OKKO DIABLO + QUESTION

[djmiyta]

The build docs call for TC1044scpa I have a 7660cpaz and although it powers up and passes signal there is a whine there and I did the 39k resistor and 10nf cap mod. Would using the 7660 be another possible cause for the whine?

 

[jimilee]

The build docs call for TC1044scpa I have a 7660cpaz and although it powers up and passes signal there is a whine there and I did the 39k resistor and 10nf cap mod. Would using the 7660 be another possible cause for the whine?

Read the data sheet to make sure they have the same pinout.

 

[Cybercow]

Both the TC1044SCPA and the ICL7660CPAZ have the same pinouts. And both operate at 10K Hz in "non-boost" mode. In boost mode (pin #1 & pin #8 connected) the TC1044SCPA operates at 45k Hz, while the ICL7660CPAZ operates at 35K Hz. In boost mode, both operate at well above the audio threshold. Make sure pin #1 & pin #8 of the chargepump are connected.

I'm unaware of the "39k resistor and 10nf cap mod" . . . . what is that please?

 

[Robert]

I don't believe 7660CPAZ has the boost function, you'd need 7660SCPAZ.



Which PCB do you have, the older 1590BB or the newer 125B version?

 

[Cybercow]

I don't believe 7660CPAZ has the boost function, you'd need 7660SCPAZ.

View attachment 45762

Which PCB do you have, the older 1590BB or the newer 125B version?

Clearly there are data sheets that bear conflicting information. The 7660CPAZ I looked up on Mouser clearly shows pin #1 as a "Boost"

 

[Robert]

Sometimes they share the same datasheet (at least this one does):

https://www.mouser.com/datasheet/2/698/REN_icl7660s_a_DST_20121024-1997724.pdf

The S suffix denotes "Super", which is the frequency Boost function. Without the S suffix you're likely going to have oscillator bleed into the signal path. Not always, because I have seen a few pedal circuits that run at 10KHz without any negative side effects, but we've also seen a few cases where the proper (S) charge pumps cause whining as well.... in those cases swapping the charge pump usually corrects the issue.

We've also seen a few cases where a datasheet was incorrect, oddly enough. The Interfet J201, for example, lists the pinout incorrectly (although irrelevant since the drain/source are interchangeable).

 

[music6000]

The build docs call for TC1044scpa I have a 7660cpaz and although it powers up and passes signal there is a whine there and I did the 39k resistor and 10nf cap mod. Would using the 7660 be another possible cause for the whine?

It should read 7660SCPAZ or it will whine, I use this chip in all my Builds that require TC1044SCPA's & I have never had an issue!
I can't say the same about the TC1044SCPA & Members here have been burned by counterfits of it!
The TC1044SCPA has been used successfully here if purchased from a reliable source & is widely used in the pedal industry!!!

 

[Feral Feline]

I read somewhere, probably on Barry's site (GPCB) about making sure to get the 7660SCPAZ, gotta have the "S" — also read that MAX1044's tend to blow up, but the legit TC1044SCPA I've never read about problems.

 

[djmiyta]

Thanks all for the insight. Unfortunately changing the charge pump to spca only quieted it down so Ill try a scpaz and see how that goes
I don't recall where I found the mod might've been here on this site but here's what I have . I believe it was supposed to help with the whine .

 

[music6000]

Thanks all for the insight. Unfortunately changing the charge pump to spca only quieted it down so Ill try a scpaz and see how that goes
I don't recall where I found the mod might've been here on this site but here's what I have . I believe it was supposed to help with the whine .

Is this the current PCB or Version one?