SV: Re: [sdiy] Buchla 100 oscillator - bad ua726?

[mark verbos]

Grant Richter suggested that it was a bad pot. In a Buchla 100 when you 
switch to external CV mode, there is no pot in the equation, besides the 
one on the module connected to it, in this case the 256 was doing fine 
with the other oscillators.

While I had replaced the initial frequency trim already, I had not 
replaced the trim that the external CV goes through before the uA726, so 
today I replaced it with a fixed resistor and the problem went away. So 
I guess it was a pot after all!


Thanks Karl and Grant,


Mark





karl dalen wrote:
> Another idea is to measure the ovens current consumption
> and if that fluctuates the slightest then the VCO will go out of tune.
> Resistor on pin6
> 
> What about the oscilator ballance pot? If its crackling
> it would affectsymetry and to much crackle the osc will detune!
> 
> Dentist indeed! 
> 
> KD
> 
> --- Paul Perry <pfperry at melbpc.org.au> skrev:
> 
> 
>>Since the function of the ua726 is to regulate its own
>>temperature (and thus the temp of the transistors in it)
>>maybe you could try putting you finger on it (to heat 
>>it up or down) and seeing if anything changes.
>>A lot of electronic diagnostics is like dentists, just
>>prod and probe until the scream.
>>
>>paul pery melbourne australia
>>
> 
> 
>