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Roland SH5 bandpass filter
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Author Roland SH5 bandpass filter
kragg
Hello

I have built a stompbox version of the Roland SH5 bandpass filter.

The assembly went fine, but no sound comes out from the unit cry
I suspect a wrong wiring (as i suck at this, and as [/img]i think i took care to triple check every soldering, i tested every resistor and the diodes before soldering, etc), as the unit was designed to be built for a modular and not as a stompbox.

Would anyone give a look at my wiring schematic, and tell me if it is correct, please ?
The first one is the "offboard/workbench" version, and the second one is the "final" version, using a volume pot and a 3PDT.
(fwiw, at the moment, the daughter board is not installed, i am using a 15V power supply)





Thank you !
ringroad1
Yeah, sorry - this was probably the first layout I ever did so it's a little wonkier than I'd do it now (although it should work)

Looking at again all these years later I realise the placement of C1 and C2 is a bit confusing, this (attached) slightly revised version might help.

If you've got that right, (and your wiring looks alright, as far as I can see) it's worth checking for any unwanted continuity between adjacent tracks, checking that the ICs are getting power on the right pins, making sure your cuts definitely don't conduct, and then try and probe the signal and follow it through the circuit.
kragg
You're the author ? Oh, thank you so much for creating the layout ! thumbs up we're not worthy

The placement of C1 and C2 led me to ask myself a couple questions indeed, but i think that i have got it right cool
I'm glad to read that the wiring seems correct as well.
Thank you also for the updated layout (that's great !) and debugging the tips.

I have made a couple pictures of my build : it doesn't seem to messy as far as i can see, and i don't see any solder gathering adjacent tracks.
I will run an exacto knife between the tracks to be sure.
I am not very good at audio probing, mainly because i'm not very good at reading schematics wink But i will spend some time trying to hear where the sound passes, and where i hear nothing.
How should i check that the ICs are getting power on the right pins ?

(geeky PS : I have the same red & white robot oops )



plushterry
There's a solder blob bridging in top left corner, might be worth a look
kragg
Yes, i noticed this while looking at the zoomed picture : i will get rid of it.
papz
Double check the cut on trace 8 hole 13 as well.
kragg
In A9 (row A hole 9), the hole shouldn't have been there : i fixed that.
I got rid of the blob in the upper left.
(but it didn't change anything)

Between rows J & K, there is a black mark : it is not solder, it is just a pen marking. (Same with the cut on trace 8 hole 13).
Revok
kragg wrote:
How should i check that the ICs are getting power on the right pins ?


Hey Kragg, just use your multimeter on the volts dc setting like you did for the power supply and check pins 4 and 8.

kragg
Ok, i soldered an alligator clip to the red cord of my DMM. I can't guarantee the readings are accurate, but hopefully it can help.

So here are the results (for IC1, the one on the left):
pin4 = -15.13
pin8 = +15.13
kragg
I made new measurements of each IC (with the alligator-clip-repaired DMM, so accuracy is not 100% guaranteed. However, i double-checked, and it gave me each time the same values) :

IC1
pin1 : -0
pin2 : -0
pin3 : -0
pin4 : -15.13
pin5 : +0.68
pin6 : -1.11
pin7 : +11.34
pin8 : +15.13


IC2
pin1 : -13.65
pin2 : +3.25
pin3 : 0
pin4 : -15.13
pin5 : 0
pin6 : 0
pin7 : +2.74
pin8 : +15.13
Revok
Looks good one the power pins. I'd also check ground continuity just to be sure as well. There's a schematic on this page if you don't have one: http://www.cgs.synth.net/modules/cgs30_bpf.html. What kind of signal are you testing it with?
kragg
Thank you for your help, Revok.

Revok wrote:
I'd also check ground continuity just to be sure as well.

I'm not familiar with this : how should i proceed ?
I will google for some tutorials, and do it tomorrow morning, with a fresh brain.


Revok wrote:
What kind of signal are you testing it with?

You mean audio signal ?
The audio signal was a drum computer through a desk's aux.
The electric signal is a Meanwell PD1525 power supply.
Revok
It might just be the photo but the two pots on the north side of the board look like they're wired wrong.

edit: here's a quick explanation on continuity and how to check it.

kragg
Revok wrote:
It might just be the photo but the two pots on the north side of the board look like they're wired wrong.

Thanks. I think it is an error i made on the wiring diagram, but i think i wired them correctly ( = like the layout tells to).


Revok wrote:
edit: here's a quick explanation on continuity and how to check it.

nice, i'll make the test tomorrow morning smile
Revok
kragg wrote:
Thanks. I think it is an error i made on the wiring diagram, but i think i wired them correctly ( = like the layout tells to).

Ah I see now. Yes that looks correct.
wackelpeter
Well i see some more suspect spots on the board, but can aslo be just flux that is reflecting...

