Hello everyone, I have a Micromega MyGroov phono preamplifier. It's based on AD SSM2019, OPA1642, and LM4562. It's both an MM and MC preamp, but the problem is only with MM operation. MC works fine. It's not the cartridge, nor the turntable as everything works fine with other phono preamps.
The problem is incredibly strange. It's completely random. Sometimes it can last for days, other times for minutes, hours.
Basically the sonic quality takes a hit. One moment everything sounds amazing, the next it sounds as if listening to a poor indistinct MP3. This doesn't happen gradually, but immediately.
I can even catch the change mid song sometimes. The highs become flat/dull. Several records later, its back to normal. And this random cycle continues on.
Any ideas on what it may be? Failing OP amp? Oscillations?
The problem is incredibly strange. It's completely random. Sometimes it can last for days, other times for minutes, hours.
Basically the sonic quality takes a hit. One moment everything sounds amazing, the next it sounds as if listening to a poor indistinct MP3. This doesn't happen gradually, but immediately.
I can even catch the change mid song sometimes. The highs become flat/dull. Several records later, its back to normal. And this random cycle continues on.
Any ideas on what it may be? Failing OP amp? Oscillations?
The unit is less than a year old, so all of the connectors look brand new. There are many Omron relays inside for turn on, switching, and mute functions, I suppose one of those could be going bad?
One year old...ask for warranty coverage.
One more reason to make the rotten unknown stuff fail for good.
Carefull visual inspection can help.
I found a bad solder joint ( dry, dull looking ) that was doing a random unfrequent behavior.
In the early ages of not so reliable hardware the tricks to debug hardware were, heat cold, over voltage under voltage, over clocking underclocking.
One more reason to make the rotten unknown stuff fail for good.
Carefull visual inspection can help.
I found a bad solder joint ( dry, dull looking ) that was doing a random unfrequent behavior.
In the early ages of not so reliable hardware the tricks to debug hardware were, heat cold, over voltage under voltage, over clocking underclocking.
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Moved to Analogue Source (well it is a phono stage)
Hook up a 1kHz square wave generator and an inverse RIAA network to the inputs,
and a scope to the outputs. Run it until you see a problem, and then take a photo
of the screen and send it to the mfr, since it's in warranty. They'll know what to do,
with the photo showing the behavior. If possible though, exchange it for a new one
at the dealer where you bought it.
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I have another MyGroov phono and it works great with the same MM cartridge. But I still need to fix the faulty one.
I bought it from Music Direct, they no longer carry Micromega. I rather fix this myself.
Ok, then post a photo of the outputs when it has the problem. Do you have the schematic?
If these are signal relays with gold-clad contacts in an enclosure that blocks all dust, then it seems unlikely - but you never know, of course.
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