Dual Rec - How often to YOU have to change the fuse.

[satanicWarmaster]

picked up a used dual rec a while back,
seemed to work with no issues, untill say the first time ive used it for 45 mins or so at jamming level volumes.
then just shut off on me. checked the fuse - it was blown.

replaced it, and it blew again, after about 3-4 hours of usage. (through out a 2 week period or so)
worked fine after i replaced it again.

was wondering how often anyone else notices their fuse blows.
Im thinking this is too often? maybe something to do with the amp is drawing too much current when i turn it up?

 

[b0nkersx]

Yeah, that is abnormal. You might have faulty rectifier or power tubes.

 

[mikey383]

I have only changed my fuse once in 3.5 years of owning my Dual. That was because I found a 30 amp fuse in it after owning it for 2.5 years.

I also found a burnt screen resistor, which tells me the previous owner blew a tube and just kept replacing fuses until it burnt the resistor. He finally quit when he got to 30 amps. And the fuse had seen massive amounts of heat, as it was warped.

Let me ask you this: What tubes do you have in your amp? It sounds to me as if they were replaced with ones that aren't within the bias range for Mesa amps, and they are drawing too much current when they get to max temp, or you have a tube that is shorting when it gets hot. Either way, it's probably time to replace your power tubes.

 

[satanicWarmaster]

not exactly sure on the tubes, some brand 6L6's - they were replaced from what i was told from the seller,

what would you recommend as a replacement to start at

 

[MrMarkIII]

Yep, definitely a malf. Fuses are not generally considered parts which require changing on any kind of regular basis, and when they do blow it's because the fuse just saved a much more expensive part from frying.
You need a set of spare power bottles anyway, but if the fuse still blows after replacing them, time for the shop.
Don't let the last words you ever read be: "No User Serviceable Parts Inside" :lol:

 

[fluff191]

I would change your power tubes with properly rated ones to start.

My amp did the same thing after I initially installed an adjustable Bias.

It would blow the fuse as soon as I cranked it.

 

[Silverwulf]

You should never have to replace the fuse unless you have an issue. It's just there as a safeguard for other, more expensive and important parts. If you're blowing fuses, you likely have a power tube going bad, so start there.

 

[satanicWarmaster]

have never replaced tubes before, also i dont know all to much about the dual rec, besides what ive been reading online and consulting the manual.

but thinking to just replace both power and rectifier tubes with: JJ 6L6GC's / JJ 5U4GB's
good idea? good start? or no.

 

[ccwhiskey]

been reading alot about mesa tubes online and just read the manual a few times . it says to use the mesa tubes because they are made for the amp ,that's what il be putting in when the time comes ....

 

[domct203]

I recommend you start fresh with all Mesa tubes. This is your first Recto so I would start with it the way Mesa intended.

Dom

 

[droptrd]

are you using the tuberectifier setting or the diode setting? If you are using thr diode setting, you shouldnt have to bother with the rectifier tubes.

Also, one of my DR's was blowing fuses. I replaced the preamp tubes and the prob went away.

 

[jtb226]

If you are using thr diode setting, you shouldnt have to bother with the rectifier tubes.

Not true. My DR was doing the same thing as the OP the other year. A change of the rectifier tubes and the problem hasn't come back since.

 

[mrodr008]

I bought a JJ RK tube set on ebay. Changed all tubes, soon after I blew the fuse. Replaced it.. then blew the fuse again. Replaced it. Then I started hearing some noise/static which got very annoying and I finally did some further troubleshooting and found one of the JJ EL34 went bad. Replaced it with one of the old Mesa EL34. Running smooth now. So my RKII is running all JJ pre and power tubes except for one Mesa tube now. Seemed to fix all the problems.

 

[mikey383]

I bought a JJ RK tube set on ebay. Changed all tubes, soon after I blew the fuse. Replaced it.. then blew the fuse again. Replaced it. Then I started hearing some noise/static which got very annoying and I finally did some further troubleshooting and found one of the JJ EL34 went bad. Replaced it with one of the old Mesa EL34. Running smooth now. So my RKII is running all JJ pre and power tubes except for one Mesa tube now. Seemed to fix all the problems.

You should replace the other tube as well. They should operate in pairs.

 

[litesnsirens]

If you are using thr diode setting, you shouldnt have to bother with the rectifier tubes.

Not true. My DR was doing the same thing as the OP the other year. A change of the rectifier tubes and the problem hasn't come back since.

How could that not be true. You have supported his argument. Indeed he is saying if there is a problem with the recitifer tubes and you set to diodes, then you by-pass the recitifier tubes and therefore won't have a problem with the fuse. If, however you want to use the tube recitifiers you are going to have to change them.. which is the most likely reason for blowing fuses. droptrd is just sayiing that's a quick temporary fix if you are blowing fuses, just switch to diode mode until you can replace the recitfier tubes.

 

[mikey383]

If you are using thr diode setting, you shouldnt have to bother with the rectifier tubes.

Not true. My DR was doing the same thing as the OP the other year. A change of the rectifier tubes and the problem hasn't come back since.

How could that not be true. You have supported his argument. Indeed he is saying if there is a problem with the recitifer tubes and you set to diodes, then you by-pass the recitifier tubes and therefore won't have a problem with the fuse. If, however you want to use the tube recitifiers you are going to have to change them.. which is the most likely reason for blowing fuses. droptrd is just sayiing that's a quick temporary fix if you are blowing fuses, just switch to diode mode until you can replace the recitfier tubes.

If the rectifier tube heater is shorted, then switching to diodes will not cure the blowing fuse problem. Even though you're using diodes, the rectifier tubes still have power to them and their heaters.

 

[mrodr008]

I bought a JJ RK tube set on ebay. Changed all tubes, soon after I blew the fuse. Replaced it.. then blew the fuse again. Replaced it. Then I started hearing some noise/static which got very annoying and I finally did some further troubleshooting and found one of the JJ EL34 went bad. Replaced it with one of the old Mesa EL34. Running smooth now. So my RKII is running all JJ pre and power tubes except for one Mesa tube now. Seemed to fix all the problems.

You should replace the other tube as well. They should operate in pairs.

I wondered about that. I had the ebay seller ship me a replacement tube. Thanks for the tip!

 

[litesnsirens]

fair enough mikey383. I was just going with what would be the first and most common problem which would be the tube. Had that happen to me when I had the Lonestar Special. Rectifier tube went, blew the fuse and then another before I figured out it wasnt' just the fuse. I called Mesa and he told me to put the amp in 30 watt mode and see if it works, which it did because in 30 watt mode it uses the silicon diode rectifier, 15 and 5 watts uses the rectifier tube. So of course I replaced the rectifier tube and got all 3 power modes back. He advised when fuses start to go that is the most likely culprit.