# Super heterodyne receiver issue



## Dazoner (May 10, 2019)

Hi.  Does anyone have the voltage measurements for the IC's.  I have this awful high pitch squealing that I'm having a hard time tracking down.  Thanks.


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## Dazoner (May 11, 2019)

I think the squealing us coming from the oscillator side of the circuit.  I can't confirm as there's no schematic for me to verify exactly which components.

Any help would be greatly appreciated.


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## Bonair (May 17, 2019)

High pitched squealing could be caused by quite a few different things. Isn’t there an opamp in this (tl072?), maybe try swapping it first and even checking orientation of all ic’s and electros. Or you can possibly use an audio probe if you think you know where the squealing is coming from and want to confirm.
   I haven’t built this but I believe it’s a data corrupter type thing? If so, it seems like it might be a pretty big ask to get someone to post the hundred or so ic measurements you’re requesting. You should post all of yours for people to take a look at them to try and help.


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## zgrav (May 17, 2019)

If it has a charge pump, see if pins 1 and 8 are connected.


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## xixaro (Jun 29, 2019)

Dazoner said:


> Hi.  Does anyone have the voltage measurements for the IC's.  I have this awful high pitch squealing that I'm having a hard time tracking down.  Thanks.



Hello,
I am experiencing exactly the same issue as you.
I have to turn down the Oscilator Pot, otherwise it is impossible to use the pedal with this "high pitch" sound, which take-off with the first note played.

I changed all the IC one by one, testing the result, and I am still having the same "high pitch",
I noticed that when the CD4046 is removed the pitch is gone.
All the electro. caps are in the right polarity and all the ICs, T072 included, are in the right position.

Any suggestions about what to try next, please?

Thank you,


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## xixaro (Jul 1, 2019)

Hello,
I am experiencing exactly the same issue as you.
I have to turn down the Oscilator Pot, otherwise it is impossible to use the pedal with this "high pitch" sound, which take-off with the first note played.

I changed all the IC one by one, testing the result, and I am still having the same "high pitch",
I noticed that when the CD4046 is removed the pitch is gone.
All the electro. caps are in the right polarity and all the ICs, T072 included, are in the right position.

Any suggestions about what to try next, please?

Thank you,


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## Robert (Jul 1, 2019)

Where did you get the DPDT toggle switch?


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## Dazoner (Jul 2, 2019)

Hi,

I can't speak for Xixaro. But I tried to build two of these pedals and neither are working properly.  I tried subbing all the IC's between them and no changes.
As for the dpdt switch, I got mine from Small Bear.  I'm not at home right now but I can check the switches again for proper functionality, but I'm pretty sure I've gone over everything 3 times already.

Let me know is there's anything you'd like me to check.


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## xixaro (Jul 2, 2019)

Robert said:


> Where did you get the DPDT toggle switch?


Hello,
I got mine from tayda


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## chongmagic (Jul 2, 2019)

I have built two of the supers and one mini with no issues. I don't think you can get the proper toggle switch from Tayda. It has to be Smallbear or Mouser.


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## xixaro (Jul 4, 2019)

Well,
thank you for your replies.
That may help indeed.
In Europe there are little chances to procure items from smallbear or mouser, therefore tayda and musikding remain the main suppliers.


General picture for switches position alignments:




Notice that in the picture above, the "DPDT on-on-on 1" is actually the smallbear "DPDT on-on-on, solder term" - named "type 2" by pedalpcb.

The smallbear "DPDT on-on-on, solder term":
http://smallbear-electronics.mybigcommerce.com/dpdt-on-on-on-solder-term/ 





and the same applies to the lovemyswitches "DPDT on-on-on":
https://lovemyswitches.com/taiway-dpdt-on-on-on-switch-solder-lug-long-shaft/ 





This induces some confusion about what is "type 1" and "type 2" positions, as for instance when you procure the the "DPDT on-on-on" from Tayda and/or Musikding they sell a "type 2" which is actually not the "type 2" pcbpedal is mentioning.

Therefore,
the right alignment for the "Super Heterodyne Receiver" pedal, when the toggle is in centre position, shall be the following,
as per what is written in the "PedalPCB-SuperHeterodyneReceiver-BOM.pdf" file, named "DPDT on-on-on type2":





--------------------------------------------------------------------------------

At Musikding this switch is named "type 1" 
https://www.musikding.de/Toggleswitch-DP3T-ON-ON-ON-Type-1




At Tayda they only sell a "DPDT on-on-on" that is tagged "MTS-2", I guess that "2" stands for "type 2". This switch has the following alignment when the toggle is in centre position:




Thank you.


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## Dazoner (Jul 4, 2019)

I just had my Homer moment.  I installed type 1 dpdt switches instead of type 2.  I'll update once I get the parts.


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## Robert (Jul 4, 2019)

Dazoner said:


> I just had my Homer moment.  I installed type 1 dpdt switches instead of type 2.  I'll update once I get the parts.



Does it function normally with the DPDT in the Up or Down position?      The wrong type switch should only affect the Center position.


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## Dazoner (Jul 6, 2019)

Yes, the switch does function normally.  But once I engage the oscillator side of the circuit, it just screams.


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## xixaro (Jul 7, 2019)

Hello,

I have more information to share with you.

I have removed my "DPDT on-on-on" from the pcb. This makes the high pitch to vanish, indeed.

My "DPDT on-on-on" has the following centre alignment, which actually does not match the one required in the BOM,




Now,
I have installed the very same "DPDT on-on-on" on the top side of the pcb, as in the picture here below. Before, the swich was installed, welded, on the pcb bottom side, of course.
Any guess about what happens then?




