LowRider-voltages great until IC5

[Imuthant]

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: http://www.madbeanpedals.com/forum/index.php?topic=28592.msg277282#msg277282

...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!

[zgrav]

In addition to checking for continuity to the voltage pin(s) for IC5, check to see if the pin is shorted to ground. 

[Imuthant]

Thanks, checked that, and it's 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). Wasn't 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 

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

[rmfroyd]

If you figure this one out, please let me know.   I have built 2 boards with identical problems, all starting and stemming from IC5.

[Imuthant]

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.

[rmfroyd]

That makes 2 of us.  I think I could populate a board by memory at this point.

[Imuthant]

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!

[rmfroyd]

Yes, I would be interested in this as well.  I was just about to pull the trigger on a 3rd one, but I am going to hold off now.  The thing that sucks is I already have an enclosure finished for it.

I find it hard to believe that 2 of us made the exact same mistake, or had the exact same component failures on 4 boards.

I am currently working on my 98th pedal, but this build haunts me.  The only thing I can think of doing differently on mine is possibly hard soldering the transistors instead of socketing them.  I might mess with that this weekend.

Good Luck.

[rmfroyd]

Well, I replaced all of the transistors and IC's with ones from small bear.  I am getting 5-ish volts on pin 14 of IC5, but not 2.2mv on pin 8.  Voltage is constantly changing between .6v and .9v.   Fluctuating voltages and Q2 and Q3 as well as Fluctuating voltages on IC5 and IC6.  All problems see to stem with what at/after IC5.

[rmfroyd]

Since I can't let sleeping dogs lie....I bought a working lowrider.  Pin 14 on ic5 is reading 13.6mv on the working one, whereas the build doc states that it should be 7.9.  Unless madbean just left off the 'mv' on the build doc?