[sdiy] Trouble shooting the PV-1 pitch to voltage converter
Joe Frey
joe.frey at radioles.com
Thu Jul 31 04:55:20 CEST 2014
Simon and list, Well fudge, I thought I had it finished. My PV-1 that
is. I can't calibrate this machine. Following Harry Bissels instructions
I am using one octave below middle c. That's C4 on a midi virtual
keyboard. I am supposed to be able to use a range trimmer and scale
trimmer to get 0V for the Pitch CV out. The closest I can get to 0V
pitch CV out is -0.28V. Here's a link to the schematic for anyone who
cares to have a look.
http://www.radioles.com/works/pv1_611-1.pdf
With the 2 trimmer pots set in about the middle of their range I get
-0.96V for my Pitch CV out. I checked the voltage on the trimmer pot
legs. On p02 I get 12.1V, 1,6V and -11.8V. On p01 I get -.07V on the
legs that are tied together and -0.5V on the other leg.
Both sides of R19 I get -0.9V. At u06 I get -.96V on pin1 and U06 pin7
is -1.37V. Thanks for the help. Joe.
Simon Brouwer wrote:
> Hi Joe,
>
>
> U02 pin 11 is normally low since both inputs are pulled to 12V by R06
> and R07. It becomes high if any of its inputs are low, which is at
> each falling edge on U02 pin 3 (through C03) and at each rising edge
> through U02 (2) and C04.
>
> The "low" pulses on U02 pin 11 will be short though so the average
> voltage on that pin (as measured with multimeter) will remain close to
> 12V.
>
> However, the fact that U04 pin 1 voltage reflects frequency indicates
> that U03 is being clocked all right.
>
> About the same (frequency dependent) voltage should be found at U05
> pin 8/11. It should come back at pin 9/10 (a bit higher, about twice
> that at pin 8 I expect). At U04 pin 7 it should be the same as at pin 5.
>
> Best regards
> Simon
>
>
>
> Joe Frey schreef op 29-7-2014 05:26:
>> Simon, And hopefully list.
>>> About the same voltage as on U04 pin 1 (i.e. dependent on the
>>> frequency) should be present on U04 pin 7, is it?
>> Similar voltage is not on u04 pin 1 and pin 7. I am sure that u04 pin 1
>> is changing with the frequency though.
>>
>> I am now starting again at the beginning. I am now at u02 which creates
>> the pulses that drive the circuit. I am able to follow the schematic OK
>> until I get to the input at u02 pin 11 and 12. This is 12.4 v which
>> seems ok though it seems very similar to the positive voltage at the
>> rails. I checked for a short but there wasn't one. I wonder, though u02
>> pin11 is supposed to output a positive pulse to drive the counter but
>> the voltage at that pin is only .001 volts?
>>
>>> With a positive voltage at U04 pin 7 it is strange that you get a
>>> positive voltage at the output, since the current going via R17 into
>>> pin 2 of U06 would cause U06 pin 1 to go negative (there should be no
>>> current going into Q04 (left) collector since with 0V at both the base
>>> and the emitter it should be completely turned off)
>>
>> U04 pin 07 is 4v and on the other side of r17. U06 pin2 is 0v U06 pin1
>> is -1v The Pitch CV out is -1v
>> Q04 pin1- 0v
>> 2 -.08
>> 3 -.5v
>> 4- -.5v
>> 5- 0v
>> 6- 0v
>> I feel like the part of the circuit that drives c05 works but that
>> somehow it's never pushe to the 4th step of moving the c05 voltage to
>> c06? It seems like u04 pin7 should fluctuate like u04 pin1. Thanks
>> again. Joe.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Simon Brouwer wrote:
>>> Hi Joe,
>>> About the same voltage as on U04 pin 1 (i.e. dependent on the
>>> frequency) should be present on U04 pin 7, is it?
>>> With a positive voltage at U04 pin 7 it is strange that you get a
>>> positive voltage at the output, since the current going via R17 into
>>> pin 2 of U06 would cause U06 pin 1 to go negative (there should be no
>>> current going into Q04 (left) collector since with 0V at both the base
>>> and the emitter it should be completely turned off)
>>> If the output were stuck to a negative voltage I would suggest
>>> adjusting P02. I expect a normal voltage of around 0V at the base of
>>> Q04 (right), and around -0.5V at the emitters.
>>> But if the output is stuck to a positve voltage something else is
>>> wrong that has to be resolved first.
