"b" wrote in message
ups.com...

Arfa Daily ha escrito:

Hi

Has anyone got schematics for an Aiwa MX-Z9500MK that they could either
have
a look at for me, or scan ? Need to know how the VFD filament supply is
derived - and before everyone rushes to say " I think it's via a cap ",
in
this Aiwa model, it's not.

Thanks


Nothing listed for this model. I'm not desperate, as the system is not worth
that much, but as it was apart on the bench, and I had sorted the
missing -24v problem, it was a bit annoying that I still had trouble with
the filament supply. This appears to be switched with a couple of
transistors near to the -24v reg. They actually derive the -24 on this
model, direct from a rectifier, rather than by the more traditional Aiwa
voltage multiplier. I don't really know why they bother switching the
filament supply to unused displays when the unit is off. Possibly to
preserve their life, I guess, but I have seen plenty of units where the
filament supply is always on. Anyway, having found these transistors, I went
looking for a control signal, but I couldn't find anything in the area that
moved when you switched from standby to on. There is a little surface mount
digital transistor that looks as though it ought to control this lot, and
what should be the base leg, has print disappearing off towards the front
panel, but as I say, no movement of voltages around it. Just for sport, I
tried shorting across the switch transistor, and this immediately restored
filament volts, and display on the amp, but still no filament volts up the
bus to the graphic, so that remained dead. That was the point that I called
it a day, and posted the request just to see if anyone had a manual.

No matter though, I have wrapped it back up now, and told the shop that
booked it in that the only way that it is going ahead, is if a service
manual could be found. They have indicated that they don't think that their
customer will want to be bothered, so it will finish up now as just another
of those jobs that end up only just about covering their time ... Thanks for
the suggestion anyway.

Arfa
Arfa

have you tried eserviceinfo?