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Thread: Troubleshooting a DRRI - major static when switching from standby to on. Blows fuse.

  1. #1

    Troubleshooting a DRRI - major static when switching from standby to on. Blows fuse.

    I'm hoping to troubleshoot this amp for my son. Fender Deluxe Reverb Reissue in very nice condition cosmetically. My son was given this, as it was not working.

    The first thing I noticed was that the speaker's fiber (cardboard?) wire connector tab was popped off its rivet. That may have meant issues with speaker noise and malfunction. I happened to have a replacement speaker and put that in. Fingers crossed, I was hoping I was good to go, but...

    Powered up, switched standby switch to ON and NOISE! Static, scratchy not-good-sounding noise (all controls knobs at 1). Switched off using either power or standby. I did this a few times. At one point, I removed the electronics assembly and used deoxy to clean the control pots, thinking it might be dirty pots. Tried again and got the same noise. I then, meaning to switch standby off, inadvertently switched power off first, and then the fuse blew.

    I read up on troubleshooting this issue and saw that I could insert tubes one by one, powering down between each tube insertion, to see if a bad tube might be causing these issues. I went another route: inserted preamp tubes and powered up, but did not switch standby to ON. No issues. I then put in the power tubes and did the same: power on, but kept in standby; again, no issues. I then, finally, installed the rectifier tube and powered up - no issues.

    Note that I did not switch the standby switch to ON during any of this. I thought the fuse might blow with all tubes in, power on and standby in standby mode (as noted, it didn't).

    Where do I go from here? I guess I'm afraid to switch standby to ON before knowing more about whether or not I'm heading in the right direction. Time for a tech? This was a gift (albeit a "broken" one), and I wasn't prepared to dump money into it without first seeing if I could DIY.

    Ian SF Bay Area

  2. #2
    Forum Member CoyotesGator's Avatar
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    Re: Troubleshooting a DRRI - major static when switching from standby to on. Blows fu

    Yeah.

    pull all tubes EXCEPT rectifier.

    power up and take off of standby.
    What happend?
    Who let the magic smoke out?

  3. #3

    Re: Troubleshooting a DRRI - major static when switching from standby to on. Blows fu

    Thanks for the input! So, if I understand right, because it is often the rectifier tube that is the culprit, by having all tubes, except the rectifier, installed, the power on, then the standby on, I might at least be able to zero in on the rectifier as the issue, if, with the above done, the amp is quietly humming along.

    Of course, this would be ideal - having to source and replace the one tube, rather than scatter-gunning the issue with a complete new set of tubes.

    Thanks again, I’ll post my results!

    Ian SF Bay Area

  4. #4

    Re: Troubleshooting a DRRI - major static when switching from standby to on. Blows fu

    I did just power up with the rectifier removed and the Standby in the ON position: no scary noises!

    Am I to assume that the rectifier is the issue?

    My next step appears to be fitting a new rectifier tube and double checking performance. If all seems good, I guess that's that and I'm good to go (or my son is, as it's his amp). I'll report back if anything is amiss.

    I then hope to A/B the Jensen P12N I put in as a replacement, with the by-then fixed, Fender Eminence speaker original to the amp.

    I should note that this amp appears to be from 1990 to 1993, or so, according to its serial number. All tubes I believe to be original to the amp, as they are all Fender branded.

    Ian SF Bay Area

  5. #5
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    Re: Troubleshooting a DRRI - major static when switching from standby to on. Blows fu

    You will get no noises with the rectifier removed, as there is no B+ voltage. I would sub another rectifier, and retest, if the problem returns, there is a problem in the HV section.

  6. #6

    Re: Troubleshooting a DRRI - major static when switching from standby to on. Blows fu

    Thanks for that info! HV, I take it, means High voltage?

    I’m thinking that, yes, I’ll replace the rectifier tube and go from there.

    Learning new things everyday!

    Ian SF Bay Area

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