>>> Best regards
>>> Simon
>>>
>>> > Op 28 juli 2014 om 4:50 schreef Joe Frey <joe.frey at radioles.com>:
>>> >
>>> >
>>> > Simon, Thanks! Well, at very least you helped me feel like I might
>>> get
>>> > this going with help from bigger brains than mine.
>>> > As cheater00 pointed out, I didn't state how it wasn't working. I
>>> > only get a steady 5.3V at pad 4(Pitch CV). It does not change.
>>> >
>>> > > apply +12 V to PAD7, I wonder if the voltage on U04 pin 1 goes to
>>> > > around 0V (I think it should). If it does, leave PAD7 open again
>>> for
>>> > > the next check,
>>> > I did this and pin 1 of U04 went to 0V!
>>> >
>>> > > - if you apply a continuous input signal, do you see the DC voltage
>>> > > (as measured with a multimeter) of U04 pin 1 go down from the 11.4V
>>> > > that it is without input signal? Does it come closer to 0V at
>>> higher
>>> > > frequencies of the input signal?
>>> > Yes. U04 pin 1 I get .004-7.0 volts with the smaller values at higher
>>> > frequencies.
>>> >
>>> > Thanks. Again. Can you tell me where to look next? Joe.
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> > Simon Brouwer wrote:
>>> > > Hi All,
>>> > >
>>> > > Apparently the gate signal is stuck to "on". I don't understand how
>>> > > this part of the circuit is supposed to work, how can the gate
>>> signal
>>> > > ever go off if there is no input signal? Since in that case U07B is
>>> > > not getting clocked and will not change its output state...
>>> > >
>>> > > And Joe,
>>> > >
>>> > > For some first checks,
>>> > >
>>> > > - apply +12 V to PAD7, I wonder if the voltage on U04 pin 1 goes to
>>> > > around 0V (I think it should). If it does, leave PAD7 open again
>>> for
>>> > > the next check,
>>> > >
>>> > > - if you apply a continuous input signal, do you see the DC voltage
>>> > > (as measured with a multimeter) of U04 pin 1 go down from the 11.4V
>>> > > that it is without input signal? Does it come closer to 0V at
>>> higher
>>> > > frequencies of the input signal?
>>> > >
>>> > > Best regards
>>> > > Simon
>>> > >
>>> > >
>>> > >
>>> > >
>>> > > Joe Frey schreef op 27-7-2014 19:00:
>>> > >> The PV-1 is a pitch to voltage converter designed by Harry Bissel
>>> and I
>>> > >> know of one person that uses it.
>>> > >> Needless to say mine doesn't work and I'm stuck. I have added a
>>> link for
>>> > >> the original project pdf that has the schematic. There is a link
>>> to a
>>> > >> pdf of my project with voltages listed for ICs, transistors and
>>> diodes.
>>> > >> There are links to a photo of the top and bottom of the board I
>>> made and
>>> > >> populated, Any help would be much appreciated.
>>> > >>
>>> > >> http://www.radioles.com/works/pv1_611-1.pdf
>>> > >>
>>> > >> http://www.radioles.com/works/PV-1%20trouble%20shooting.pdf
>>> > >>
>>> > >> http://www.radioles.com/works/IMG_20140724_230152028.jpg
>>> > >>
>>> > >> http://www.radioles.com/works/IMG_20140724_230201823.jpg
>>> > >>
>>> > >
>>> > >
>>> >
>>> >
>>> > --
>>> > ("> <")
>>> > / ) ( \
>>> > ''/ | / |``
>>> >
>>> > "Anything worth doing, is worth doing badly, because it might make
>>> it better the next time." --anon
>>> >
>>> > Joe Frey
>>> > A.K.A. Bitter Relic of a Bygone Era
>>> > joe.frey at radioles.com
>>> > http://radioles.com
>>> > Chez Judex
>>> > http://radioles.com/judex/
>>> > Radio Lu-Lu (Internet radio)
>>> > http://radioles.com/radiolulu/
>>> >
>>> >
>>> > _______________________________________________
>>> > Synth-diy mailing list
>>> > Synth-diy at dropmix.xs4all.nl
>>> > http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>
>>
>
>
--
("> <")
/ ) ( \
''/ | / |``
"Anything worth doing, is worth doing badly, because it might make it better the next time." --anon
Joe Frey
A.K.A. Bitter Relic of a Bygone Era
joe.frey at radioles.com
http://radioles.com
Chez Judex
http://radioles.com/judex/
Radio Lu-Lu (Internet radio)
http://radioles.com/radiolulu/
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