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Post by Deleted on May 16, 2015 14:38:59 GMT -7
Getting some low frequency hum from my EZG--nothing plugged in, gets louder as you roll the volumes up. Power tubes, or something worse?
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Post by DRZ on May 16, 2015 16:38:15 GMT -7
Try the troubleshooting list from our website. I would say 90% of the time it's a bad tube, just need to find it and replace it. The TS list will help.
Z
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Post by Deleted on May 16, 2015 18:33:50 GMT -7
Thanks, Doc!
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Post by Deleted on May 16, 2015 21:10:52 GMT -7
Hey I had the same problem a little while ago- it wasnt tubes. It was that the reverb wasnt plugged in properly
theres 2 cables that plug into the chassis form the reverb tank. Make sure their plugged in all the way. Thats what solved my problem with that exact issue- a bass feedback that got really bad as you turned up the volume.
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Post by Deleted on May 16, 2015 21:30:39 GMT -7
Will give it a shot--thanks!
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Post by Deleted on May 17, 2015 8:10:21 GMT -7
Turns out both 12AX7s were sketchy. Replaced them with new and no more hum. My home amp repair skills pretty much begin and end with tube-swapping, so I'm glad it worked out. Realized I've still got the original power tubes from two years ago in there (GTs!), and have ordered a replacement set. Will take it to local shop for biasing when they arrive.
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Post by Deleted on May 17, 2015 8:40:22 GMT -7
Oops! Spoke too soon. Hum is gone (yay!), but now I'm getting a sound like wind from the reverb--turn the dwell all the way down and it disappears, gets louder as you turn it up.
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Post by z4me on May 17, 2015 10:27:10 GMT -7
Jon, did you check the wires from the reverb tank to ensure they were seated properly as PT60p mentioned? Maybe unplug and plug them back in a few times, say 10, to eliminate dust or slight corrosion issues with those connections. Of course there may be more info in the TS guide per Doc's comments.
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Post by Deleted on May 17, 2015 13:26:26 GMT -7
I did, but will open her up and try again. It may be that the one of the 12AX7s I put in as replacements was bad, too. Or maybe something's not quite seated right. Amp sounds great otherwise, though.
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Post by z4me on May 17, 2015 14:42:22 GMT -7
A good rule of thumb with tube swapping is to use electronic contact cleaner, spray it on the tube pins and then work the tube in a out of the socket a few times to clean tube pins and socket contacts. In your case with new tubes with clean pins, you may have some dirty or a little bit of corrosion on some socket contacts. Worth a try anyway.
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Post by BritInvasion on May 17, 2015 16:42:39 GMT -7
Chassis bolts nice 'n tight?
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Post by Deleted on May 18, 2015 6:32:40 GMT -7
Which are the tubes for the reverb in this critter, anyways?
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Post by DRZ on May 18, 2015 7:37:29 GMT -7
Which are the tubes for the reverb in this critter, anyways? V3= 12AT7 usually a JJ ECC 81 S V4= 12AX7 usually a Sovtek 12AX7 WB
Check reverb cables as PV60 stated.
Z
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Post by Deleted on May 18, 2015 7:51:09 GMT -7
Thanks, Doc. Swapped V4; still getting a loud rushing sound. Don't have a 12AT7 on hand so will have to wait til my Tube Depot order gets here.
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Post by Deleted on May 18, 2015 11:48:32 GMT -7
Checked reverb cables, etc., still getting noise. Frustrating--fixed the hum but somehow created a different issue in the process.
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Post by headshrinker (Marc) on May 18, 2015 11:51:46 GMT -7
You can sub a 12AX7 for the 12AT. If the whooshing goes away, you will know it's the 12AT. If it is still there, it's likely not the 12AT. You may even like the 12AX in there.
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Post by Deleted on May 18, 2015 12:57:14 GMT -7
Will give it a shot--thanks, Marc! How's things in The Plains?
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Post by Deleted on May 18, 2015 14:10:28 GMT -7
The mystery is solv-ed, as Inspector Clouseau used to say. Swapped V2 with an old Sovtek 12AX7 I had lying around and no more rushing sound. Also, no more hum. Trying to remember if I left her sitting in standby overnight or what--something's done a number on my preamp tubes, but not sure what that something was other than the fact that they're a couple of years old. In any case, it's resolved (touch wood), and this episode has been a reminder to take her in and have those power tubes replaced and re-biased. Thanks Doc, Marc and all for your help!
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