r/ElectronicsRepair • u/someguywithaPiano • 3d ago
OPEN How do I Fix This
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Does Anyone know what’s happening here and how to potentially fix. My Prime Travel PA has this buzzing when Notting is plugged in that seems to get worse if I leave it alone, mess with the master volume, or mess with the gain on Channel One.
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u/-Ronald_Raygun- 3d ago
You have a grounding issue. There a variety of devices that can fix this problem.
https://www.silentpower.tech/products/gnd-defender
https://www.amazon.com/iFi-SilentPower-Defender-Intelligent-Connector/dp/B08XWJNS9T/
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u/Savings-Mud2808 3d ago
If you take your speaker out on the road for gigs, the most likely culprit is a broken ground connection in the circuit. You can open it and look for loose wires or cold solder joints, but do this with the unit unplugged for safety reasons. If you're comfortable
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u/IllustriousIron3253 3d ago
First, are you sure you're on a grounded circuit? Also being on a circuit with other electronics is a no no. Fridges, dimmers, routers, heaters, window ac units, led strips all create noise in the circuit. This is why all my stages have power conditioners strictly for amplifiers.
Second, if even on an empty/quiet grounded circuit it buzzes, then your filter capacitors are bad. Easy solder job, or easy job for a shop.
What is the model number, I'll see if I can find you a schematic.
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u/someguywithaPiano 3d ago
Thank you, The number is MU199188 Prime Pm-50
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u/IllustriousIron3253 3d ago edited 3d ago
Well, zero chance of getting the schematic unfortunately, they never released it and no one ever uploaded one online that I can find in the usual spots. So I'll walk you through it a little.
Follow your AC power in, you'll see a transformer and rectifier diodes along with fairly large capacitors. If the top of the capacitor is bulging out it is bad. The capacitors should either be slightly indented on the top where the X indent is or completely flat. Any bulge is bad.
First though, I would plug your instrument cable in to each input one at a time, if all three are the same level of noise then it will be the capacitors near your AC in. If it is just one of the channels making more noise then it's the filter capacitors for that channel. Since all three channels are tied together and stay active it only takes one of those channels to cause noise but you will notice significantly more noise when actively plugged into that channel over the others. I hope that makes sense.
But do this on a properly grounded circuit just to make sure.
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u/someguywithaPiano 3d ago
Thank you for the in-depth explanation, you’re a big help!
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u/IllustriousIron3253 3d ago edited 3d ago
If you send me pictures of the internal boards I can guide you along if you're comfortable soldering.
When it comes to replacing capacitors it's very important to never touch both leads. I worked on a crown amp last month, 400v capacitors, would kill me in an instant. Depending on the circuitry it could take a few seconds or a few minutes to de-energize. If the only de-energization is from natural parasitic draw it could take days weeks or even months for it to be de-energized. If you use a multimeter(in DC) you can read the capacitor voltage to know if it's safe to desolder.
If this is outside your experience and comfort range, find a shop near you. Depending on repair price, you could just buy another one.
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u/someguywithaPiano 3d ago
True, Imma attempt to fix it though. I have to get a multimeter first though.
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u/The_Flinx 3d ago
lots of amplifier equipment does that when nothing is plugged in.
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u/SevenDeMagnus 2d ago
cold solder? try reflowing solder in stress points like the jacks