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From: Arfa Daily on 15 Jul 2010 12:14
Anyone by any chance got any schematics for this ? I've tried all the usual
freebie sources, but without luck. Couple of places are offering them for
sale, but owners don't want to spend a lot on the repair, so I'm reluctant
to go down that route.

Problem is fairly straightforward, and is around the final mixdown / master
area, so that's the bit that I need a schematic for. Buried down between the
master sliders, are two s.m. dual opamps. Outputs are equal at the two
halves of one of them, but one side is low at the other. Around these two
opamps, the area is littered with gnat's-bollock-sized s.m. resistors, and
I'm pretty sure that one of these is o/c or high (it's not the opamp
itself - I changed it just in case) but because of the awkwardness of the
location and the size of the R's, it's a might difficult to see what's
connected to where, or to 'buzz' them to the IC pins. It's one of those jobs
that 'feels' as if it would resolve in a few minutes, with the benefit of a
schematic of the area :-)

Ta all !

Arfa

From: N_Cook on 16 Jul 2010 07:44
Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
news:btG%n.15942$mv6.13554(a)newsfe25.ams2...
> Anyone by any chance got any schematics for this ? I've tried all the
usual
> freebie sources, but without luck. Couple of places are offering them for
> sale, but owners don't want to spend a lot on the repair, so I'm reluctant
> to go down that route.
>
> Problem is fairly straightforward, and is around the final mixdown /
master
> area, so that's the bit that I need a schematic for. Buried down between
the
> master sliders, are two s.m. dual opamps. Outputs are equal at the two
> halves of one of them, but one side is low at the other. Around these two
> opamps, the area is littered with gnat's-bollock-sized s.m. resistors, and
> I'm pretty sure that one of these is o/c or high (it's not the opamp
> itself - I changed it just in case) but because of the awkwardness of the
> location and the size of the R's, it's a might difficult to see what's
> connected to where, or to 'buzz' them to the IC pins. It's one of those
jobs
> that 'feels' as if it would resolve in a few minutes, with the benefit of
a
> schematic of the area :-)
>
> Ta all !
>
> Arfa
>

How are the back retainers to the nearby sliders ? Could someone have lent
on the top and pushed in the sliders and produced a crack in that area.
finger prodding results?


From: Arfa Daily on 16 Jul 2010 20:54


"N_Cook" <diverse(a)tcp.co.uk> wrote in message
news:i1pgm8$ejm$1(a)news.eternal-september.org...
> Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
> news:btG%n.15942$mv6.13554(a)newsfe25.ams2...
>> Anyone by any chance got any schematics for this ? I've tried all the
> usual
>> freebie sources, but without luck. Couple of places are offering them for
>> sale, but owners don't want to spend a lot on the repair, so I'm
>> reluctant
>> to go down that route.
>>
>> Problem is fairly straightforward, and is around the final mixdown /
> master
>> area, so that's the bit that I need a schematic for. Buried down between
> the
>> master sliders, are two s.m. dual opamps. Outputs are equal at the two
>> halves of one of them, but one side is low at the other. Around these
>> two
>> opamps, the area is littered with gnat's-bollock-sized s.m. resistors,
>> and
>> I'm pretty sure that one of these is o/c or high (it's not the opamp
>> itself - I changed it just in case) but because of the awkwardness of the
>> location and the size of the R's, it's a might difficult to see what's
>> connected to where, or to 'buzz' them to the IC pins. It's one of those
> jobs
>> that 'feels' as if it would resolve in a few minutes, with the benefit of
> a
>> schematic of the area :-)
>>
>> Ta all !
>>
>> Arfa
>>
>
> How are the back retainers to the nearby sliders ? Could someone have lent
> on the top and pushed in the sliders and produced a crack in that area.
> finger prodding results?
>
>

No pcb / print damage that I can see. Operation of mixer in general, quite
stable. Adjacent master faders look original and free of any stress or
damage. Voltages between halves of dual opamp pretty similar. Gain of the
'low' side can be brought up to match the other side, with a wet finger
around the pins ...

