Sound Skulptor forums
Build help and troubleshooting => EQP501 Passive Equalizer => Topic started by: heathwj on January 08, 2021, 04:13:40 AM
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Hi! I built the EQP recently and it looked good voltage-wise when i tested it. I went to use it for the first time and it was amazing! Everything worked as expected and sounded fantastic.
I was using it on a project today and it was fine in the beginning and then it started to create a lot of distortion, it started as subtle but then became totally distorted and low volume. Now the EQ won’t play any signal when it is active, signal still gets passed through when it’s bypassed.
I have used it probably for a total of 2 hours in total over the last 2 days and had no issues until now.
Any idea how i can bring this beautiful EQ back to life? Perhaps a component was faulty and died very quickly?
My unit does generate a bit of heat and an “electrical smell” but no burning and smoke or anything dramatic. Just an old school electronics smell.
Thanks for your help.
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Well. Just pulled out the op-amp and one of the resistors burned up. Not sure if it damaged any of the other components but the bottom of the board looks bad in a few places now :(
This is my first time troubleshooting any DIY gear but this certainly looks the culprit. Is my whole SK-25 fried?
Guess the smell was a little too much smell after all :/
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Last update. Two resistors on the op-amp burned out. It was R12 and R13 (both 5R6 resistors i believe).
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It looks like your SK25 is the culprit. This will be confirmed if you get any DC voltage on TP2.
- Check that R1 is not touching the vertical PCB and the diode D5,
- check that the 4 solders on each vertical PCB are making good contact,
- check that all the component leads are trimmed as short as possible. None must be touching any component underneath.
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Hey JP. Thanks for the reply! I spent some time digging into it more and I noticed I missed a step when building my SK. I missed soldering the vertical panels to the main board :/. I assume that resulted in some part of the board getting too much power? Would it be worthwhile to salvage the board or just buy a new SK-25? I was able to remove to the burned resistors but like I mentioned, the areas where the resistors burned looks pretty ugly now. I also don't have any 5R6 resistors in my components bin. Please let me know what you think my best option is.
Attaching some images for you to judge. All my joints were nice and shiny prior to it burning up, but i'm not sure how this kind of mistake messes up the other components. Thanks.
(https://i.ibb.co/nQPsLKj/IMG-5867.jpg) (https://ibb.co/GCHv5rR)
(https://i.ibb.co/Tv3dStq/IMG-3631.jpg) (https://ibb.co/cgnVHQX)
(https://i.ibb.co/7zZrQqv/IMG-7151.jpg) (https://ibb.co/8BfPbHM)
(https://i.ibb.co/ZJfSdTm/IMG-6919.jpg) (https://ibb.co/0XnKqJt)
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I would recommend that you start a new one because all the transistors are DC connected and one failure usually causes other cascading failures.
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Thanks JP. Ordered a new SK. I’ve built a few other DIY kits so far but i just started last year, so it was just a novice mistake. I was bound to make a mistake at some point lol. Thanks for your help. I’m blown away by the quality of your kits, absolutely top quality. Excited to get my EQP back running.
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Hi did you notice how hot the op-amp was running?, cause i just build 4 of them and using a test jig, i notice that 3 o them run very hot, one is cool, perhaps to hot make the whole opamp to fried also.
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On your pictures, it seems that you didn't make the 4+4 solder joints that link the main PCB to the other 2 vertical's.
Without these joints, the DOA cannot work and is very likely to burn.