R. : the noise, high pitch tone, is back!
Hence, it seems the issue is not fully related with the switch being "type 1" or "type 2".

Would you please share, when available, the pcb circuit diagram?

Thank you.


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## zgrav (Jul 7, 2019)

aside from the noise that you are trying to isolate, did the pedal operation change after you mounted the dpdt switch on the other side of the board?


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## xixaro (Jul 7, 2019)

zgrav said:


> aside from the noise that you are trying to isolate, did the pedal operation change after you mounted the dpdt switch on the other side of the board?



Not that I noticed, the high pitch noise remains in either side.


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## Robert (Jul 7, 2019)

I'll get the schematic up for you ASAP.


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## Hexjibber (Mar 10, 2020)

I’m also having an issue with the oscillator creating a high pitched note, was it ever discovered whether the issue was related to the switch? Trying the check the Taiway part number with Banzai but will try and order one from Love My Switches if it turned out to be the cause.


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## Hexjibber (Mar 12, 2020)

An update on my issue; I heard back from Banzai who informed me the part number for the switch I've used is M305DX-NI (Nickel), a quick Google only turned up scant results but that part number was listed on a Russian site with this diagram:



This would appear to follow the correct switching type as detailed earlier in the thread, could the high pitched tone I'm getting be related to something else? I've ordered the exact switch from Love My Switches so will swap that out anyway as a matter of course but just concerned it may not be the answer.

The only other issue I can describe is that I initially had ordered and installed a CD74HC4046AE (it was the only 4046 Banzai had in stock at the time) which was causing some strange clicking noise when turning up the Oscillator, once I realised my error I replaced it with the CD4046BE but this is when the high pitched note issue was introduced.

I've checked the usual orientation stuff, ICs, electro caps etc but am fairly certain everything is as it should be on that front. Will check again just to be sure though.

Could really use some input on this one if any one can help?


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## Dazoner (May 10, 2019)

Hi.  Does anyone have the voltage measurements for the IC's.  I have this awful high pitch squealing that I'm having a hard time tracking down.  Thanks.


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## zgrav (Mar 12, 2020)

why not switch back to the cd74hc4046AE chip to see if your original problem with the oscillation returns and the high pitched noise goes away?

that at least will show the underlying issue has not changed.  maybe it is the chip, or at least a part that is related to the operation of the chip.


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## Hexjibber (Mar 13, 2020)

zgrav said:


> why not switch back to the cd74hc4046AE chip to see if your original problem with the oscillation returns and the high pitched noise goes away?
> 
> that at least will show the underlying issue has not changed.  maybe it is the chip, or at least a part that is related to the operation of the chip.



Hi,

Thanks for the reply, I swapped back to the other IC and my original issue of getting a weird clicking sort of sound returned, in both cases the oscillator doesn’t work as I expect or sound like the videos I’ve watched.

Would be great if the OP of this thread could tell me whether they ever solved the issue and how as the symptoms sound identical.

Will post an update once the new switch arrives from the US and I’ve swapped the old one out.


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## Hexjibber (Mar 17, 2020)

Update on my issue:

I received the new switch from LoveMySwitches, alas it has made zero difference, the constant high pitch note from both the subharmonic and the oscillator remains 

I have checked and re-checked my part orientation but as yet cannot see an issue. The fuzz sound seems to function perfectly, it’s only when turning up the sub or osc that I get the high pitched tone/note. Removing the 4046 stops the sound so I presume it is related but I’m getting nowhere really.

Does anyone have any ideas of things to try or potential causes of this issue? Built this for a friend so am keen to get it working. Any help greatly received!

Have attached a photo for reference


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## Hexjibber (Mar 17, 2020)

Ok another quick update, sorry! I've just been scouring the build and noticed one of my CD4017BE chips is actually a CD40174BE which as far as I can tell from the data sheets is not the same thing! Thanks Banzai! Ordered another CD4017BE, fingers crossed!


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## tcpoint (Mar 17, 2020)

That would do it.


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## BlackNinja (Mar 22, 2020)

Hi all !
I have been experiencing the same problem with the oscillator voice and I might have some more input : I've been audioprobing a bit of the circuit and observed that the signal is coming "unaltered" (fuzzy) into the 4046 through pin 14 BUT what comes out of it (pin 4) is the infamous squealing noise. When I remove the 4046 the noise disappears as well, but of course i get no oscillator voice. So it seems to me that the 4046 might be faulty. Gotta try to get a few fresh units for swapping. I'm in Europe also and Musikding have some in stock so I guess I'll be able to give an update quite soon.
Since then, stay the f*** home guys 
Cheers


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## Hexjibber (Mar 26, 2020)

Hi all, hope everyone is keeping well out there! 

Just to update on my progress with this, finally took delivery of another CD4017BE to replace the incorrect CD40174BE I received from Banzai, and hallelujah it works perfectly! So chuffed! Obviously an obvious lesson there for me, check, double check and triple check those parts! I feel like I'm normally pretty meticulous but just goes to show it can happen at any time! 

Anyway, now that's sorted I can breathe a sigh of relief, build report coming soon!


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## xixaro (Jul 4, 2020)

xixaro said:


> Hello,
> 
> I have more information to share with you.
> 
> ...



Hello,

12 months after my initial thread about the high pitch noise,
I finally managed to have some spare time to tackle the problem.

So, the 1P8T oscillator switch had some construction flaw, which was at the origin of a missing contact inside the switch, producing the oscillator high pitch!

Issue solved!


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