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Did I blow my amp?

I am not an electronics guy, but need to ask for some opinions from people who are...and hopefully help me find the right solution to fix my amp.

I have a Roland Cube, which I basically use as an amplifier to play music t hrough, or my guitar. The other night I had my laptop plugged into it, play ing some recorded music. I had the music coming out of the laptop turned of f, the amp turned off, and plugged into the laptop (via a mini-plug wire co nnector).

I had accidently touched the volume control on my laptop, however, and didn 't see that I set the volume at nearly max output, and started the music pl aying. There was no sound yet, though, since the amp was off; so when I fli pped the power switch on the amp, the sound came blasting out in a huge way , though it was garbled and static since it was overloading the system.

Pulling the plug immediately, when I later tried to play music through the amp again at proper volume, nothing comes out but a steady hum. I hear the same hum if there not even anything connected and playing through it.

So my question is: what damage did I likely do? Can it be fixed? Is there a ny other testing I can do to determine what was damaged?

TIA,

--Rick

Reply to
Rick Casey
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Maybe when yuo yanked the cord you could of broke a wire in the cord or a solder joint where the plug is inside the unit.

Jamie

Reply to
M Philbrook

If it is a loud 120 hz hum, chances are the power amp section is blown. (Shorted parts)

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Reply to
Chuck

Look for internal fuses. Generally what you did will not damage most amps.... But it may well pop internal fuses or links. But not always. Next would be the output devices.

Reply to
pfjw

Thanks for the tip! Will see if I can find that...

Reply to
Rick Casey

** The first Roland cube was the "Cube 40" released in 1978, then followed Cubes 20 and 60 and then too many new models to count. Roland claim to have sold over 1,000,000 Cubes of all the various sorts.

Which one have you got?

** Was that the power plug ?

** Answer the first question and maybe we can make an educated guess.

One possibility is the input jack ( or the PCB it is mounted on) has broken. All depends on which model Cube you have.

... Phil

Reply to
Phil Allison

I'm with Jamie here. Have you powered up the amp with ONLY the speakers hooked up? No other cables going to the inputs.

If still hums, does the hum volume go up/down with the volume control? This could indicate a problem in the pre-amp section.

If the hum level is steady, then the problem could be a blown fuse on one of the power amp rails (B+ or B-).

John :-#)#

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Reply to
John Robertson

** Roland Cubes are combo amps with the speaker internally wired.

** None that I have seen use DC rail fuses, they normally have fuses in the two AC lines coming from the transformer. If one of them fails, the amp continues to work. When both fail, it goes silent.

... Phil

Reply to
Phil Allison

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