It could be down to a variety of things.
My first thing to try would be to check that VR1 is giving 0V at CP6.
Is the problem the same regardless of which transpose key is on?
If not and it's more pronounced on one, I'd start with the associated
circuitry for that octave i.e. FET1& TR1, or FET2 & TR2 etc.
Check that the voltage at the Transpose keys is correct (+15V)
It could be a leaky FET causing the issue (FET1-4), or possibly one of
the transistors (TR1-5)
It sounds like the FET/Transistor hasn't gone completely, but it on it's
way, so testing it with a component tester may not find it.
It might even be IC7 or TR5 (More likely if the problem is regardless of
octave)
I think you're just going to have to go thorough it systematically until
you get it.
I wouldn't read too much into the pitch rising when you probe CP6. It's
just an indication that there's something not right wit the circuit.
Sorry if all that doesn't sound that helpful, but there are only about
12 components involved, so it's got to be one of them.
B
On 22/05/2013 11:24, Quazimodo wrote:
>
> No there is a fault.
>
> The voice will not tune into range.. it is very low compared to the
> others as is the voltage on CP6. The effect I get is when I check the
> voltage on CP6 whilst listening to the voice - the pitch rising - I
> only mentioned as I thought it might be a clue...!
>
> --- In yamahacs80@yahoogroups.com
> <mailto:yamahacs80%40yahoogroups.com>, "Laurie Curry" <laurie@...> wrote:
> >
> > I know if you dont use insulated screwdrivers when tuning, the pitch
> will sharpen slightly...and then flatten as you pull away... i assume
> thats the effect you are indicating...
> >
> > -----Original Message-----
> > From: Quazimodo <noddyspuncture@...>
> > To: yamahacs80@yahoogroups.com <mailto:yamahacs80%40yahoogroups.com>
> > Date: 05/21/13 19:17
> > Subject: [POSSIBLE SPAM] [yamahacs80] Out of tune voice... still
> out, so posting again...
> >
> > Â Â Â
> > Hi guys,
> >
> > I see there's some activity lately here so I thought I'd try again.
> I posted this before but there were no replies...
> >
> > I have an out-of-tune 'M' card. CP6 always reads a lot lower on this
> faulty 'M' card than on the other good voices.
> >
> > The voice is out of tune, and low in pitch. When I play that voice
> and then measure CP6, the pitch rises due to my meter prong's contact.
> >
> > Has anyone had this symptom before?
> >
> > Cheers,
> > TOM
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
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