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Post by obm on Nov 10, 2023 15:14:16 GMT -7
Hi all!
Long time no talk... My maz 18 nr blew its fuse twice in a row. Anything else I should check? Or the fuse was cheap or something?
Thanks in advance!
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Post by Chilly Gibbons (Todd T.) on Nov 10, 2023 15:17:05 GMT -7
Probably a bad output tube that is either shorted inside or arcing over real bad.
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Post by obm on Nov 10, 2023 15:46:22 GMT -7
Probably a bad output tube that is either shorted inside or arcing over real bad. Thanks for the quick reply! So first step would be to check the output tube? Any signs on it I should check that it is the output tube? Or I buy replacement, change the fuse, and then see if it works?
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Post by headshrinker (Marc) on Nov 10, 2023 15:54:49 GMT -7
My way. Pull all of the tubes. Mark their position so they go back the same way. Put in new fuse and rectifier tube. Turn it on and see if it blows. Yes, you found the problem. No, leave it in and put in the two power tubes, turn it on and see what happens. Yes, the problem is them, No, move on to the preamp tubes one tube at a time. My guess you will find it's one of those first three. Usually, but not always, when preamp tubes go, they don't take out the fuse.
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Post by Jaguarguy (Mike) on Nov 10, 2023 16:38:15 GMT -7
Here's the Doc's trouble shooting video - pretty much what Marc said.
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Post by purpletele on Nov 10, 2023 19:09:38 GMT -7
I would recommend installing the recommended Rectifier tube or an NOS Rectifier.
I had a blown fuse issue, and I went down a rabbit hole. The Maz series needs a strong rectifier!
Brian V
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Post by obm on Nov 13, 2023 12:10:05 GMT -7
Thanks all! My local electronic shop (that sells 2amp fuses) is closed on Sunday and Monday... I'll be at it tomorrow.
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Post by The Bad Poodle Experience on Nov 13, 2023 12:52:36 GMT -7
Thanks all! My local electronic shop (that sells 2amp fuses) is closed on Sunday and Monday... I'll be at it tomorrow. here's another issue no one mentioned. i had a fuse blowing situation with my Maz 38 and ended up being a cracked power tube socket. inexpensive fix down at the local repair shop.
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Post by obm on Nov 15, 2023 19:38:11 GMT -7
Thanks for the info! I've followed Marc and Mr Dr Z's tutorial. Unfortunately I get to the end where the fuse doesn't blow up again. I tested every single tubes and nothing.
- Is there an amount of time it should stay on before I go on to the next one? I kept it powered on for about a minute.
One thing I noticed when the (2nd) fuse blew. My volume knob was completely rolled to the right (full). Could that have caused a blown fuse?
It's an older model with 2 fuses. The HT one is fine. It's the 2A that blew.
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Post by obm on Nov 15, 2023 19:39:07 GMT -7
Should I simply plug it in tomorrow, and play (guitar) with it. If it holds then I go on with my life? Lol!
I really appreciate the support!
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Post by purpletele on Nov 15, 2023 21:29:30 GMT -7
Should I simply plug it in tomorrow, and play (guitar) with it. If it holds then I go on with my life? Lol! I really appreciate the support! What Rectifier Tube do you have in the amp? Did you swap the rectifier when you rolled the other tubes? If so, what did you swap it with?
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Post by obm on Nov 16, 2023 6:09:19 GMT -7
Should I simply plug it in tomorrow, and play (guitar) with it. If it holds then I go on with my life? Lol! I really appreciate the support! What Rectifier Tube do you have in the amp? Did you swap the rectifier when you rolled the other tubes? If so, what did you swap it with? I actually did exactly like shown on the video. Replaced the blown fuse. Removed ALL tubes. Turned it on. Fuse didn't blow. Then put the rectifier tube in. Turned it on, stand by on. Fuse didn't blow. And so on all the way to the last tube. Amp stayed on. Fuse didn't blow like it did twice when I wrote this message thread last week. I didn't replace the rectifier tube. It's a JJ GZ34 (going with numbers off the top of my head, it's the exact recommended by Z)
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Post by purpletele on Nov 16, 2023 8:10:22 GMT -7
What Rectifier Tube do you have in the amp? Did you swap the rectifier when you rolled the other tubes? If so, what did you swap it with? I actually did exactly like shown on the video. Replaced the blown fuse. Removed ALL tubes. Turned it on. Fuse didn't blow. Then put the rectifier tube in. Turned it on, stand by on. Fuse didn't blow. And so on all the way to the last tube. Amp stayed on. Fuse didn't blow like it did twice when I wrote this message thread last week. I didn't replace the rectifier tube. It's a JJ GZ34 (going with numbers off the top of my head, it's the exact recommended by Z) If it's working, then maybe you had a bad power tube which will certainly blow a fuse. If the fuse blows again, I would pull the JJ GZ34 and replace it with an NOS GZ34 or the Sovtek 5AR5.
