So did i
Maybe it was a fluke, it has been running cooler with lowered voltage. I have changed all tubes except the EL 34, my repair guy told me not to change them, they were inside specks, maybe one went nuclear. I had already bought 4 new ones, they are going in now. No diagnosis yet. I have this whole ritual, i turn on the system and wait 5 minutes, then i cross myself, with fingers crossed 2 times and turn on the first power supply of the Io, wait 2 minutes, cross myself 3 times with fingers crossed and turn on the second power supply. I then wait until both lamps on the front of the power supplies are lit, and then start playing a cartridge with the preamp still muted, hoping he signal helps during warmup. Maybe i did not wait long enough between turning on the first and second power supply. Or maybe i am just superstitious, with a little OCD !
While this ritual may make you feel better. I assure you it has nothing to do with saving you from the unfortunate problems you are having. The Io is totally dual mono it it really doesn't care how long you wait between turning on or off channels of the separate chassis. Just don't snap things on-off-on quickly-- that's bad for other reasons.
I'd be looking at your B+ pass tubes - the el34's and their sockets - if the sockets are worn and you loose bias then you are in for nuclear fireworks down stream. It really doesn't matter that your Io is "newer" Chinese sockets are abysmal and they are prone to failure at any time. The metal quality loses its spring and the 'fun' begins. NOS American sockets practically last a lifetime. Unfortunately, this what the world has come to - The Japanese sockets available now are better.
Are your el34s current production?-- my experience is that current production tubes in this position are very prone to failure- not because of the Io- but because current production power tubes have a host of problems that are not culled out by many vendors today. Pay for screened tubes- even then, current production sucks in this critical position as they are time bomb waiting to go off.
Old stock is best here. While I have original Mullards, my stash is getting low after 20 years and I will have to move to my German RFT ( Siemens) which are the next best thing or Japanese Matsushita here soon. Still not inexpensive, but not Mullard prices and they wont go nuclear like the Russian , Slovakian or god forbid Chinese tubes. Sorry , I don't have any love for new power tubes of almost any type as the consequences of poor production can be catastrophic. I have old production EL34s and 6550s , 6V6s in various vintage amps and those tubes are at least 40 years old -- unthinkable with new production. We have little choice. Small signal tubes I can live with- they sound meh- but they generally won't destroy your equipment.
Also, we have heard that the Aesthetix products in this line up have had new transformers designed for them. We can guess why but we will not know the real answer.
Working with 220/240 should not have any affect on reliability versus 120 v types-- actually they might theoretically be less prone to problems because of less of a differential between primary and secondary. If I had to guess ----and I believe you have transformers that say "Mercury Magnetics". You 'may' have transformers whose insulation has intermittently broken down and point to a problem with the original quality of the specified part from Aesthetix or your el34 tubes or sockets are bad.
A good tech can leakage test the transformers with the right instrument. Ordinarily, this kind of failure is one of the last things you look for as a tech- but in this case we know that the transformers were re-designed and taken in house. So, there is a good reason to speculate here-where we ordinarily wouldn't do so.
FWIW the only real failure I had in my Io in 20+ years of ownership was the transformer and the requisite regulators associated with it- I changed both B+ and filament transformers on both units and upgraded the caps along with the replacement of regulator--- sound familiar?
Lastly I assume all the PS caps have been checked for ESR on the B+ and filaments and all the decoupling caps have been checked in the head unit for leakage. This is a pain in the _ss but it should be a maintenance item at this point- replace them all - they're not expensive but the labour component is gruesome.
My Io ran for 20+ years with Mercury Magnetics transformers before what sounds like a similar failure to yours --- the regulator and transformer for the B+ on that channel failed - what went first will always be a mystery.
Sorry for your experience Milan, I have been really pleased with my Io now Eclipse status with the new transformers- cost per day of ownership has been really low and a 20+ year run for a piece of stereo equipment that is actually supported by the mfr.-- I'm ok with based on its performance.
Good luck with your repair.
