It doesn't make sense to me as a technican.
Why?
Because some tube amps/equipment have solid state rectifiers that if powered up without any loading can inject high peak DC voltages into the main filter capacitors.
And if those capacitors are stressed by the over-voltage now on them, can heat up, leak, and worst case, explode.
It's bad enough when working on tube equipment that strict safety proedures are followed, and someone not familier with them can be prone to being hurt.
Proper troubleshooting procedures require proper tools/testing equipment, and enough experience to carry out procedures in a safe way.
Looking at Rayma's schematic, the Pre-amp heaters use the OP cathode current, which is unusual and unexpected, and creates dependencies.
Exactly, there are so many exceptions to the rule. It's a real problem for the novice.
Most circuits were not designed to be easily repaired, or to facilitate troubleshooting.
Most circuits were not designed to be easily repaired, or to facilitate troubleshooting.
My DIY tube monoblock blew its fuse once with a loud bang. This was during operation, not at turning on. It took the mains interrupter at the house distribution table too. It had been working well for a couple of weeks before.
I carefully checked everything: cabling, tubes, filter capacitors, but did not find anything. Then I turned it on using a 100W lamp in series with the mains, no issue found. It has been working fine since then.
I carefully checked everything: cabling, tubes, filter capacitors, but did not find anything. Then I turned it on using a 100W lamp in series with the mains, no issue found. It has been working fine since then.