Hello,I have an old amplifier from the Soviet era, which I am trying to get into a working condition, just like the speakers, for fun. It has the habit of blowing the fuse (1.6A small cylindrical fuse) either immediately when turning it on (most of the time) or after a random amount of time. Volume doesn't seem to be a factor.I tried using fast/middle/slow reacting (is that the term?) fuses and all of them seem to be acting nearly the same. I disassembled it and the cable that goes "through the fuse" goes to the transformer. Could it be faulty and not producing stable output? How could I test that? If it's the transformer, can I build one myself (or repair this one)? If yes, how do I find out it's specs and how much would it approximately cost? I have the instruction manual with a complete electrical scheme for the amplifier, which I could scan and upload, if that would help in any way.I'm basically a newbie who likes to tinker with stuff, so I am completely clueless about the difficulty of this. Soldering is not a problem.
Yes, I am aware of the dangerous voltages, thanks for reminding. About the only difference I can see in the line is that in Germany, the line is rated 230V and back in Latvia it was 220V. Could this be the reason?
Unless the line voltage was more than 10% higher I doubt it would be an issue.
I scanned that part of the electrical scheme (full scheme will follow if needed) and uploaded it here
But tube amps? Likely need an adjustment or new tubes (and likely an adjustment due to new tubes).
This is the mains input fuse. When it blows the amp is drawing too much power, doing so under idle conditions makes me think you should test and replace components before replacing the fuse too many more times. I don't see it as safe to proceed as it is.
OK, let's look at the various suggestions.Capacitors are certainly a limited life item, and the large filter caps could cause problems like blown fuses. Replacing electrolytic caps in old equipment is usually a good idea.
Well, Porcus said something about the tubes so I got confused
And what do you mean by "none of them is conducting" – you haven't ... uhm ... connected them serially to a lightbulb and tested with ... a ... battery?
Nobody puts extra unneeded parts in amps, replace them with same value known good devices.
Caps C1, C2, C3 must be special mains-rated types (X and Y class (sorry, only the German Wikipedia entry covers this in detail)). Specifically, it would be some X class here. Reichelt carries WIMA MP3-X2 series 22n and 47n types, for example. Possibly the original types weren't such caps and could no longer sustain the voltage spikes that occurred.
I'm kinda surprised the designers didn't put spark extinguisher caps or R-C combos across the power switch (those would have to be Y class devices, I think). That tends to result in burned contacts in the long run.