Do We Need/Want a BBD Tester?

Stickman393 said:
Weird, grand total on my JLCPCB is like 40 bucks for 5 boards. UPS shipping is like 23, customs is like 10.80. Still nearly twice the cost of the boards. Crazy.
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Just received the first batch from OSHPark. They look good. Building out now but still need the dip switches and jacks. (Just ordered and should be here Friday.) I'll let you know how the first test goes when I can finish the first build.
 
@Stickman393 . . . . . . Houston, we have a problem. While I've yet to actually fire up on e of these new BBD Tester boards, It seems there is a layout problem with the MN3005 footprint.

BBD_Tester_Build_00_Bad_02.jpg

Unfortunately, I didn't discover it until after I fully built it out. Kinda bummed that I missed this on all iterations.
BBD_Tester_Build_00_Bad_01.jpg

Could you please correct and resubmit? (If I could work with KiCAD, I'd fix it myself, but my KiCAD-fu is non-existent.)
 
Son of a bitch!!

Gah. Yeah, can do. A quick workaround to make it so the existing one work would be to use some bus wire and perfboard.

I swear that footprint was part of the kicad stock library. Gah. I'll figure it out' I've got a few MN3005s that I can test against.
 
Thanks! Did your PCBs arrive yet?

And, is there any way you could convert the PCB projectile(s) to EasyEDA?
 
Got the grbls uploaded to the dropbox folder. Fucking thing aint a Dip-8-16, it's a Dip-8-14. Gah.

I made some edits to the files as well. I'll see if I can get this in easy EDA format...dunno whats involved with that.
 
A'ite, added an easyEDA import.

Hopefully that works. Unfortunately that program makes my laptop huff and puff like it's about to die.
 
Thank you! With the new Gerbers, I have to ask, does this look right to you? I just uploaded the Gerbers to JLCPCB and it appears the solder mask is covering the copper on the two new holes for the MN3005 footprint. It doesn't appear right, as if the solder mask and/or ground plane needs to be adjusted. (Circled in RED)

And thanks for the EasyEDA conversion file. Unfortunately, it's borked - all the PCB runs are still in their raw net form, just a bunch of lines criss-crossing each other, as if the none of the tracing has been done yet. Thought I'd make the request to see if would take. It's common problem going from KiCAD to EasyEDA. The schematic converted fine tho.

PCB2.png

PCB2_back.png
 
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Cybercow said:
Thank you! With the new Gerbers, I have to ask, does this look right to you? I just uploaded the Gerbers to JLCPCB and it appears the solder mask is covering the copper on the two new holes for the MN3005 footprint. It doesn't appear right, as if the solder mask and/or ground plane needs to be adjusted. (Circled in RED)

And thanks for the EasyEDA conversion file. Unfortunately, it's borked - all the PCB runs are still in their raw net form, just a bunch of lines criss-crossing each other, as if the none of the tracing has been done yet. Thought I'd make the request to see if would take. It's common problem going from KiCAD to EasyEDA. The schematic converted fine tho.

View attachment 96223

View attachment 96224
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Well. Shit. Yeah, I gotta re-export those gerbers. Looks to me like the new drill file got mixed in with the old design. Dammit.

Now you see the folly of stickman.

"Its done, NEXT!"

"No, I think I found an erro.."

"I SAID NEXT"
 
I just tried to test an MN3007 with circuit fully built out and populated with just an MN3101 and the MN3007 and it fried the MN3007 - it got super hot. I used a 9V battery to test, with a negative center plug. I double-checked the voltages at the appropriate pins before I inserted the chips and they looked good. Something else is wrong too. The MN3101 is fine.
 
One small thing I'd like to request . . . . Please reverse the polarity of the DC jack so it is positive-center. That way, when the toggle bat is switched toward the user, the MN30xx series (not the MN32xx) is up for testing. It matches the silkscreen print on the PCB.
And remember please, the silkscreen labeling on the top of the board needs to be double-checked. I'd like the labels to show up like in the attached image.

BBD_Tester_PCB_OSH.png
 
I checked my schematic, everything looks like it *should* work.

I'm not super keen on switching the barrel jack: the reason being that it's currently configured for center negative, which is what 95% of effects use. It *will* work either way, just the throw of the switch will be reversed. I'd be happy to switch the orientation of the switch though: that's easy enough.

