Amp repair

[Nuthed]

Does anyone have any opinions about having components repaired at local repair shops versus sending them back to the factory for repairs? If the local shop has a good reputation does it still matter? Would they use the same parts? These are questions I will have to ask them I guess.

What I'm referring to is my prized RB980BX. My 16 month old son decided to pull out the cables from one speaker, something he had just seen me do when I replaced the connectors. The problem is I was playing music at the time. Well now the right channel has no output, so he must have shorted it.

[Kevin D]

Chances are it just blew a fuse. Something you or a local repair shop should be able to handle.

Kevin D.

[Nuthed]

Thanks.
Should I just pop the cover off and look for a blown fuse? Any idea where this fuse would be located?

[Kevin D]

Yeah just pop the cover and start tracing the right channel. I've never pulled a cover on a 980, but there's probably going to be several fuses per channel. You might need a multi-meter to verify if a fuse is good or not.

Kevin D.

[Nuthed]

Going to Radio Shack tonight after work, found 2 blown fuses on the right channel. I hope there isn't another circuit board under the large one. They were both 125 volt, 5 amp fuses.

[peterS]

id say dont
although it is common for this amp to blow fuses with no damage putting in a cold fuse in a damaged board will just fry it more
considering the circumstances damage is a definate possibility - id put in a lower amperage fuse first to see if it pops on start up
i sent mine in (not a fuse problem) for $40 shipping and they even did some upgrades

[Kevin D]

Different amp then the RB1080. Older and I'm sure out of warranty.

I also disagree on the fuse statement. If whatever over-voltage that caused the fuse to blow is still present, a new fuse isn't going to suddenly allow anymore current through then the fuse (and subsequent parts) will allow.

Being the channel went out while cables were improperly removed, I think we can rule out catastrophic unknown damage.

Kevin D.

[peterS]

Different amp then the RB1080. Older and I'm sure out of warranty.

I also disagree on the fuse statement. If whatever over-voltage that caused the fuse to blow is still present, a new fuse isn't going to suddenly allow anymore current through then the fuse (and subsequent parts) will allow.

Being the channel went out while cables were improperly removed, I think we can rule out catastrophic unknown damage.

Kevin D.

fuses blow due to current
the voltage will actually sag in such a situation
and yes a cold 5 amp fuse will allow higher levels of current longer than a 5 amp fuse that is warm

id say a near 0 ohm load is as catastrophic as one can do to the output stage of an amp

chances are that the fuses did there job by blowing before damage was done but if you can eliminate all chance by buying an additional $.50 fuse id do it

here is a simple chart for exceeding the amperage of a fuse and the amount of time it takes to blow

%of amp rating Opening time
110% 4 hours minimum
135% 1 hour maximum
200% 5 minutes maximum

so if its not already clear, upon startup a damaged circuit will generally draw more current than normal hence a lower amperage fuse will pop sooner preventing further damage while simultaneously signifying that there is a problem

[Nuthed]

$2.99 for a 4 pack of 5 amp 125 volt fuses. Used 2 of them.....kept them in my pocket on the way home so they stayed warm. Just kidding :T
Everything is fine and working great.

[wkhanna]

Yes. The type of fuse in this amp (I have two RB980 BX's I've been abusing for over 13 years) is a metallic filament with a fixed resistance just like a resister, in a glass enclosure typically referred to as a ‘bus’ fuse. When a short occurs in a circuit, current rises and causes more heat to be generated by the resistance of the filament. When the fuse sees current higher than its predetermined rating, the resistance created by the filament is converted to heat, and the filament will melt at a predetermined temperature.

I have had occasion to blow fuses more times than I care to admit in my amps; at least the times when it was MY fault. From power surges and lighting strikes, to brain fade acts of hooking up speaker wires with the system on; in all cases, simply replacing a blown fuse has restored my work horses back to their former performance while keeping the SPCA and audiophile police from my door.

Turn-on current spikes may cause more damage in an already damaged circuit, but maybe we both are just lucky fools!

All I know is these amps have proven to be rock solid and well designed, IMHO!