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Post by cbertram75 on Mar 13, 2022 14:03:56 GMT -7
I recently acquired a Maz 18 NR (about a week ago). Everything has been working great- until Friday. I switched it on and no sound. I replaced the speaker and the tubes (with a matched set I acquired from the tube store) and it was working perfectly (again until this past Friday). I’m hoping someone can help get me moving in the right direction toward fixing it. Here is a quick summary of what the issue is and what I’ve done so far:
1) replaced speaker and tubes (and it worked perfectly after replacement… until it didn’t) 2) checked the fuse from the back panel with a multimeter- it’s good 3) the only tube that will light up/heat up is the 5AR4 rectifier, the other tubes will not light up or heat up 4) I tried re-seating all of the tubes- that didn’t work 5) I tried swapping the new tubes out with the old tubes- that didn’t work either.
Any suggestions? Is there another fuse somewhere that may need to be replaced? Thanks for any help!
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Post by DRZ on Mar 13, 2022 15:59:52 GMT -7
Strange sequence of failures on your used MAZ NR. Seems maybe a tube failed, you swapped them all out and it work for a week. Now only the Rectifier is lite up. The rectifier has a separate 5 V filament supply directly connected to its socket. The other 5 tubes get a 6.3 V filament supply from separate winding . The 6.3 V feeds the indicator lamp first, if that is lite up the transformer is good ( that is if it is new enough to have a Jeweled lens Fender style ). From the indicator lamp the 6.3 V is daisy changed to each of the 5 tubes. So it would seem the problem is in the connection from the lamp holder to the first EL 84. Kind of hard to believe that would fail , but you will need a qualified tech to sus that out I feel.
DR.Z
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Post by cbertram75 on Mar 13, 2022 17:27:28 GMT -7
Thanks, Dr. Z! Yes, it does have a jewel (manufactured 2/12), and yes it still lights up. The previous tubes were working fine when I brought it home... figured it probably wouldn't hurt to retube it. So I did. Hopefully I didn't cause the issue. I'm in Dayton, OH- are there are any authorized repair shops you might recommend in my area?
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Post by DRZ on Mar 13, 2022 17:34:32 GMT -7
Not sure about a tech in Dayton. Try installing the original EL 84's back in first.
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Post by Chilly Gibbons (Todd T.) on Mar 13, 2022 17:35:15 GMT -7
There’s a really, really good one up I’m Maple Heights. It’s called Dr…..something…… 😁
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Post by cbertram75 on Mar 13, 2022 17:57:10 GMT -7
I did try reinstalling the original el84s. I tried to follow the trouble shooting guide first. No dice, unfortunately. Looks like I may have to bring her in. I appreciate the help.
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cmrharvey
Full Member
Greater Atlanta
Posts: 103
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Post by cmrharvey on Mar 14, 2022 6:39:45 GMT -7
There should be a second fuse on your NR. Depending on year. Mine is a 2011 model and has 2 different fuses. There are others on this forum that have better computer skills who can post pics and guide you to Don in repairs, and he can guide you as well. Hope you can find the culprit on this. Very frustrating, I know.
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