Yamaha CS80

Hello all,

I am restoring a PSU in a CS60 and after recapping i have no +15v but
the +8.5 is fine.

I'm thinking it could be the power transistor attached to the 15v rail
however the reading of ~1.5v at the business end suggests otherwise.

Before i go swapping out parts, can anyone suggest a fix? I've checked
all the capacitors for polarity and continuity to the relevant traces.

Andrew


Andrew Kirkby
(e) kirkbyte@...
(m) 0416 000 070

If it was working before you changed the caps then I would suspect it is something you have done.

Treble check all your work..!!!

Cheers,
TOM

--- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@...> wrote:
>
> Hello all,
>
> I am restoring a PSU in a CS60 and after recapping i have no +15v but
> the +8.5 is fine.
>
> I'm thinking it could be the power transistor attached to the 15v rail
> however the reading of ~1.5v at the business end suggests otherwise.
>
> Before i go swapping out parts, can anyone suggest a fix? I've checked
> all the capacitors for polarity and continuity to the relevant traces.
>
> Andrew
>
>
> Andrew Kirkby
> (e) kirkbyte@...
> (m) 0416 000 070
>

Tom,

It looks like a trace lifted when i put the board back. Fixed that and
now it works perfectly :)


I now have another problem on the top octave now - i can't get any
sound unless a key from an octave below it, then i get crazy sounds
without correct pitch. Looks like a morning on the scope is needed :)

AK

On 14/07/2011, at 10:38 PM, Quazimodo wrote:

> If it was working before you changed the caps then I would suspect
> it is something you have done.
>
> Treble check all your work..!!!
>
> Cheers,
> TOM
>
> --- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@...> wrote:
> >
> > Hello all,
> >
> > I am restoring a PSU in a CS60 and after recapping i have no +15v
> but
> > the +8.5 is fine.
> >
> > I'm thinking it could be the power transistor attached to the 15v
> rail
> > however the reading of ~1.5v at the business end suggests otherwise.
> >
> > Before i go swapping out parts, can anyone suggest a fix? I've
> checked
> > all the capacitors for polarity and continuity to the relevant
> traces.
> >
> > Andrew
> >
> >
> > Andrew Kirkby
> > (e) kirkbyte@...
> > (m) 0416 000 070
> >
>
>
>

Andrew Kirkby
(e) kirkbyte@...
(m) 0416 000 070






[Non-text portions of this message have been removed]

That don't make sense... can you explain it better Andrew..!

"...unless a key from an octave below it" ...?

--- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@...> wrote:
>
> I now have another problem on the top octave now - i can't get any
> sound unless a key from an octave below it, then i get crazy sounds
> without correct pitch. Looks like a morning on the scope is needed :)
>
> AK
>

ok,

So, all keys up until the top D key work fine. If i press a single key
above top D i get no sound whatsoever BUT if i hold a key below the
top D key and one above at the same time it will produce the note
below top D correctly and the note above with lots of distortion and
the wrong pitch.

If i press 8 keys located below the top D key, all voices work fine so
i know it's not an issue with a M board.

I have checked the ICs on the lower boards and have found some strange
behaviour on IC12 of the KAS board (4016). If i measure the voltage
between ground and pins 8 or 9 while pressing a low key on the
keyboard, i get a small voltage (1-3 volts) on the meter. If i press a
key above that D key i get a negative voltage around -4.5 volts. No
lower key press gives a negative voltage.


Andrew

On 16/07/2011, at 5:19 AM, Quazimodo wrote:

> That don't make sense... can you explain it better Andrew..!
>
> "...unless a key from an octave below it" ...?
>
> --- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@...> wrote:
> >
> > I now have another problem on the top octave now - i can't get any
> > sound unless a key from an octave below it, then i get crazy sounds
> > without correct pitch. Looks like a morning on the scope is
> needed :)
> >
> > AK
> >
>
>
>

Andrew Kirkby
(e) kirkbyte@...
(m) 0416 000 070






[Non-text portions of this message have been removed]

Hi Andrew,

The only time I ever had anything similar to this was a fault affecting mainly the after touch - but also, I seem to remember there were actual *note* issues. The fault in my case was around one of the TSB boards. I turned out to be one broken wire! What I would do in the first instance is play those high notes that are the problem - whilst gently moving the wires going to the boards - TSB, TKC and KAS.

