[sdiy] Re: quantizer

[peter edwards]

Hello Ray,
I'm sorry for being so persistent with this. I'm playing a show in a  
few days and I would really like to use these modules
I'm using banana jacks...and the out jack is wired to "VOUT" on the  
board. There's no chance that I wired the out to ground. I suspect  
otherworldly sabotage, cause this doesn't make any sense. Maybe a  
priest or the ghost busters would have better luck at fixing this ;-)
I keep thinking that the fact that both units are malfunctioning in  
the same way is telling. maybe I'm using some bad components. The ICs  
are all brand new from Mouser. I just got a new batch of .1uf caps.  
they are smaller and cheaper than the ones I usually use.. rated at . 
1uf 50V 20%. I don't think this is the problem, but I'm running out  
of ideas. one other thought is that I am using a possibly unwise  
method of connecting my modules to power when I test them. I have a  
stereo jack mounted on my main modular synth. this jack delivers +- 
ground. I use a stereo patch cable to plug it to a stereo jack on the  
module I am working on. Once the module is done I use the standard  
power bussing methods, but while I'm working on them this is easier.  
The only "problem" with this method is that when you plug the cord in  
it briefly short out some of your power rails. The best thing to do  
is shut off power, plug in the stereo cable, turn power back on. but  
I'm often too impatient for that :-p   This has NEVER been a problem  
with any module I've worked on, but maybe the quantizer didn't like  
it and I fried some chips????? I don't know. are any of the ICs in  
the quantizer especially extra delicate? I'd like to avoid buying a  
whole new set of chips because I don't think they are the problem.  
The LFO feeding through to the VCO is weird.
On Jan 8, 2009, at 5:44 PM, Ray Wilson wrote:

> Hi Pete
>
> Reading below you indicate that with no power the LFO passes  
> straight through to the VCO. This should not be occurring. It leads  
> me to suspect the jack wiring. If the output is mistakenly going to  
> the jack ground the chip will most likely get hot and you will get  
> nothing out of the unit. It could also cause the odd "power off"  
> behavior you are seeing.
>
> Ray
>
> ----- Original Message ----- From: "peter edwards"  
> <synth at casperelectronics.com>
> To: "Ray Wilson" <raywilson at comcast.net>
> Cc: "sdiy DIY" <synth-diy at dropmix.xs4all.nl>
> Sent: Thursday, January 08, 2009 3:02 PM
> Subject: Re: quantizer
>
>
>> Hello Ray and everyone else who has responded, Thank you for the  
>> input!!
>> I am using an HCF4013 on one of the circuits and a CD4013 on the   
>> other. both aren't working. I believe that both should work with   
>> 15volt supplies.
>> The first quantizer I built I made a mistake with the power   
>> connection and it was only getting ground and -15v.... no +15.  
>> Then  the TL074 burned... so I assumed it the missing +15 was the  
>> cause ...  even though that seemed strange. So I fixed the power  
>> and replaced  the TL074.. same problem. then I replaced each chip  
>> one at a time  with no change. THEN I built the second one and  
>> it's the same problem  with the new circuit... there is no voltage  
>> output and the TL074 gets  hot and burns if I leave it hooked up  
>> too long.  I have it configured  so that I'm feeding an LFO(from  
>> the sound lab) going to the input and  the out is going to the  
>> sound lab VCO1 CV input. WHen the quantizer  circuit is NOT  
>> powered, the LFO passes straight through to the VCO.  When I apply  
>> power to the quantizer, the output of the quantizer goes  to  
>> zero. . . all of the chips are in the correct orientation.. the   
>> power is hooked up correctly and I have have a good, clean power   
>> supply of exactly +&-15vdc.
>> -pete
>>
>>
>> On Jan 8, 2009, at 10:00 AM, Ray Wilson wrote:
>>
>>> Hi Pete
>>>
>>> I have sold quite a few of these boards and no one has reported a  
>>> problem and mine works fine as well. If the supply is reversed  
>>> or  the chips are in backwards they will get really hot (and  
>>> need  replaced). Other than that I can't think of what could be  
>>> causing  the issue. Are the chips socketed? If so were the  
>>> sockets oriented  correctly? If not are the chips oriented  
>>> correctly. Check that  first and let me know what you find.
>>>
>>> Also you must use CD40XX CMOS chips and not 74HCXX or other high   
>>> speed types because they have power supply limitations. Far more   
>>> unlikely but possible that both TL074s were bad. All of the  
>>> chips  in the circuit are spec'd for up to 15V. Is your supply  
>>> putting out  more than that?
>>>
>>> Do they only get hot when you are connected to another module?  
>>> What  is the resistive load you are driving? Is the output jack  
>>> wired  correctly. If you are putting the output to a hard ground  
>>> I could  see the chip getting hot and you getting no output.
>>>
>>> Let me know what you find.
>>>
>>> Ray
>>>
>>>
>>>
>>>
>>> ----- Original Message ----- From: "peter edwards"  
>>> <synth at casperelectronics.com>
>>> To: "Ray Wilson" <raywilson at comcast.net>
>>> Sent: Thursday, January 08, 2009 3:19 AM
>>> Subject: quantizer
>>>
>>>
>>>> Hello Ray,
>>>> I just built 2 quantizers at the same time and they both do not   
>>>> work. When I plug them in the TL074 IC gets hot. It's the same  
>>>> on  both.
>>>> I have a good deal of experience building modules, so I don't   
>>>> think this is an obvious blunder. I'm using the specified ICs.  
>>>> I  don't get it.
>>>> Have other people had problems??
>>>> thanks!
>>>> -pete
>>>
>