Why did the fuse blow?

Good question. I know we had a brown-out earlier in the week and I had to hit the power button on my amp (12v triggered from pre-pro) to get it running again - I guess there's a fail-off built in on power out. I've got a reasonable volume limit set on my pre-pro (-20) which is still 105dB give or take and the sug gain at the 7:30-ish position. I think if my kids had cranked it up the wife would have known. Must have been related to the brown-out. But why the secondary, 250mA fuses and not the 15A main fuse?? I found some 0.315A fast blow at RS, but I'm not willing to risk the warranty. The sub is also the only piece of audio equipment not plugged into a Brickwall box. Time to ditch the "surge" suppressor and run a cord to one of the Brickwall units.

Scott

A brown-out would have certainly caused the power supply to draw more current. The main fuse may be slo-blo and these secondary fuses may be fast blow. This could be the reason.

Do you know what the purpose of these secondary fuses is (ie. what are they protecting)? I have them on my EP600 but they are not described in the manual.

Not sure. At 250mA I'm guessing some sort of ground fault protection?? They are slo-blo, as well. Found a cross-reference to a gibson guitar amp, so I'll call the local guitar shop and see if they can help me.
To the best of my knowledge, the system was in stand-by mode during the brown-out, so not sure why they would have popped.

Out of curiosity, where are the fuses you are talking about?
I have the EP500. I only see the fuse near the power switch.

You may not have these fuses. They were added in a later version of the amplifier.

The ones to the right of m in Axiom on the back panel
[image]http://www.axiomaudio.com/gallery_disp.html?image=amp.jpg&title=EP500[/image]

Edit: Boy! I just can't seem to post an image to save my self... if I cut and paste the link, I get the image. What gives??

All linked image need to end in .jpg or .gif or similar. I peeked at the html source and found the direct link.

Thanks, Peter. So all I needed to do was remove the "&title=EP500" from the end? The things I miss at 2AM

Scott

That's not what I did. (just tried it and it doesn't work). On your original link, I went to my View menu and chose View Source. This shows me the page's raw HTML code. If you know html, it's easy to pick out the line that tells you where on the webserver the image is hiding. From there, it was just a copy and paste operation.

Ahhhhhh! Think I got it now... I had to piece it together ... "http://www.axiomaudio.com/global" from the source definition plus "/images/products/large/amp.jpg" from the click-box to get "http://www.axiomaudio.com/global/images/products/large/amp.jpg" then bracketed between image tags. Right?

Scott

PS: I found fuses at mcmaster.com, should be here tomorrow!!

img /img

That part I think I got

Mc Master delivered as scheduled and I'm rumbling away again!!

Scott

Rumbling...until the next brown-out.

Gonna see if the Brick Wall surge protectors help. Everything else is plugged into them and I haven't seen a dip, fade, flicker, crackle, nothing.

Scott

They won't help with a brown-out. Your best bet for that is a diesel generator with a sub-cycle under-voltage relay .

I have an older version of the EP500 without the fuses on the back panel. I had to return the unit to Axiom twice. On one of these occassions the Axiom technicians told me that the problem was a blown "internal fuse." I wonder if this had become an issue and is the reason Axiom now places these fuses on the back panel to make them accessible to the consumer.

My question (if anyone knows): If may EP500 dies again, can I access the fuses without returning the unit to Axiom?
Thanks for your help.

JC told me that they made the fuses user-accessible so that the amps don't have to be returned to the factory. If yours are now accessible (ie. you have the newer amp) then you can just change them when they blow. I sure would like to know what those fuses protect.

Since the EP400-600 have a digital DSP amp, I am assuming that they need those fuses to protect the inner electronics of the amp. whereas a normal sub doesn't have the digital DSP.

Hi a401classic,

These fuses are not required for the amp to work properly or to avoid damaging the amp. In fact I don’t think they are even required for either CSA or UL but CAS wanted them in there because we also have a CE rating on the amplifier. Originally they were internal because they are very difficult to blow; you would need a drop below 90 volts followed by a spike to blow them. Since this actually happened in a few instances we moved them to the panel for easy replacement. Two of my EP600s are the original prototype amps and they do not even have these fuses inside or out and I have never damaged my amps; and living in rural Canada big voltage swings are a fact of life. We can certainly send you some fuses for them if you like on Monday. Recently we started including spare fuses with every EP400/500/600 sub just in case. We did not realize they were a bit tough to find until we out-boarded them on the panel. I hope this helps you out a bit with your current blown fuse issue.

Thanks Ian. I've got plenty of back up fuses now. I live in an area that is prone to heavy lightning activity, which I'm sure now is what happened, in addition to being at the end of the power line. We've never lost an appliance, even after a direct hit... so far. Actually we did lose a UPS once, but the computer attached to it was fine.

Thanks a again,

Scott

Hi... just to be clear that's 5mm X 20mm 250Ma fuses, correct? McMaster's fuse selection is huge. What type fuse is it?

Thx!



Will Axiom also send extra fuses on request?