I had a transformer fail in a Crown D-70, accord to the schematic it had +/- 30 Vdc rails, but I remember measuring around +/- 33. My buddy found a solution with older 24 Vac transformers. I have them wired in series to get me the two lines of 24 Vac to give the +/- rails. I have them on my variac and unloaded with 117 Vac input they put out about 28 Vac each. Once loaded and rectified by the Crown rectifier I have about 36 Vdc. The line voltage around here is usually 120-122 Vac. Sometimes Ive seen higher. I’m worried that off of the variac that the rail voltages will be too high, a third higher than the manual spec. The main filters are rated for 40 Vdc.
Opinions?
Dan
Opinions?
Dan
Transformers drop a little voltage under load from ~10% for small ones to ~3-4% for large power amplifier ones, plus the designer would normally allow for mains voltage being 10-15% over nameplate rating. Crown gear is pretty bulletproof and they would have designed it to run pretty hard as a professional amplifier, so provided you don't have any power surges you're probably still within the design envelope for the product. Bear in mind it may run hot with higher bias currents and more voltage drop across power supply regulators with the higher rails. If you drive it hard it will be more likely to shut down with over-temperature than with the correct transformer. It would pay to check / readjust if necessary the bias back to spec current with the higher rails.
Depends on the current or Volt Amp rating of your transformers
Under load driving a speaker the rails will sag.
As mentioned small transformers will have higher voltage with no load.
Transformers rarely fail, so the real question is why the transformer failed.
And how was it determined the transformer failed.
You have to understand its basically a inside joke with many repair shops
that the symptom of a bad amp is always " a bad transformer"
when 90% of the time it has nothing to do with the transformer.
You can replace the transformer if it was damaged.
But its likely whatever killed the transformer is still un repaired.
Or is likely the transformer is fine.
Under load driving a speaker the rails will sag.
As mentioned small transformers will have higher voltage with no load.
Transformers rarely fail, so the real question is why the transformer failed.
And how was it determined the transformer failed.
You have to understand its basically a inside joke with many repair shops
that the symptom of a bad amp is always " a bad transformer"
when 90% of the time it has nothing to do with the transformer.
You can replace the transformer if it was damaged.
But its likely whatever killed the transformer is still un repaired.
Or is likely the transformer is fine.