Have you been handling any of these boards repeatedly? Turning them to and fro during re-capping for example can I would guess, cause problems.

Cheers
TOM

--- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@...> wrote:
>
> ok,
>
> So, all keys up until the top D key work fine. If i press a single key
> above top D i get no sound whatsoever BUT if i hold a key below the
> top D key and one above at the same time it will produce the note
> below top D correctly and the note above with lots of distortion and
> the wrong pitch.
>
> If i press 8 keys located below the top D key, all voices work fine so
> i know it's not an issue with a M board.
>
> I have checked the ICs on the lower boards and have found some strange
> behaviour on IC12 of the KAS board (4016). If i measure the voltage
> between ground and pins 8 or 9 while pressing a low key on the
> keyboard, i get a small voltage (1-3 volts) on the meter. If i press a
> key above that D key i get a negative voltage around -4.5 volts. No
> lower key press gives a negative voltage.
>
>
> Andrew
>
>
> On 16/07/2011, at 5:19 AM, Quazimodo wrote:
>
> > That don't make sense... can you explain it better Andrew..!
> >
> > "...unless a key from an octave below it" ...?
> >
> > --- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@> wrote:
> > >
> > > I now have another problem on the top octave now - i can't get any
> > > sound unless a key from an octave below it, then i get crazy sounds
> > > without correct pitch. Looks like a morning on the scope is
> > needed :)
> > >
> > > AK
> > >
> >
> >
> >
>
> Andrew Kirkby
> (e) kirkbyte@...
> (m) 0416 000 070
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

Tom,

Given that this is a CS 60 there are no TSB or TKC boards.

I will swap out that IC12 on the KAS and see if the issue remains.
INverting voltage on that type of CMOS is indicative of failure (maybe
due to static or something else while changing those caps) - this
1970s CMOS is pretty terrible.

I have already tested all of the wiring and it all seems OK.

Thanks,


Andrew

On 16/07/2011, at 9:28 AM, Quazimodo wrote:

> Hi Andrew,
>
> The only time I ever had anything similar to this was a fault
> affecting mainly the after touch - but also, I seem to remember
> there were actual *note* issues. The fault in my case was around one
> of the TSB boards. I turned out to be one broken wire! What I would
> do in the first instance is play those high notes that are the
> problem - whilst gently moving the wires going to the boards - TSB,
> TKC and KAS.
>
> Have you been handling any of these boards repeatedly? Turning them
> to and fro during re-capping for example can I would guess, cause
> problems.
>
> Cheers
> TOM
>
> --- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@...> wrote:
> >
> > ok,
> >
> > So, all keys up until the top D key work fine. If i press a single
> key
> > above top D i get no sound whatsoever BUT if i hold a key below the
> > top D key and one above at the same time it will produce the note
> > below top D correctly and the note above with lots of distortion and
> > the wrong pitch.
> >
> > If i press 8 keys located below the top D key, all voices work
> fine so
> > i know it's not an issue with a M board.
> >
> > I have checked the ICs on the lower boards and have found some
> strange
> > behaviour on IC12 of the KAS board (4016). If i measure the voltage
> > between ground and pins 8 or 9 while pressing a low key on the
> > keyboard, i get a small voltage (1-3 volts) on the meter. If i
> press a
> > key above that D key i get a negative voltage around -4.5 volts. No
> > lower key press gives a negative voltage.
> >
> >
> > Andrew
> >
> >
> > On 16/07/2011, at 5:19 AM, Quazimodo wrote:
> >
> > > That don't make sense... can you explain it better Andrew..!
> > >
> > > "...unless a key from an octave below it" ...?
> > >
> > > --- In yamahacs80@yahoogroups.com, Andrew Kirkby <kirkbyte@>
> wrote:
> > > >
> > > > I now have another problem on the top octave now - i can't get
> any
> > > > sound unless a key from an octave below it, then i get crazy
> sounds
> > > > without correct pitch. Looks like a morning on the scope is
> > > needed :)
> > > >
> > > > AK
> > > >
> > >
> > >
> > >
> >
> > Andrew Kirkby
> > (e) kirkbyte@...
> > (m) 0416 000 070
> >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>

Andrew Kirkby
(e) kirkbyte@...
(m) 0416 000 070






[Non-text portions of this message have been removed]