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Author Topic: No lights, no display, no sound  (Read 1473 times)

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emunstar

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No lights, no display, no sound
« on: Time Format »

I've got a MP-1 that died on me a few years ago. I had it at a gig when the singer inadvertently killed the stage power while hanging a backdrop. The unit was on at the time but once the power was switched back on my MP-1 had no display, no light, and passed no audio. Looking inside I can hear the transformer hum and the tubes are glowing so there is at least power up to the tubes. Any ideas? The power was shut off and rapidly turned back on in a matter of seconds so my best guess is something on the unit has blown. Nothing inside appears burnt, there are no swollen capacitors or other visible signs of component failure.
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MarshallJMP

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Re: No lights, no display, no sound
« Reply #1 on: Time Format »

If you have a backup of your presets you could try to pull the RAM chip out and back in,sometimes with a brown out the RAM can become corrupt,not always but i've seen it before.

But first can you measure the voltage over the 3 big caps near the power supply?
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emunstar

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Re: No lights, no display, no sound
« Reply #2 on: Time Format »

Thankfully there are not any presets that I would mind erasing. I'll try pulling the chip. What are the voltages I should be seeing at the caps?
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MarshallJMP

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Re: No lights, no display, no sound
« Reply #3 on: Time Format »

The 3300 µF cap should have 8 to 9 Vdc,the 2200µF caps should have around 20-22 Vdc
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