Amp blowing? Amp problem

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  • thebreezethebreeze Frets: 2797
    ICBM said:
    thebreeze said:
    Sorry @ICBM quite right, we just crossed - there's more detail above but say if you need more.
    :)

    OK, so it is valve rectified - the 5AR4/GZ34, which will usually be at the end nearest the power cable/socket. There is a reasonable chance that this valve has failed, and the burning smell was coming from the base of the valve, rather than the socket. A short in the rectifier can blow the fuse even before the valves have warmed up.

    What to do is remove the rectifier valve, replace the fuse - you should be able to get the correct value on Ebay if you don't have one, you only need a couple - and power up again. If the fuse blows again with no rectifier in, it's a definite tech job.

    If it doesn't, it's probably worth buying a new rectifier valve (spares are useful anyway, and these aren't too expensive) and try again - make sure the amp is on standby when you power up. If it now blows immediately it's still a tech job. If it works until you switch from standby to on, it needs further investigation - there's probably enough to be going on with here!
    Okay, brief update (@bertie). ; I removed the GZ34 and replaced the fuse with a new one.  Blew immediately with a bit more of a bang this time and there were traces of smoke too.  I'll take it to a tech at some stage and let you know the upshot.  It's a shame as its the most amazing sounding amp and always behaved impeccably.  No idea why it's so suddenly being really weird?
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  • bertiebertie Frets: 13564
    thanks @thebreeze ; -   doesnt sound so good,  but good luck !!  


    just because you don't, doesn't mean you can't
     just because you do, doesn't mean you should.
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  • thebreezethebreeze Frets: 2797
    bertie said:
    thanks @thebreeze ; -   doesnt sound so good,  but good luck !!  


    Cheers man, its a bummer for sure.
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  • ICBMICBM Frets: 71960
    thebreeze said:

    Okay, brief update (@bertie). ; I removed the GZ34 and replaced the fuse with a new one.  Blew immediately with a bit more of a bang this time and there were traces of smoke too.  I'll take it to a tech at some stage and let you know the upshot.  It's a shame as its the most amazing sounding amp and always behaved impeccably.  No idea why it's so suddenly being really weird?
    Unfortunately that's potentially really quite serious. If you're lucky it might be the rectifier valve base - they can sometimes arc and carbonise, although in an amp like this I would probably expect it to be a ceramic one, which are almost immune to that - but if you're unlucky it could be the power transformer.

    Sometimes things just fail. They shouldn't, but they do...

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • thebreezethebreeze Frets: 2797
    ICBM said:
    thebreeze said:

    Okay, brief update (@bertie). ; I removed the GZ34 and replaced the fuse with a new one.  Blew immediately with a bit more of a bang this time and there were traces of smoke too.  I'll take it to a tech at some stage and let you know the upshot.  It's a shame as its the most amazing sounding amp and always behaved impeccably.  No idea why it's so suddenly being really weird?
    Unfortunately that's potentially really quite serious. If you're lucky it might be the rectifier valve base - they can sometimes arc and carbonise, although in an amp like this I would probably expect it to be a ceramic one, which are almost immune to that - but if you're unlucky it could be the power transformer.

    Sometimes things just fail. They shouldn't, but they do...
    Thank you for all your help.  Yes, it's getting on a bit I suppose.  The answer is don't stop using your amp!!
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