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PostPosted: Thu Jul 02, 2020 7:20 am 
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So I've had a built script 90 for almost a year now. I haven't used it that often but I just dusted it off and it is not functioning correctly anymore.

The pedal turns on, LED works, sound is passed through and there is even a subtle tonal shift when its engaged but otherwise it's very static. If I had to take a guess, the LFO of the modulation is not working anymore. Any run of the mill troubleshooting I could do to check what and why something like this could suddenly go wrong?

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PostPosted: Thu Jul 02, 2020 7:22 am 
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The cause of a pedal not working when it used to work is almost always that the soldering didn't hold up. The most likely fix will be to go through and reflow all your solder joints. This post has lots of details about that process.

That said, feel free to post some photos so we can give you some more detailed help!

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PostPosted: Thu Jul 02, 2020 11:16 am 
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Old battery? Maybe try adjusting the trimpot?

Like sjaustin pointed out, if a pedal just suddenly stops working and you're certain it's not because the power supply, then it's most likely a problem with your soldering/wiring.

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PostPosted: Fri Jul 03, 2020 9:34 am 
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Thanks for the help,

Here is the gutshot. I suspect the oscillator isn't working anymore on the LFO, which component is that? I'll try resoldering that first.


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PostPosted: Fri Jul 03, 2020 10:44 am 
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It's hard to evaluate the quality of your soldering without seeing the back side of the board (and ideally a bit larger of a photo, with better light), but I do see several joints that look like they could use some more solder. Generally we want to see the solder flow through from the back side and fill the eyelet all the way to the front.

Did you try adjusting the trimpot? Worth doing that, even though I think you're going to end up doing the following:

Try reflowing all your solder joints. It won't take any longer than identifying pertinent ones, locating them, and touching them up. This step fixes almost all faulty builds. This post has lots of details about that.

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PostPosted: Wed Jul 08, 2020 12:08 pm 
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Thanks for the help,

So I resoldered everything. The pedal doesn't pass a signal when engaged now. (light works, signal when it is powered off).

Below are photos:

Image
Image


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PostPosted: Wed Jul 08, 2020 12:23 pm 
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Please take voltage readings of all the op amps.

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PostPosted: Wed Jul 08, 2020 12:31 pm 
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byoc wrote:
Please take voltage readings of all the op amps.

In case you're not sure how to do this, here's the process:

To measure the DC voltage level on the op amp pins, set your multimeter to the DC voltage mode, indicated by a solid line above a dotted one. Use the 20VDC range setting if it's not an auto-ranging meter. Your power source needs to be connected and there needs to be a cable in the input jack. If the pedal is assembled into the metal enclosure, put the black probe into one of the corner screw bosses of the enclosure--this is your ground connection. If the "guts" are out of the enclosure, use the sleeve tab of the input jack for the ground connection. Then touch the red probe to each point that you want to measure. See the left side of the image below for the numbering of the pins.

Image

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PostPosted: Wed Jul 08, 2020 12:36 pm 
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OK will do soon. Should all the ICs give similar readout on each pin?


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PostPosted: Wed Jul 08, 2020 1:25 pm 
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beachbuminthesun wrote:
Should all the ICs give similar readout on each pin?

No. Depending upon their function in the circuit, some will give steady voltages and some will fluctuate markedly. Refer to the image below for the numbering of the IC's and report your results accordingly:

Image

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PostPosted: Thu Jul 09, 2020 4:07 pm 
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OK, measurements attached, hope I did that right...


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PostPosted: Thu Jul 09, 2020 5:16 pm 
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Did you accidentally plug in a positive tip power supply at some point? If those voltage readings are indeed correct, it certainly looks like that's what happened. Are the op amps getting hot when you have the pedal plugged in?

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PostPosted: Thu Jul 09, 2020 8:04 pm 
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Never plugged in a positive power supply, it's always been battery or now with my testing, directly into a truetone 1 spot. I don't have any pedals that require center positive so I coud'nt screw that up even if I did it on purpose.


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PostPosted: Thu Jul 09, 2020 8:07 pm 
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OK but I did just realize a giant mistake. OP amp 6 is backwards. I even soldered the dip socket backwards. What's weird is that it was still working before. I'm going to flip it now and see if it changes anything


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PostPosted: Thu Jul 09, 2020 9:03 pm 
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OK that seemed to have solved my problem. Very odd. I seem to have soldered a bunch of the sockets backwards.

I had a functioning phaser, then I didn't, but I never messed with anything in between those times.

anyways it all seems to be working now.

slightly off topic question, but what is there reason I wasn't getting a wet signal until I screwed in the lugs for the jacks and footswitch?


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PostPosted: Thu Jul 09, 2020 9:13 pm 
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I should have caught this before, but looking at the large photo that you posted, four of the op amps are inserted backwards! Only IC's 2 & 3 are oriented correctly. I find it very hard to believe that the circuit could have worked properly in that condition. You can try switching these four op amps around and see if the pedal works, but I wouldn't be surprised if some or all of the four were damaged, accounting for the incorrect voltages evident in your testing. You might want to just go ahead and purchase four replacement UA741's.

Any chance that somebody might have been fooling around inside the pedal recently??

BTW, the orientation of the sockets are inconsequential--the notches in them are just a visual prompt for correctly inserting the op amp itself.

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PostPosted: Fri Jul 10, 2020 6:59 am 
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Well, it seems to be working alright now. I'm sure no one has been inside it. But I did take out the ICs do resolder the border, so the top photo is how they were originally. I'll take some measurements later today and post to see if they look alright.


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