View Single Post
Old 11th Aug 2018, 10:03 am   #2
sortedradio
Heptode
 
sortedradio's Avatar
 
Join Date: Jan 2008
Location: Sheffield, South Yorkshire, UK.
Posts: 653
Default Re: Marshall JTM45 Guitar Amplifier- Mains (Primary)Fuse Blows

I would try removing the ht fuse and see whether the primary fuse still blows. If not I would suspect the output valves and check their anode current and biasing. If it still blows remove the rectifier, when they start to fail they often cause the primary fuse to blow. If it still blows it is looking like the transformer, although it would be worth removing all the valves and testing just in case there is a heater fault. If you have a lamp limiter you could use it to save fuses.
__________________
Martin
BVWS member
GQRP Club
sortedradio is offline