Odin
Full Member
Posts: 144
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Post by Odin on Dec 15, 2008 21:52:35 GMT -7
My Maz 38 Senior 2x10 combo came on and then immediately popped off, making a sickly little noise when it did. The 3/4A fuse is blown. I tried putting in a new 3/4A fuse but the amp is still dead.
I tried swapping out all of the preamp tubes, as the power tubes are nearly new. haven't tried swappign power tubes or rectifier yet.
I pulled the chassis and there are no obvious problems, all connections are good and components look intact.
Any ideas if it isn't the power tubes or rectifier?
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Post by benttop (Steve) on Dec 15, 2008 21:56:34 GMT -7
Usually power tubes for that fuse. New or not, they can have infant mortality issues and can go south right quick. I've had the same thing happen here with other amps. You have nothing to lose by getting another set and trying it - if the problem persists, at least you have a decent backup set.
Next step would be rectifier, but usually the larger fuse blows when the recto shorts out.
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Post by cementedman on Dec 15, 2008 22:12:50 GMT -7
hey odin, did you do anything unusual to the amp before?, was it stock, did anyone play with the tubes etc? i had a 38 combo, i sold it to my friend in kC, and after a while it shorted out,, it so happened that the main solder joint shorted out,, the solder broke,, very easy fix, if you can solder, i had a big time harry joyce head that this happened to. this is just the kind of things that happens to point to point wired stuff. i would bet this is not a major deal... i have a friend in tulsa ok that fixes this kinda stuff for a bench charge, 20 to 30 bucks,, maybe more down there..
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Odin
Full Member
Posts: 144
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Post by Odin on Dec 15, 2008 22:54:38 GMT -7
OK, so I swapped the power tubes and the same thing was happening.
I swapped the 5AR4 with the rectifier from my Maz 18 head and that fixed it. The last thing I would suspect of crapping out is a rectifier tube...I have rectifier tubes still working that are older than me.
The only spare rectifier tube I have around the house is an old GE 5U4GB...can I use that in a Maz 18 or Maz 38, or is that a no-no?
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Post by benttop (Steve) on Dec 15, 2008 23:17:57 GMT -7
Recto eh? Well at least it's not a more serious problem. Not sure on your proposed replacement though...
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Post by myles on Dec 18, 2008 15:22:47 GMT -7
OK, so I swapped the power tubes and the same thing was happening. I swapped the 5AR4 with the rectifier from my Maz 18 head and that fixed it. The last thing I would suspect of crapping out is a rectifier tube...I have rectifier tubes still working that are older than me. The only spare rectifier tube I have around the house is an old GE 5U4GB...can I use that in a Maz 18 or Maz 38, or is that a no-no? When a fuse blows that is the first thing you should suspect, not the last. Second thing is a shorted power tube.
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captain38
Full Member
I followed you big river...
Posts: 198
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Post by captain38 on Jan 23, 2009 12:55:29 GMT -7
How often do y'all have to replace rectifier tubes?....I believe I am on my 3rd or 4th one (over the course of about 5 years). This seems to be a little too often if you ask me. Not saying anything bad about my Z, just wondering what might cause this to happen this often.
I also have a solder joint that keeps breaking right by that same fuse. I have had this re-soldered about 4 or 5 times. Everytime it was by people that are very effecient with a solder gun...even including taking it to Z's staff one time. Any idea what causes this?...I am not twisting or bumping that joint at all...ever.
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Post by benttop (Steve) on Jan 23, 2009 14:10:29 GMT -7
My understanding is new manufacture rectifiers are not so reliable as NOS ones. I spent a considerable sum on some NOS Mullard rectifiers here and they have not failed me yet. Been running those for a couple years now, but who knows what that translates to in hours and compared to your use? If you're buying new rectos every year, it's probably worth getting a NOS one that lasts ten years.
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Post by myles on Jan 23, 2009 14:35:51 GMT -7
My understanding is new manufacture rectifiers are not so reliable as NOS ones. I spent a considerable sum on some NOS Mullard rectifiers here and they have not failed me yet. Been running those for a couple years now, but who knows what that translates to in hours and compared to your use? If you're buying new rectos every year, it's probably worth getting a NOS one that lasts ten years. NOS rectifiers will last decades. New production rectifiers are a crap shoot and can fail without warning at any moment no matter what their age. If you do not have an NOS rectifier in you amp always carry a spare and make sure the spare works before you need it for at least 20 hours so you get rid of the infant mortality aspects and then only have to worry about the general unreliable general nature of the new production rectifier.
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Post by "Z" Steve on Jan 23, 2009 15:24:42 GMT -7
Odin. After my Maz blew it's rectifier tube I replaced it with a NOS from Mike at KCA, but I also picked up a Weber Copper Cap rectifier from Ted (about 22 bucks) as a spare as well - I keep it in my case with my guitar cords and misc. stuff just for insurance purposes.
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Deleted
Deleted Member
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Post by Deleted on Jan 23, 2009 21:16:04 GMT -7
Odin. After my Maz blew it's rectifier tube I replaced it with a NOS from Mike at KCA, but I also picked up a Weber Copper Cap rectifier from Ted (about 22 bucks) as a spare as well - I keep it in my case with my guitar cords and misc. stuff just for insurance purposes. That Weber Copper will make your amp run a little hotter won't it? Did you have to check the voltages to make sure you're safe?
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Post by "Z" Steve on Jan 24, 2009 12:28:00 GMT -7
I had emailed Ted about it being a good replacement and he made no mention of that. I know Myles has mentioned BW and a few other players using them while on an extended tour but never commented on that piece - that would be a good thing to know
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Post by benttop (Steve) on Jan 24, 2009 14:09:48 GMT -7
Dr. Z says don't use them on the 2-EL84 amps, but they are ok on the 4-EL84 amps.
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Post by "Z" Steve on Jan 24, 2009 16:41:00 GMT -7
Thanks for the clarification on that one Steve.
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Post by Curt on Jan 24, 2009 17:14:32 GMT -7
OK, so I swapped the power tubes and the same thing was happening. I swapped the 5AR4 with the rectifier from my Maz 18 head and that fixed it. The last thing I would suspect of crapping out is a rectifier tube...I have rectifier tubes still working that are older than me. The only spare rectifier tube I have around the house is an old [glow=red,2,300]GE 5U4GB.[/glow]..can I use that in a Maz 18 or Maz 38, or is that a no-no? you can use that rec in either MAZ, it will cut output a bit, you may or may not like what it does, but it is fine to run it in either amp.
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Post by myles on Jan 25, 2009 10:20:28 GMT -7
OK, so I swapped the power tubes and the same thing was happening. I swapped the 5AR4 with the rectifier from my Maz 18 head and that fixed it. The last thing I would suspect of crapping out is a rectifier tube...I have rectifier tubes still working that are older than me. The only spare rectifier tube I have around the house is an old [glow=red,2,300]GE 5U4GB.[/glow]..can I use that in a Maz 18 or Maz 38, or is that a no-no? you can use that rec in either MAZ, it will cut output a bit, you may or may not like what it does, but it is fine to run it in either amp. Don't take short cuts ... go get the proper rectifier.
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