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Roland PM-30 Oscillating

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  • Roland PM-30 Oscillating

    I've got a Roland PM-30 that has ultrasonic oscillation (667Mhz) on all of the speaker outputs, and this is not a switching power supply. The unit came in with both fuses which feed the 5V rail blown. I replaced those and now the oscillation is occurring. I see it on all of the power supply voltage rails, but the line outs do not have the oscillation on them. So, I feel like it is a power supply issue. I am not blowing those fuses at this time. Any ideas?

    Roland PM-30 Schematic maintenance manual -Roland-Service manuals|user manuals|schematics|drawings|circuit diagrams|Download-www.circuit-encyclopedia.com

  • #2
    How do you download it from that site? the big DOWNLOAD buttons seem to want to download some DOC to PDF conversion. All I want is the schematic.

    never mind, I found it on Nick's site:
    http://bmamps.com/Schematics/Roland/...e%20Manual.pdf

    it is probably the power amp oscillating for all it is worth, dragging the power supplies into the game in the process. A missing ground somewhere could also allow that. Oops, scratch that, it is a digital amplifier, so it may not be oscillating, but it sure is full of high frequency trash. Still could be grounding.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Thanks Enzo. I'll look into the grounds and re-check all of the soldering.

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