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PostPosted: Tue Nov 23, 2021 10:01 pm 
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I bought a Para. Comp kit in 2015, but it's rev 1.1. Finally built it this week. I have a specific question so I'm not posting pics yet.

Anyway, the Lo-comp (left) side works great. Lovely compressor, and the frequency knob lets me dial in a fat or thin tone as needed. But the Hi-comp (right) side doesn't work. If I turn the left side 'level' and 'comp' knobs all the way down (counter-clockwise), and turn the right side knobs all the way up, I can hear a very faint, very fuzzy tone that responds to my playing. The 'Frequency' knob doesn't seem do anything at this point.

I was pretty meticulous in the build, tested all the resistors, so I'm fairly confident everything is where it should be. But in bug hunting I found that the C100K dual-gang pot reads around 95K on the lower, underneath set of lugs (the top row on the component side of the board), but only around 26k on the upper, outside set of lugs (the bottom row on the component side of the board). That seems like a pretty big difference, but at 1/4 of the nominal resistance I guess I'd expect a little more signal.

So is this is a bad pot? Is the difference irrelevant? Is my problem elsewhere?


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PostPosted: Wed Nov 24, 2021 12:25 pm 
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It's never a good idea to measure components in-circuit. VR1b is directly in parallel with a 30k resistance, so getting a 26k reading would make sense. Furthermore, the low pass side of the state variable filter is more dependent on VR1 as a whole than the hi pass side. So if the lo pass section is working, VR1 is probably good. In fact, the entire state variable filter that splits the signal into hi and lo is probably working. The hi-comp out portion of the circuit is part of the lo-comp out circuit, so we can probably assume that that portion of circuit is working. That just leaves the hi-comp portion of the circuit, so that's the first place I would be looking for a problem. I can't say with absolute certainty that that's where your problem is, but based on your symptoms, that's would be my guess.

Please take voltage readings of....well all the ICs really, but IC2a and b are the main focus.

Do you have a signal tester? That would be handy as well.

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PostPosted: Sat Nov 27, 2021 5:33 pm 
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So it's not the pot. Cool -- thanks. I figured the problem was in the hi-comp side, since the part that's not working. I just wasn't clear on what role the pot played in that side of the circuit.

At this point, what good would a signal tester do me? I did already try to follow the board from component to component to test continuity, which I guess is sort of a signal, but since the PCB and the instructions don't identify which component is which in the schematic, it's not at all clear where to go next. And if you have voltages, why not put them in the instructions? Maybe a tech appendix or something.

BYOC got me started in this hobby, and I am grateful for that, but ever since I moved up to the intermediate-advanced kits, they seem like they're harder than they need to be -- the Stereo Analog Flanger (never got it working), the Green Pony (took two tries), now this. It's not just the technical difficulty, but also the instructions having obvious errors and omissions. Like I said, I was meticulous in this kit and really front-loaded my my effort to avoid exactly this situation. Maybe I made the mistake, maybe not, but my sense is that if it doesn't work now it's probably not going to.

I value my time, so I guess I'm not invested in what's a good idea from an engineering point of view, but more in what's an easy idea from a DIY point of view. If there are no easy ideas left to try, there's little value in me sinking hours more into this thing. If I'm at the point where I'm reverse-engineering BYOC circuits looking for bugs, I have the skills to build my own circuits - which I've started doing in the last couple years, and I seem to learn more that way. Plus there's no one to treat me like I'm wasting their time if I don't quite get it. Don't get me wrong: I assume the apparent condescension was unintentional, but I'd be more sure of that if anyone had fixed the Green Pony instructions errors I tried to point out two years ago. I checked, they're still there. Either you don't believe me or you don't care, but it's not a good vibe either way.

Point being, I want to build stuff that works, and if the message here is that I'm not sophisticated enough for your upper tier kits, that's fine. I really enjoyed the first few kits I built, but now I find I'm 100% okay with the idea that I've maxed out at BYOC. The point ultimately is music, and so when building time starts to take away from playing time, it's not worth it for me. There are other pathways I can explore, and what I have right now is a functioning compressor, it's just... not parametric. Nice idea, didn't work out, but Spectracomps are $100 with a coupon. So it seems like the best idea for me now is to roll with this build as is, and move on to other projects. That said, I really do appreciate BYOC providing me an on-ramp in the hobby. Thanks.


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PostPosted: Sat Nov 27, 2021 7:05 pm 
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There are a few things to respond to here. Disclaimer that we moderators are not BYOC employees.

A general word about tone. We're communicating in a text-only environment here, so no one has any nonverbal cues to play off of. It's just hard to pick up on subtleties, and people's attitudes, like condescension, will be even harder to perceive accurately. Add to that the fact that this hobby is full of science and tech people, who may occasionally fit the stereotype of not being particularly warm and bubbly—well… I guess I'd just say it's best to assume the best of other people's intentions. You'll usually end up being right. I promise no one here thinks you're wasting their time.

That being said, we do get a LOT of tech support threads where people are positive they've done everything right and don't post photos for a long time, and when they finally do, we point out a single resistor error or bad solder joint, and the problem is suddenly solved. I know it's a pain in the ass to upload photos, but it's really hard to do much troubleshooting without seeing the build. Frankly, it gets a little tiring after a while. Also, you're not discovering any "bugs" in the circuits. These kits have been successfully built hundreds of times.

I'm sorry your corrections to the Green Pony instructions didn't get added. I don't recall the thread in question, but if you link to it, I can make sure the team sees it again. Keith, aka forum member byoc, is already active in this thread. So he'll read this, and I think he's the only one who works on that stuff at this point. It's been a hell of a rough couple of years to run a small business, especially one that relies so heavily on the Asian supply chain, so I guess I'm inclined to give him a break on that oversight. I do think it's a solid idea to include voltages in the instructions. Maybe it's something BYOC could consider in the future.

Lastly, I'm sensing your frustration with a non-functioning build. It's understandable. It's super annoying when the stuff we build doesn't work right away. And FWIW, I'm actually 100% with you when it comes to your preference for DIY practicality over electronics science. You can go a LONG way in this hobby without any significant technical knowledge—ask me how I know. My encouragement to you is to stick with it. It's worth it in the end. Even if you have to use a signal tester. :wink: (And as for that, it is a far more powerful troubleshooting tool than the multimeter you've been using.)

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Last edited by sjaustin on Mon Nov 29, 2021 12:58 pm, edited 1 time in total.
omitted a word


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PostPosted: Mon Nov 29, 2021 12:28 pm 
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I try to approach tech support in a more clinical manner. Sometimes, I'll include a brief explanation of what I think the problem is in terms that may be a bit too technical for beginners or novices. I come off as condescending, that isn't my intention.

I don't recall what the problem was with the Green Pony instructions. It must have gotten lost in shuffle. If you link to the thread, I'll get to it asap.

Voltage readings provide a lot of information. So if you'd like help with this, I will need those. It may seem like a good idea to put voltage test points in the instructions, but that often times causes more problems than it solves for beginners.

The signal tester can confirm that the state variable crossover is indeed working. I'm only assuming that it's working at this point. If you're getting a full highpass signal at pin 12 of IC2d, then we could assume with a fairly high degree of certainty that the problem is in the hi-comp. We could also see if signal is coming out of IC2d and IC2c and track down signal inside the full wave rectifier.

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Please do not PM me. email is prefered. keith@buildyourownclone.com


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