Arfa Daily wrote in message
...

"n cook" wrote in message
...
Retro look of the 1960s Vox AC30 amp made probably 2004 with lots of SM
digital chippery for effects undreamt of in the 60s.
One 12AX7 , but is it for show only ?
Heaters have an AC supply but the anodes don't seem have any HV
components
attached to them. The speaker o/p is a non-retro National Semi LM3886T.
I've not powered up yet as only poking around cold at the moment as I've
never seen the like before, all seems DVM ok for power supplies etc.
Apparently went pop between songs and then no more.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



I had one of these in for repair a while back. As far as I recall, the
triode stage is genuine, but not run from a particularly high HT voltage.
You can get away with some quite low anode voltages on these twin triodes.
Elektor mag have published a few circuits in recent years, where they have
run these at low HT. The digital simulations of various retro amp types,
was
actually remarkably good.

Arfa



Damn hybrid O/P devices , -V rail to o/p short on the LM3886T.
Not being abused and no audio troughput at all when it failed.
Is there a learned file on WWW on why these sort of devices fail ,
a loudspeaker wire short or heavy throughput you could understand.

So ten squid to replace rather than just a 3055 or 3773


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/