

Does anyone know if it is just a matter of changing some lines in the firmware code to suit this encoder or would I have to find a 24 ppr one?


It makes no difference, its used only to increment or decrement values, PPR is irrelevant here. U can use 10 if you want
c0ntr4d1ct10n
Altitude909 wrote:
c0ntr4d1ct10n wrote:
I broke the 24 ppr 24 detent encoder that I bought from mouser (damn pcb board that I got from Found Sound in Melbourne didn't have holes wide enough for the snaps on the side and it must've detached something inside because it felt very loose. When I tried it, it wouldn't do anything. So I replaced it with a 20 detent encoder that I had on hand (there are no 24 ppr rotary encoders in any of the stores where I live). The encoder sort of works, but doesn't really respond to turning it.

Does anyone know if it is just a matter of changing some lines in the firmware code to suit this encoder or would I have to find a 24 ppr one?


It makes no difference, its used only to increment or decrement values, PPR is irrelevant here. U can use 10 if you want


Okay, so it must be due to another issue? The encoder I'm using doesn't respond well to turning it. i.e. when I turn it most of the time nothing happens but then sometimes it changes the value. Clicking it works without any issues.
Altitude909
its either a bad solder joint on the encoder or the uC, there is nothing else in between
c0ntr4d1ct10n
Altitude909 wrote:
its either a bad solder joint on the encoder or the uC, there is nothing else in between


Turns out I didn't set the fuses.

Anyway, now I have another problem. The circuit was mostly working with DC supply (except for a number of audio jacks which had bad solder joints). I then found out that I should be using AC supply. So I bought a 12VAC 1A wall wart and it was still working the same when I plugged it in. It was even still working after a few minutes when the 4700uf cap started smoking and leaking. When I removed the cap and investigated, I found out that there was a short between the +12V pin and ground pin of the 2.1mm power connector, but only when I plug in the adapter, without powering it on.
Altitude909
u probably had the cap in backwards
flts
c0ntr4d1ct10n wrote:
I found out that there was a short between the +12V pin and ground pin of the 2.1mm power connector, but only when I plug in the adapter, without powering it on.


How many ohms does your multimeter still consider a "short" - can you measure the actual resistance between the +12V and 0V? Usually the meter beeps in continuity mode with lower than "a couple of ohms" of resistance, and that's something that's expected.

It sounds probable that the cap was backwards as Altitude says, and the low resistance between power rail and zero volts is expected due to the transformer / power supply design.
c0ntr4d1ct10n
flts wrote:
c0ntr4d1ct10n wrote:
I found out that there was a short between the +12V pin and ground pin of the 2.1mm power connector, but only when I plug in the adapter, without powering it on.


How many ohms does your multimeter still consider a "short" - can you measure the actual resistance between the +12V and 0V? Usually the meter beeps in continuity mode with lower than "a couple of ohms" of resistance, and that's something that's expected.

It sounds probable that the cap was backwards as Altitude says, and the low resistance between power rail and zero volts is expected due to the transformer / power supply design.


Yes, after buying a second 12VAC adapter and some new caps, I realised when I replaced the 4700uf that I had it on backwards (ლ‸-)(-‸ლ) - rookie error - first time this has happened. Also learnt after finding a datasheet on mouser of what it looks like inside an AC adapter that it is just a transformer and of course it is connected from power to ground.

Also since I may have bought the wrong series of pj301bm jacks from thonk, the legs didn't fit inside of the holes of the pcb (or maybe the pcb wasnt drille correctly in manufacturing) so I had to trim the legs and surface mount solder them onto the pads - which is quite difficult to do with the plastic of the jacks in the way.

I finally managed to get it working properly now.
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