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Thread: Roland PM-30 Oscillating

  1. #1
    Supporting Member rf7's Avatar
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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

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  2. #2
    Lifetime Member Enzo's Avatar
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    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.

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    Education is what you're left with after you have forgotten what you have learned.

  3. #3
    Supporting Member rf7's Avatar
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    Thanks Enzo. I'll look into the grounds and re-check all of the soldering.

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