The LEDs should still light depending on how the circuit is configured (that is, positive ground or negative ground).

Positive ground lights the MN30XX LED: the voltage applied to VDD on all of the ICs is "negative" in comparison to the ground.

Negative ground lights the MN32XX LED: the voltage applied to VDD on all the ICs is "positive" in comparison to ground.

I'm gonna ask if folks can take a look at my drawings here and double check my work. I'm not seeing anything in here that should have led to the MN3007 getting hot. Maybe I didn't space out my traces and pads enough and got a short in the PCB manufacturing process? Could you post close up photos of the board on each side so I can compare to the way it was laid out?

Maybe I should change how I deliver the rails to the ICs. Right now I have a ground plane on both sides of the board: i could do a VDD on one side and a Ground on the other.

Anywho: someone get a second pair of eyes on this thing for me? I wanna make sure that I'm not missing anything.

Screenshot 2025-05-28 150758.png
 
Without excuses and all humility, I have to back-track my last two responses. In my dyslexia, I found four issues with my testing:
1) I was coming down with a fever yesterday morning when I did the tests. So I wasn't thinking clearly. (All better today and embarrassed about the next two.)
2) For some reason, I was thinking the MN30XX series were POSITIVE voltage devices and MN32XX were negative.
3) I had the two LEDs positioned backwards - so they deceived me about the polarity & series being tested.
4) The MN3007 survived the wrong polarity, but the MN3101 did not.

And after rethinking the DC jack polarity request, I have to agree with you that negative center is the better way to go.

I also agree that we should have some more eyes on the project for oversight. (Thanks!)

Now that my head is cleared up today, I'm goona correct the LED polarity issue and re-test and get back to you.
 
Now that the forum is back up-n-running . . . .
[EDIT - 5:46pm May 30, 2025]
I did some more testing, ensuring I had the polarities correct and all, and found that no signal gets thru circuit. I haven't tried to trouble shoot it yet (audio probe, scope, etc) but it should pass signal once the 500K clock trimmer is adjusted properly. The way to adjust it is simple. Just have the appropriate chips in place, the toggle in the correct position for the chipset, power up and put a signal to it. (I just use my guitar.) Tweak the 100K bias trimmer till sound can be heard. That's it. Then, to test the BBD, listen for the pitch wobble/change while turning the 500K clock trimmer. If you can hear the pitch change while slightly turning that 500K clock trimmer, the BBD is good.

Right now, I get no signal passing at all. I'll poke around some more tonight and share what I find.
 
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Crazy Cat is a G.

The good thing about working with stickman is that he's a fuckin n00b that has a good 10 year long career behind him of being wrong as an HVAC mechanic, so every time something goes wrong he assumes he is the one at fault.

So, no worries homie.

Question....do you have the correct DIP switch depressed? Should be channel 5 + 6.
 
Stickman393 said:
Crazy Cat is a G.

The good thing about working with stickman is that he's a fuckin n00b that has a good 10 year long career behind him of being wrong as an HVAC mechanic, so every time something goes wrong he assumes he is the one at fault.

So, no worries homie.

Question....do you have the correct DIP switch depressed? Should be channel 5 + 6.
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Fair enough. And thank you.

And to continue a vein of submissive humiliating admissions, it hadn't even occurred to me to use the DIP switch. I assumed it was reserved for just the MN3011. Looking at the schematic again, it's clear that DIP switch pin #5 must be closed for testing MN30XX/MN32XX series and that DIP switch pin #6 must be closed for testing MN3005/MN3205 series. (DOH!)

Today is full of other grown up responsibilities and re-examining this on the bench will have to wait for tonight.
Thanks for hanging in there with me. More later tonight.
 
That change was made to limit the amount of components needed...made for a total of 8 fewer resistors and a smaller dip switch.

MNXX07S and xx05s both have dual outputs that I typically see joined together by a pair of resistors. I *think* it's a means to make the output capable of driving two discreet signals for stereo. all three share dip output 5/6, but 1-4 are for the 11 exclusively.

I kinda wanted to make that go the other way, but I had already done the layout and making that change woulda seriously fucked up the flow of the traces.

Yes, I could have used vias. I just really don't like to.

I've got a good story about a piece of conduit that I expertly bent after about 5 failures in the bone pile.
 
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