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Post by samdjr74 on Nov 8, 2022 16:02:27 GMT -7
Hello all,
The other day I turned my Dr Z on and took it out of standby when I noticed that the power light was off. After a quick troubleshooting session, I found the fuse blown. I replaced it and the amp played fine. A couple days went by, started playing it again, no problem. I was finishing up and put the amp into standby. As soon as I did, the power light went out, I blew another fuse. I'm sure I'll need to bring this into the tech, but any ideas would be greatly appreciated. The amp had the stock fuse (I assume, 1 A 250V) and when it blew, the only thing I had was a 4A 250V. I was planning on picking up a new fuse this weekend of the correct value, but it seems, I have more than a fuse issue.
Thank you, Sam
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Post by Chilly Gibbons (Todd T.) on Nov 8, 2022 16:43:52 GMT -7
Yes, almost always the power tube. Please don’t use the 4A fuse! Get another power tube, should solve your issues. It’s likely arcing over or shorting inside and blowing the fuse. Might also be the rectifier tube, but I’d start with the power tube.
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Post by purpletele on Nov 8, 2022 17:19:44 GMT -7
samdjr74,
Please make sure that you have the specified Rectifier or an NOS version. The Maz series has a voltage surge at start up and the Rectifier needs to be able to handle the surge.
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Post by samdjr74 on Nov 10, 2022 8:51:32 GMT -7
Hello all,
I'm running some tests today. Here's the results so far.
1. Removed all tubes, installed new 1A fuse, turned on Amp power switch then went from Standby to On, then turned Amp to Standby and turned off power, fuse didn't blow 2. Installed Rectifier tube, turned on Amp power switch then went from Standby to On, then turned Amp to Standby and turned off power, fuse didn't blow. I didn't notice any arching or red plating 3. Installed Rectifier tube and power tube, turned on Amp power switch then went from Standby to On, then turned Amp to Standby and turned off power, fuse didn't blow. I didn't notice any arching or red plating 4. Installed Rectifier tube, power tube and all preamp tubes, turned on Amp power switch then went from Standby to On, as soon as I took it off standby, the fuse blew. I didn't see any arching or red plating 5. Installed new 1A fuse, turned on Standby, then power, fuse blew immediately.
Now, the power tube seemed to be glowing very brightly, which could be my imagination but I'll make a quick video later today to show what I mean.
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Post by samdjr74 on Nov 10, 2022 9:25:47 GMT -7
Ok, quick update, I replaced the EL84 with a JJ EL 844 (only one I had available) and the amp seems to be fine now. So, I'm guessing my stock tube is bad (passed a tube test but I know, can't trust that)
Thanks all
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