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Post by obm on Nov 16, 2023 8:23:10 GMT -7
Ok, so next step, if the fuse blows again, buy an NOS GZ34 or Sovtek 5AR5?
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Post by frankie on Nov 16, 2023 9:54:10 GMT -7
Ok, so next step, if the fuse blows again, buy an NOS GZ34 or Sovtek 5AR5? Here's the next step. With the lights off or dimmed really low, turn the amp around and play and watching what is happens to the power tubes and rectifier in particular. Watch for arching (lightning in the bottles) or red plating (cherry red glowing on the gray plates of the power tube). Red plating can take some time (up to 3-4 minutes) before it really takes out a fuse. Replace the power tubes (both of them), if you see any indication of this. If you play for 5-10 minutes and nothing happens, power down, then power on, and flip the amp in and out of standby repeatedly 10-20 times. Toggling the high voltage like this can stress a faulty rectifier to the point where it blows a fuse. If it blows a fuse during this test, then replace the rectifier. Don't waste your money on NOS rectifiers. For the price of one of them, you can buy a half dozen of back up current production rectifiers.
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Post by obm on Nov 16, 2023 10:37:38 GMT -7
Ok, so next step, if the fuse blows again, buy an NOS GZ34 or Sovtek 5AR5? Here's the next step. With the lights off or dimmed really low, turn the amp around and play and watching what is happens to the power tubes and rectifier in particular. Watch for arching (lightning in the bottles) or red plating (cherry red glowing on the gray plates of the power tube). Red plating can take some time (up to 3-4 minutes) before it really takes out a fuse. Replace the power tubes (both of them), if you see any indication of this. If you play for 5-10 minutes and nothing happens, power down, then power on, and flip the amp in and out of standby repeatedly 10-20 times. Toggling the high voltage like this can stress a faulty rectifier to the point where it blows a fuse. If it blows a fuse during this test, then replace the rectifier. Don't waste your money on NOS rectifiers. For the price of one of them, you can buy a half dozen of back up current production rectifiers. I appreciate your return! - Didn't notice any lightning - The power tubes seems to be glowing 'normally' - Did the 10 to 20 in and out of stand by. The rectifier held it. Might be at the end of tubes life. I'll play with it until it happens again. I noticed I have a Sovtek Gz34 at home and plenty of power tubes. I'll be able swap if needs be.
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Post by obm on Nov 20, 2023 8:29:57 GMT -7
Still nothing after a couple of hours playing... Only thing I've noticed is I hear a crackling noise out of the tubes after I turn it off. A physical sound. But it's only because I am searching for something that I hear it.
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Post by frankie on Nov 21, 2023 9:49:32 GMT -7
Still nothing after a couple of hours playing... Only thing I've noticed is I hear a crackling noise out of the tubes after I turn it off. A physical sound. But it's only because I am searching for something that I hear it. When you turn the amp off, you will still hear sound (for about 5-10 seconds depending on the volume you play), as you are hearing the filter capacitors discharge their voltage. This is normal. Is it possible you had a different value of fuse in before? Strange for it to happen twice, now nothing after hours of playing.
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Post by obm on Nov 24, 2023 20:32:04 GMT -7
Don't think the value was different. 2 amps fuse
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Post by frankie on Nov 29, 2023 11:03:47 GMT -7
Don't think the value was different. 2 amps fuse 2A fast blow would be in the older pre-2011 amps. 1.5A slow blow is what we currently use. Roughly the equivalent. If you can recall what you were doing/playing/under what conditions the fuse blew the first two times, that might help get a clue. If there was any noise associated with it blowing too. I'm glad it hasn't happened again, but I'm curious because fuses most often indicators of other problems.
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Post by purpletele on Nov 29, 2023 22:48:49 GMT -7
I mis-read a previous post, I thought you had actually changed the power tubes to new tubes.
Interesting events, but most likely a simple explanation. Maybe re-installing all of the tubes enabled a bad pin connection?
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Post by walt on Dec 2, 2023 16:02:35 GMT -7
I love threads like these,and the AMA's.I know very little about tube amp's,and appreciate the knowledge
Hope your amp is all good OBM.
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Post by obm on Dec 12, 2023 20:52:52 GMT -7
I love threads like these,and the AMA's.I know very little about tube amp's,and appreciate the knowledge Hope your amp is all good OBM. Yep! No issues so far!
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