MY 900 is blowing fuses

[Reckless Abandon]

I had a thread over the weekend that my amp stopped working. It was the fuse as suggested. It now has blown 2 fuses as soon as I turn on the power. On the back of the amp it say with 110/120 volts use a 4 amp 250v fuse. They do not make those, at least lowes did not have them. I bought 3 amp 250 v. The 5 amp ones were 150v. I know it is not the same fuse that is supposed to be there but the fuse that was in the amp since MArch (EBAY, i had not changed the fuse) was only 2.5 amp. So what is wrong? The tubes are only 2 weeks old, the thing sounded fine until it stopped.

 

[kevlar3000]

Re: MY 900 is blowing fuses

Definately get the right value fuse or serious damage could result. Could be a bad tube, blown resistor ( screen grids ??). If in ? don't hesitate to get it to a tech.

 

[MrHeavyMetal]

Re: MY 900 is blowing fuses

I had a thread over the weekend that my amp stopped working. It was the fuse as suggested. It now has blown 2 fuses as soon as I turn on the power. On the back of the amp it say with 110/120 volts use a 4 amp 250v fuse. They do not make those, at least lowes did not have them. I bought 3 amp 250 v. The 5 amp ones were 150v. I know it is not the same fuse that is supposed to be there but the fuse that was in the amp since MArch (EBAY, i had not changed the fuse) was only 2.5 amp. So what is wrong? The tubes are only 2 weeks old, the thing sounded fine until it stopped.

Take it to an amp tech ASAP. A lot of Marshall JCM 900's are biased too hot.

 

[Reckless Abandon]

Re: MY 900 is blowing fuses

I guess it will be off to a tech. What sucks is the same guy does all of the work for all of the music stores around. It may be 3-4 weeks before I get it back.

 

[Reckless Abandon]

Re: MY 900 is blowing fuses

Take it to an amp tech ASAP. A lot of Marshall JCM 900's are biased too hot.

So they may have screwed up when they put in my new tubes and biased the amp? My luck.

 

[MrHeavyMetal]

Re: MY 900 is blowing fuses

So they may have screwed up when they put in my new tubes and biased the amp? My luck.

you could stick some new tubes and fuses in it, then turn the power on. if the tubes are glowing very brightly (and I mean much more than normal) then get it checked out.

 

[Reckless Abandon]

Re: MY 900 is blowing fuses

I do not have any new ones. If I am going to spend 100 bucks I might as well take it in.

 

[ErikH]

Re: MY 900 is blowing fuses

Have the power tranny checked too. If the tubes glow really bright, the power tranny is mostly likely on its way out. That's what my 900 did before it went for good (at least the power tranny). Blew the main fuse too.

 

[wixedmords]

Re: MY 900 is blowing fuses

You're going to need a set of extra tubes for troubleshooting purposes RA.

Try putting the proper fuse in the amp RA, then turn the amp on without any power tubes in the amp. If that blows the fuse you may have another issue, if it doesn't blow a fuse you may have a bad tube.

Also, "new tubes" doesn't mean one isn't having an issue.

Good luck.

 

[Reckless Abandon]

Re: MY 900 is blowing fuses

thanks everybody. My depression is setting in. I was worried getting a 900 since i had heard they have issues. If it was the new tubes it sucks since I only did it becuase I had not changed them sicne I bought the anmp in March. Where can I find the correct fuse? Lowes does not stock what I need and out hardware store suck.

So Erik you MKIII is shot? Good tone from it on your site.

 

[ErikH]

Re: MY 900 is blowing fuses

No, not shot as in totally dead. It just needs a power tranny. Once I get that in there with some new tubes it'll be fine. I'm going to have the output tranny checked out too just to be safe. It's a great amp with great tone and worth fixing, IMO.