To make sure, i have no bridges between traces i scratch with a sharp cutting knife between the traces and brush off the remains with an old tooth brush... Don't press and scratch to hard, just enough to get rid of the flux and solder between the traces.

P.S. also this one solder Point at pin 5 of the one IC Looks a bit suspicious...
From time to time some of the sockets i use don't cover fully in solder and don't connect properly... perhaps the same on your board too...
plushterry
Once you have got the hang of continuity testing, then you can check that no two adjacent strips are conducting (unless they are supposed to be), after that the next step is to print a copy of the schematic and go through it bit by bit, checking against what you have on the stripboard, making sure everything is connected properly, crossing off with pencil as you go. Be very methodical. It's slow going and boring as hell but my money's on either a resistor leg in the wrong hole or a missing cut., You'll almost certainly find it if you have the patience.
ringroad1
Just looked again at your wiring and the photo looks correct, but I'd just say that the frequency pot is specified as a dual 100K linear. It should do some filtering stuff with two separate 100Ks, just not quite as expected.

I'm guessing you've got the 800R-ish resistor on that switch? Are you sure that's working correctly?

Try checking the audio at different points along the circuit with one of these makeshift probes http://www.diystompboxes.com/pedals/debug.html - I'd start by looking at the input and output of every op amp.

Ah, stripboard is the best isn't it?
kragg
ringroad1 wrote:
Just looked again at your wiring and the photo looks correct, but I'd just say that the frequency pot is specified as a dual 100K linear. It should do some filtering stuff with two separate 100Ks, just not quite as expected.

Yes, i am curious to hear how two pots instead of a dual ganged will affect sound, until i receive the dual ganged knob.

Thinking about this a bit more, while painstakingly trying to debug my circuit this afternoon : i was wondering if it would be possible, when using the dual ganged knob, to add an additional potentiometer to modifiy the offset between the two filters : with the dual ganged knob, we would move both filter at once, but the other knob would allow to have more or less "space" between each filter (the potentiometer would further modify the cutoffpoint of one filter).
I guess it wouldn't be too difficult to add... given that one day i manage to make that simple circuit work Dead Banana

ringroad1 wrote:
I'm guessing you've got the 800R-ish resistor on that switch? Are you sure that's working correctly?

Now, after all those hours spent at debugging, i am not sure about anything... Is the earth flat ? Dead Banana
Yes, i have used a DPDT switch so i can get two flavours of resonance (one is using the original value, and the other resistor is a 680R one).

ringroad1 wrote:
Try checking the audio at different points along the circuit with one of these makeshift probes http://www.diystompboxes.com/pedals/debug.html - I'd start by looking at the input and output of every op amp.

Yes, i am going to do that, as well as the continuity test.

ringroad1 wrote:
Ah, stripboard is the best isn't it?

Ah ah ! Yes, i'm having a hard time with this Dead Banana
I succeeded with every PCB i soldered, but the veroboard is much more funky, to say the least help zombie

Quote:
Be very methodical. It's slow going and boring as hell but my money's on either a resistor leg in the wrong hole or a missing cut., You'll almost certainly find it if you have the patience.

Yes, that's indeed very slow, time-consuming, frustrating and boring, ah ah ! Dead Banana
But thank you all for all the help and advices thumbs up
kragg
Ok, so i used an exacto knife to avoid contacts between the veroboards bands, and the circuit is quite cleaner now (picture below).
I still don't get any sound of it, though.

I also processed the continuity test : i have marked in green the parts where the DMM beeps... but i don't know how to make a deduction out of it hmmm.....



Revok
Looks like your output is grounded. Are the jacks wired correctly? Those look like the Roland stereo jacks. Do you have a bad cable?
Revok
Just to be clear, when you test continuity from 5 to the green area of 7, it beeps?

kragg
Revok wrote:
Looks like your output is grounded. Are the jacks wired correctly? Those look like the Roland stereo jacks. Do you have a bad cable?

Hi
At first, i used plastic jack sockets. That was the first time i was using such enclosures : it seemed nice to gain a bit more space and to have jack plugs isolated from wires. But maybe it wasn't such a good idea.
I changed them for more classic jack sockets in metal, without any difference.

Quote:
Just to be clear, when you test continuity from 5 to the green area of 7, it beeps?

For the test, i had put an alligator clip on a ground point where wires meet, and ran the red arm of my MDD on the strips.


Sadly, i will not have much time today nor in the next days to debug the circuit (i wasn't expecting to spend so much time on this filter smile), so i will give reports when i'm back.
Thank you very much everyone for your great help ! :thumbsup
plushterry
When we say check for continuity, the process I would use is:

Put multimeter into bleep mode

Using the probes, not the crocodile clips, put one probe on track 1, the other on track 2.

Listen for bleep

If it does bleep, then you have continuity and you should check on the schematic if there's supposed to be continuity.

If it doesn't bleep, repeat the process for track 2 and 3, then 3 and 4 and so on.
kragg
oops
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