04-02-2018, 10:16 AM
We don't know which model this actually is - there are many possibilities - and they don't appear to give specifications for the power output, but I could well believe that 50V is used. Assuming that is a single 50V rail, a decent single-ended amplifier powered from 50V could deliver around 35 watts into 8 ohms. Lower impedances or BTL operation could yield considerably more. These "beat boxes" are known for being loud and aggressive (and rather expensive!), so a big PSU is not a surprise. Of course, the +/-7V rails are for op-amps, etc.
It's a switched-mode supply, so yes, diode bridge and smoothing caps straight off the mains. No idea what topology it uses from this point, but the fact there is no voltage across the primary of the transformer means that the supply isn't oscillating for whatever reason. From the limited descriptions given, it's not possible to determine if there is a start-up fault or an overload on the secondary side. If the latter, that could be because of a fault in the PSU, or it could be because of a faulty amplifier loading it down - no information has been given to enable us to eliminate that as a cause as yet.
If the folks at UKVRRR were unable to help, I'm doubtful that I can add much to this. It seems to me that the PSU either needs to be sent away to someone who specialises in PSU repair work - which, as soon as you're past the "changing knackered caps" level becomes a highly specialised field of work - or the unit written off as BER. I'd take a look, but I'd charge a proper rate for my time, with no guarantee of a result (I don't do no-fix, no-fee work for anything modern and disposable).
It's a switched-mode supply, so yes, diode bridge and smoothing caps straight off the mains. No idea what topology it uses from this point, but the fact there is no voltage across the primary of the transformer means that the supply isn't oscillating for whatever reason. From the limited descriptions given, it's not possible to determine if there is a start-up fault or an overload on the secondary side. If the latter, that could be because of a fault in the PSU, or it could be because of a faulty amplifier loading it down - no information has been given to enable us to eliminate that as a cause as yet.
If the folks at UKVRRR were unable to help, I'm doubtful that I can add much to this. It seems to me that the PSU either needs to be sent away to someone who specialises in PSU repair work - which, as soon as you're past the "changing knackered caps" level becomes a highly specialised field of work - or the unit written off as BER. I'd take a look, but I'd charge a proper rate for my time, with no guarantee of a result (I don't do no-fix, no-fee work for anything modern and disposable).
