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

Argus25 · 14th Aug 2018, 7:26 am

Partly related to this topic, when I built my Argus TV's I initially fitted it with a Russian made 5U4. When I initially powered it, the tube flashed over and I thought I might have had a circuit or component fault. But after comparing it to an RCA 5U4 and GEC U52, I found it was the Russian 5u4 that was prone to it. So I tried another, the same. The internal construction of the rectifier looked good otherwise with springs to support the filament.
I have always found GZ34's to be a very good rectifier and they drop less forward voltage than a 5U4 and run cooler for the same current.

14th Aug 2018, 7:26 am	#34
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Marshall JTM45 Guitar Amplifier- Mains (Primary)Fuse Blows Partly related to this topic, when I built my Argus TV's I initially fitted it with a Russian made 5U4. When I initially powered it, the tube flashed over and I thought I might have had a circuit or component fault. But after comparing it to an RCA 5U4 and GEC U52, I found it was the Russian 5u4 that was prone to it. So I tried another, the same. The internal construction of the rectifier looked good otherwise with springs to support the filament. I have always found GZ34's to be a very good rectifier and they drop less forward voltage than a 5U4 and run cooler for the same current.