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Old 14th Aug 2018, 9:44 am   #36
Omegaman
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Join Date: Dec 2009
Location: Leeds, West Yorkshire, UK.
Posts: 250
Default Re: Marshall JTM45 Guitar Amplifier- Mains (Primary)Fuse Blows

Quote:
Originally Posted by 'LIVEWIRE?' View Post
Thanks for the info, SB. In the meantime I have found, by following the good advice given by various forum members, that the fuse blows due to the GZ34 flashing over after 30 seconds to 1 minute after switching on the amp, with the HT fuse removed and the 'standby switch 'off'. I now have to get a new GZ34. I note that Howard (omegaman) recommends Sovtek rectifiers, whilst Joebog1 says he only uses genuine Mullard, RCA, or GE ones. Which to get? I've left a message that a new GZ34 can be had for around £20, but have also seen them at prices up to and even over £100. A firm in Kidlington, not far from where I live is selling Golden Dragon GZ34's for £18 + P&P so, maybe I'll get one of those. Needs thinking about!!
The flashing over a short while after switch on seems to be common.
In my experience, the Sovtek GZ34 is the best value for money and has a reasonable longevity. True, a genuine Mullard or GE type will last and work the best, but your average guitar player won't pay the eye watering prices usually charged for one! The JJ ones are poor and I've had several that flash over straight out of the box! Swapped for a Sovtek and no problem. The Chinese ones are actually very good. These can be often branded TAD (Tube Amp Doctor) but are actually Shuguan valves.
Best price for Sovtek ones I've found is Hotrox in Nottingham (No connection).

I'd stick with a T2A mains fuse.
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