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Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

Help with amp blowing fuses?

Discussion in 'Glowing Bottle Tube Amp Forum' started by Asmith, Nov 28, 2017.

  1. Asmith

    Asmith Friend of Leo's Ad Free Member

    Age:
    21
    Nov 27, 2014
    Morley, England
    Relatively new to the tube amp experience and so far I've enjoyed it until my AD30r cut out.

    To break it down it's blowing 2 fuses verified using a DMM,

    The HT fuse (500mA) and the mains fuse (2A), they are the correct value as stated on the chassis and I'm not going to use other fuses for obvious reasons.

    When turned on I get some noise out of the guitar for a very short time (during the tube warm-up period until the fuses blow, I'm using slow blows). I've only swapped the fuses once to see if the amp would blow them again the second time.

    From what I can tell the heater fuse must be going first and then the mains instantly after.

    The amp is an Orange AD30r, it uses 3 ECC83s (12ax7s) (preamp, phase inverter, reverb) and 4 EL84s and a GZ34.

    Here's a schematic just in case,

    http://www.prowessamplifiers.com/schematics/images/OrangeAD30_1.pdf

    I'm really hoping that this just needs a tube swap and not a trip to a tech because this thing weighs a lot.
     

  2. Wyatt

    Wyatt Tele-Holic

    804
    Nov 3, 2004
    HT=high tension (the plate voltage feed), not heater

    A blown power tube is the most likely culprit. Pull all the tubes, replace the fuses, and turn on and see if the fuses blow. If a fuse blows with no tubes in, it's serious and time for a tech.

    If the fuses remains intact, then you turn off, insert he GZ34 and test again. Finally, turn off and insert the power tubes and test again.

    But note, if fuses keep blowing it's because there is something wrong and if it's a serious short, you are risking further damage.
     
    SnidelyWhiplash, cap47 and Wally like this.

  3. Asmith

    Asmith Friend of Leo's Ad Free Member

    Age:
    21
    Nov 27, 2014
    Morley, England
    You learn something new everyday thanks for correcting me, I'll give that a go and if it's tech time it's tech time. :rolleyes:
     

  4. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    You should be in good shape - that's almost always a bad rectifier or power tube.

    If it is a power tube there's no way for you to know which one. It's best to replace them as a matched set anyway.
     

  5. Asmith

    Asmith Friend of Leo's Ad Free Member

    Age:
    21
    Nov 27, 2014
    Morley, England
    Thanks, after this set back I'm thinking I need an amp with fewer valves, it's not cheap when it needs doing but that's the nature of the beast. I still a love this amp and having it out of action has made me realise how much I'd miss it.
     

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