Arfa

From: N_Cook on 17 Jul 2010 02:58
Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
news:cb70o.86694$hS4.86180(a)newsfe26.ams2...
>
>
> "N_Cook" <diverse(a)tcp.co.uk> wrote in message
> news:i1pgm8$ejm$1(a)news.eternal-september.org...
> > Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
> > news:btG%n.15942$mv6.13554(a)newsfe25.ams2...
> >> Anyone by any chance got any schematics for this ? I've tried all the
> > usual
> >> freebie sources, but without luck. Couple of places are offering them
for
> >> sale, but owners don't want to spend a lot on the repair, so I'm
> >> reluctant
> >> to go down that route.
> >>
> >> Problem is fairly straightforward, and is around the final mixdown /
> > master
> >> area, so that's the bit that I need a schematic for. Buried down
between
> > the
> >> master sliders, are two s.m. dual opamps. Outputs are equal at the two
> >> halves of one of them, but one side is low at the other. Around these
> >> two
> >> opamps, the area is littered with gnat's-bollock-sized s.m. resistors,
> >> and
> >> I'm pretty sure that one of these is o/c or high (it's not the opamp
> >> itself - I changed it just in case) but because of the awkwardness of
the
> >> location and the size of the R's, it's a might difficult to see what's
> >> connected to where, or to 'buzz' them to the IC pins. It's one of those
> > jobs
> >> that 'feels' as if it would resolve in a few minutes, with the benefit
of
> > a
> >> schematic of the area :-)
> >>
> >> Ta all !
> >>
> >> Arfa
> >>
> >
> > How are the back retainers to the nearby sliders ? Could someone have
lent
> > on the top and pushed in the sliders and produced a crack in that area.
> > finger prodding results?
> >
> >
>
> No pcb / print damage that I can see. Operation of mixer in general, quite
> stable. Adjacent master faders look original and free of any stress or
> damage. Voltages between halves of dual opamp pretty similar. Gain of the
> 'low' side can be brought up to match the other side, with a wet finger
> around the pins ...
>
> Arfa
>


I have a nice old optics part (the rack and pinnion section got worn out) of
a Watson Barnet x50 stereo surface viewing microscope for this sort of work,
reading SM labelling. The lenses are about 30mm from the object so clears
the slider housings and some high power white LEDs for slant or normal
illumination to get in under.


From: Arfa Daily on 17 Jul 2010 04:56


"N_Cook" <diverse(a)tcp.co.uk> wrote in message
news:i1rkb8$lvv$1(a)news.eternal-september.org...
> Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
> news:cb70o.86694$hS4.86180(a)newsfe26.ams2...
>>
>>
>> "N_Cook" <diverse(a)tcp.co.uk> wrote in message
>> news:i1pgm8$ejm$1(a)news.eternal-september.org...
>> > Arfa Daily <arfa.daily(a)ntlworld.com> wrote in message
>> > news:btG%n.15942$mv6.13554(a)newsfe25.ams2...
>> >> Anyone by any chance got any schematics for this ? I've tried all the
>> > usual
>> >> freebie sources, but without luck. Couple of places are offering them
> for
>> >> sale, but owners don't want to spend a lot on the repair, so I'm
>> >> reluctant
>> >> to go down that route.
>> >>
>> >> Problem is fairly straightforward, and is around the final mixdown /
>> > master
>> >> area, so that's the bit that I need a schematic for. Buried down
> between
>> > the
>> >> master sliders, are two s.m. dual opamps. Outputs are equal at the two
>> >> halves of one of them, but one side is low at the other. Around these
>> >> two
>> >> opamps, the area is littered with gnat's-bollock-sized s.m. resistors,
>> >> and
>> >> I'm pretty sure that one of these is o/c or high (it's not the opamp
>> >> itself - I changed it just in case) but because of the awkwardness of
> the
>> >> location and the size of the R's, it's a might difficult to see what's
>> >> connected to where, or to 'buzz' them to the IC pins. It's one of
>> >> those
>> > jobs
>> >> that 'feels' as if it would resolve in a few minutes, with the benefit
> of
>> > a
>> >> schematic of the area :-)
>> >>
>> >> Ta all !
>> >>
>> >> Arfa
>> >>
>> >
>> > How are the back retainers to the nearby sliders ? Could someone have
> lent
>> > on the top and pushed in the sliders and produced a crack in that area.
>> > finger prodding results?
>> >
>> >
>>
>> No pcb / print damage that I can see. Operation of mixer in general,
>> quite
>> stable. Adjacent master faders look original and free of any stress or
>> damage. Voltages between halves of dual opamp pretty similar. Gain of the
>> 'low' side can be brought up to match the other side, with a wet finger
>> around the pins ...
>>
>> Arfa
>>
>
>
> I have a nice old optics part (the rack and pinnion section got worn out)
> of
> a Watson Barnet x50 stereo surface viewing microscope for this sort of
> work,
> reading SM labelling. The lenses are about 30mm from the object so clears
> the slider housings and some high power white LEDs for slant or normal
> illumination to get in under.
>
>

I have a high power stereo microscope, complete with its base and mechanics,
and area illumination, which I use for similar things to yourself. I also
have a high intensity white LED set in the end of an old biro pen tube. Very
handy for close-in high intensity illumination, or getting some light into
awkward places. I might dig it out and have a look, but I'm pretty sure that
this is a genuine electronic fault, rather than a pcb damage thing. Either
way, it would be a lot easier to track down with the benefit of a schematic
for the area.

Arfa

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