UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Marshall JTM45 Guitar Amplifier- Mains (Primary)Fuse Blows

'LIVEWIRE?' · 11th Aug 2018, 9:11 am

Could this be a Mains Transformer fault? (Hope Not!) The Primary DC resistance measures about 8 ohms on my DMM. Other than that I haven't yet carried out any tests, but I'm told that the (correct) 2A(T) fuse in the Mains TX primary circuit has blown more than once. The HT fuse (500mA(T) remains intact. There is no suppressor cap. across the mains i/p, which was my first thought. As noted, I've yet to try measuring the primary current, or taking any other measurements, besides noting that the HT Secondary DC resistance is about 40 ohms.

11th Aug 2018, 9:11 am	#1
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Marshall JTM45 Guitar Amplifier- Mains (Primary)Fuse Blows Could this be a Mains Transformer fault? (Hope Not!) The Primary DC resistance measures about 8 ohms on my DMM. Other than that I haven't yet carried out any tests, but I'm told that the (correct) 2A(T) fuse in the Mains TX primary circuit has blown more than once. The HT fuse (500mA(T) remains intact. There is no suppressor cap. across the mains i/p, which was my first thought. As noted, I've yet to try measuring the primary current, or taking any other measurements, besides noting that the HT Secondary DC resistance is about 40 ohms.