Hi all. Long time no post!
My friend gave me his Metro JTM45 amp that I built for him years ago. Up until now it had been working beautifully but according to him it just wouldn't turn on one day.
I have had a bit of an inspection and basically both fuses were blown. I replaced the fuses and tested the voltages and right when I flipped the standby off both fuses blew again. I replaced the rectifier tube and this half fixed the problem, the mains fuse stays intact but the HT fuse blows when turning off standby. This is with no power tubes installed, just preamp tubes and rectifier tube. So now I am a little stumped as to what to check next? My guess is one or more of the power tubes failed and took some things with it. Everything looks to be intact, with nothing burned out that I can see.
Any suggestions?
HT fuse blowing with no tubes installed
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marT
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Elad E
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Re: HT fuse blowing with no tubes installed
until the experts chime in,what kind of fuse you have there?
correct value is 500mA Slo Blo - I put fast blo fuses and upon hitting the Stby switch often blew the fuse.
the advice I was given here is to leave Stby on as the spike from the stby switch kills rectifier tubes and the GZ34 having a slow warm up makes having a standby switch redundant anyway. since then the standby switch has been left On and no further fuses were lost.
correct value is 500mA Slo Blo - I put fast blo fuses and upon hitting the Stby switch often blew the fuse.
the advice I was given here is to leave Stby on as the spike from the stby switch kills rectifier tubes and the GZ34 having a slow warm up makes having a standby switch redundant anyway. since then the standby switch has been left On and no further fuses were lost.
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marT
- Senior Member
- Posts: 712
- Joined: Mon Dec 04, 2006 7:21 am
- Location: Adelaide, Australia
Re: HT fuse blowing with no tubes installed
I have been using 500ma fast blows. Thats what was in there before and had no issues until now. I'll test your theory and see how I go though.
EDIT: yep, you are right, that didn't pop the fuse. Now I need to find my speaker cable for my dummy load and get it all biased up. Cheers! Still a bit strange that using the standby never used to be a problem though, maybe these fuses are a bit more sensitive than what I was using before.
EDIT: yep, you are right, that didn't pop the fuse. Now I need to find my speaker cable for my dummy load and get it all biased up. Cheers! Still a bit strange that using the standby never used to be a problem though, maybe these fuses are a bit more sensitive than what I was using before.