Impedance related question, need help.

[7 Stringer]

OK, i`ve just blown a fuse on my 5153, replaced it, blown again. I don`t know what the particular fuse does, it`s a small 1A 250v fuse located inside the amp. When it blows, there`s no sound, everything stays on but no sound. I`m guessing it`s a protection on the output tranny???

Here`s my setup and maybe i`m doing it wrong?

5153@ 4 ohm impedance.
out to VHT 16ohm cab
out to Mills 8ohm cab > ext.speaker out to ISP sub @ 8ohm setting.

Is this hooked up properly? I` just plugged my Framus Cobra and everything seems fine.

I did blow the same fuse on the 5153 about 1 1/2 years ago, replaced it and everything fine after that.

The ohm thing confuses me a bit. Any help would be really appreciated.

Thanks,

Chris

 

[JTyson]

I dont think its the impedance mismatch that is blowing the fuse. I'm not familiar enough with the pvy to know what it might be beyond that. Do all the tubes appear to be ok? You could easily just connect the 16 ohm cab with the amp set to 16ohms and leave the rest unhooked to verify. See if any tubes are glowing more or less than the others. That would be a starting point

 

[7 Stringer]

I dont think its the impedance mismatch that is blowing the fuse. I'm not familiar enough with the pvy to know what it might be beyond that. Do all the tubes appear to be ok? You could easily just connect the 16 ohm cab with the amp set to 16ohms and leave the rest unhooked to verify. See if any tubes are glowing more or less than the others. That would be a starting point

It`s an EVH 5153, i wanted to do that but i don`t have anymore fuses

Tubes seem OK, power that is, didn`t check the pre ones, they all have covers. I`ll have to get me more fuses.

Thanks for your input.

Chris

 

[tubebury51]

The power tubes could still look "OK" and have fliaments heated, but still cause a blown fuse. It's worth swapping them out with another good set to be sure. Does it blow when you set the head at 16ohms and just run one 16 ohm load?

 

[LP Freak]

As long as the cabinet's ohms is rated higher than the amp's, you'll be fine. You'll just loose a little volume. A blown fuse is usually a good indication of a bad power tube.

 

[lolzgreg]

I agree that it's probably the t00bz.

 

[7 Stringer]

The power tubes could still look "OK" and have fliaments heated, but still cause a blown fuse. It's worth swapping them out with another good set to be sure. Does it blow when you set the head at 16ohms and just run one 16 ohm load?

I don`t have any more fuse to test it out, i`ll get some next week(i`m leaving on vacation tomorrow morning).

I gotta go but thanks for all your help guys, i`ll report when i`m back.

Chris

 

[thunda]

If you're blowing internal fuses, as previously stated you have a power tube going south...

 

[7 Stringer]

OK, changed the fuse, tubes, biased a little hotter, not by much cause any higher and it looses punch.

So far so good.

I didn`t use my GE-7 in the loop, could that cause an overload in the FX return and is that fuse protected?

Cause the last time the fuse blew i had the GE-7 with a bass and level boost.

Chris

 

[tubebury51]

OK, changed the fuse, tubes, biased a little hotter, not by much cause any higher and it looses punch.

So far so good.

I didn`t use my GE-7 in the loop, could that cause an overload in the FX return and is that fuse protected?

Cause the last time the fuse blew i had the GE-7 with a bass and level boost.

Chris

I don't think the EQ pdl in the loop would have an effect UNLESS you are plugging and unplugging the loop cable connections WHILE the STAND BY switch is ON.... I have had that happen a few times on an amp I used to have.... Good luck!