[sdiy] Re: quantizer

[Ray Wilson]

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
>>
>