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Messages - Imuthant

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Tech Help - Projects Page / Re: LowRider-voltages great until IC5
« on: July 11, 2019, 07:22:33 PM »
Alright....I bought another LowRider PCB, rebuilt it from scratch, double checking component values with a meter as I went. I have the exact same issue with this one. All voltages are about right until pin 14 of IC5. I get 0v instead of 7.9v. No audio passes when the pedal is switched on. Curious to know if there are any success stories from this run of PCBs? I've built 10 other pedals successfully, but both of these attempts have left me stumped. Any further ideas would be WONDERFUL...considering the time I've put into this one. Thanks!

Tech Help - Projects Page / Re: LowRider-voltages great until IC5
« on: April 26, 2019, 04:16:06 PM »
Nothing positive to report, unfortunately. Checked several times for any shorts, problematic components, etc...eventually started probing all over the place, but the issue just doesn't make sense to me. First time that I haven't been able to solve a problem after some extensive troubleshooting, but that's where I'm at.

Tech Help - Projects Page / Re: LowRider-voltages great until IC5
« on: April 19, 2019, 11:01:21 AM »
Thanks, checked that, and itís not shorted to ground. I removed the socket (messy process) and put a new one in. Got a bit weird from there. I was getting about 7v on pin 14, which was promising, but now I was only getting .5v on pin 12 (rather than the 4.8v from before). Wasnít getting continuity between pin 12 and R51, so I wired that directly. So...when I next checked voltages, I got 4.8v on pin 12 again, but back to 0v on pin 14  :o

This is a bit confusing to diagnose, as I know I may have slightly damaged the holes for IC5 during the desoldering process. Iíd like to keep probing around, but Iíll be out of country for the next week. When I get back, Iíll be able to keep troubleshooting...

Tech Help - Projects Page / LowRider-voltages great until IC5
« on: April 17, 2019, 05:42:54 PM »
No output when I first powered up the Lowrider. All the voltages looked good until pin 14 of IC5. I had 0v instead of 7.9v...

I saw this post:

...and my voltages/issues are pretty much the same for. All good (just a hair lower) until pin 14 of IC5. I'm trying to remove the IC socket now, in case it is somehow a bad socket, but I did have continuity from the bottom of the PCB to pin 14, so I can't imagine it is. I tried another LM324 (pulled from a working Small Stone build) with the same outcome. Any other ideas? Thanks!

After probing around and checking voltages to locate the problem, the issue ended up being embarrassingly simple...turns out RB2 was actually the pedal that was working properly, whereas RB1 wasn't biased correctly.

There was an accidental "sweet spot" (for me at least) exactly 1/4 turn ccw from the proper "bias" trimmer location. That resulted in much less voltage going to pin 3 of the mn3007 and much lower overall gain. The weird thing is, I initially preferred the improperly biased pedal, because after turning the gain trimpot all the way up, it was still usable gain-wise, and the output was smoother and less overdriven/dense.

Turns out that Attack Decays are supposed to sound like that, so I rebiased it and lowered the gain trimpot all the way. Sounds great, of course, I had just never heard one before. I can probably blame the feedback difficulties on my Harmony Rocket. Thanks for the help!

 Thanks! Iíll check all of those once I get back home.

So I built two Rustbuckets at the same time, with the same parts. The second one was for my bandmate. First one sounded great right off the bat, really great circuit...and I just "biased" the second one and it's much louder.

On the Rustbucket 1 (sounds great) the gain trimpot is nearly maxed. On Rustbucket 2, even with the gain trimpot all the way down, its significantly louder than RB1. Even at low amp levels, RB2 either feeds back, or feels ready to feed back.

I've double checked components and orientation, and everything looks to be the same (i.e. the edge switch is off on both)

I recorded some audio on my phone real quick, where both pedals have the pots at the same settings. The iffy pedal, RB2 is played first. Then I swapped pedals and played the same notes on RB1. RB1 sustains longer and more smoothly, probably because the difference in gain is effecting the interaction of the sense/attack/decay controls.

Any ideas as to what might be causing these differences in the second build?

(I can't get the audio file to load...I need to look into how to attach audio...)

Tech Help - Projects Page / Re: TOTAL RECALL - very low voltages on all ICs
« on: September 27, 2018, 04:05:23 PM »
Sorry for the delay! I've been moving and had to put projects on hold. I made the huge mistake of skipping sockets for every IC but 6, 7, and 8 (I know, I know...I used my sockets up on other projects and didn't want to wait...) so the desildering process was pretty rough, but they are all out now. I tested after removing each one with no change to voltage at the beginning of the power section. After that, I just took the regulator out as well, and that left no voltage on the far side of R57. Any idea what to check next? I might as well keep taking it apart, since I'll need to buy several new ICs and sockets...

Tech Help - Projects Page / Re: TOTAL RECALL - very low voltages on all ICs
« on: September 16, 2018, 09:28:44 AM »
Great, I'll try that next. In testing the positive side of the diode and GND, I get 1.6M ohms, and then 3.06M ohms when reversing the probes.

I only got -23.8 when it was plugged into the circuit. I remember testing it by itself, and it was much higher. Just check again, and it started around 34v then kept crawling up...

Tech Help - Projects Page / Re: TOTAL RECALL - very low voltages on all ICs
« on: September 15, 2018, 02:16:09 PM »
Yikes! I just really realized I used a cheap cap for C42 that is only rated for 25v instead of 35v...maybe that is causing some issues...

**edit - scratch that, I was looking at some spares. It is a 35v cap that I bought from Tayda.

Tech Help - Projects Page / Re: TOTAL RECALL - very low voltages on all ICs
« on: September 15, 2018, 02:12:58 PM »
Thanks for the response! (I've been a bit busy at work until now.)

Double checked at the orientations, didn't see any solder bridges, reflowed at the joints in that part of the circuit and cleaned the flux. That didn't solve it, so I've removed those two caps (C42 and C43) but I'm not entirely sure how to go about testing between the power rail and GND in reference to the diode? Where exactly is a good test point for the power rail? Appreciate the help!

Tech Help - Projects Page / TOTAL RECALL - very low voltages on all ICs
« on: September 13, 2018, 03:48:10 PM »
Hey everyone, first time posting. Just started the biasing procedure on my Total Recall build, but couldn't get anything but the clean signal when probing around early on in the circuit. Nothing on the BBD. So I started checking voltages.

 The power jack brings in -23.8v, and R57 (the 240r 1w) has -23.8v and that end, and only -0.8v on the other end.

So of course the regulator gets hardly any voltage, less than a volt, and the same goes for IC1.

I double checked and mouser did send me a 1 watt 240 ohm resistor, and I checked it for resistance to make sure it wasn't dead, and I got 240 ohms on my meter. Any ideas on fixing this issue? Thanks!!

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