Rebote 2.5 PT2399 Question

[Phend]

Hello
Just finished the Rebote 2.5. It works and sounds like the demos on tube.
Checking voltages I noticed a difference in the limited references I have found.
It involves Pins 5, 7 and 8. So in that order:
Reference 1
2.56
0.19
0.78
Reference 2
3.40
0.20
0.70
Mine
3.50
0.66
0.78
Here is the question.
What does Pin 7 do and is 0.66 ok vs 0.20 ?
I believe 7 and 8 are clocks ?
Does it matter that Pin 7 is high ?
Circuit is simple off Pin 7, just a cap to g.
(Batt 9.4, Supply 5.09)
Thanks in advance

[Ripthorn]

Pin 5 doesn't matter. Pins 7 and 8 are modulator and demodulator caps. If it sounds and behaves right, I wouldn't worry to much about the voltages.

[Locrian99]

My pt2399 delay (deep blue delay clone) didn't match the listed voltages either it works fine.  If I remember correctly they are pretty close to what you show. 

[soggybag]

I built a Rebote 2.5 10 or more years ago. I was just comparing it to the Aquarius. I like the sound of the Rebote better. The delay time is a little longer and the filtering on repeats has nice sound.

The Aquapus beats the Rebote on noise.

[anotherjim]

Pins 7 & 8 are explained as far as can be (we don't have the internal circuit in detail).

Pin 5 is useful to detect if the chip is running or has locked up. If running, there is a full swing square wave on pin 5. Ideally, a good square wave has an average DC level halfway between its high and low periods. So if it switches between 0v and 5v the average is 2.5v and that is what a DMM on DC voltage might be expected to show. However, it's also a high frequency and can reach about 20Mhz at the shortest delay time settings. At those kinds of speeds, the self-inductance and stray capacitance among the circuit and test equipment probes & leads affect the quality of the squarewave. It will have "ringing" peaks and looks like this...

The positive and negative ringing exceeds the 5v supply and if it amounts to a 7v total between peaks then the average tends to rise above 2.5v.
Ringing isn't the only way the voltage moves away from 2.5v. If the waveform spends different times in high or low switch periods that is, not a perfect 50% duty square wave, then the average may be higher or lower. I suspect this may happen when the pin 6 resistance is at the lower limit it can work with.

So you cannot absolutely say much about pin5 DC voltage readings except that if it's closer to 0v or 5v, then there probably isn't a squarewave because the delay clock isn't running.

Note that this 2.5v on pin 5 has nothing to do with the 2.5v DC expected on pin 2 and the audio path pins.

[ElectricDruid]

Pin 5 doesn't matter. Pins 7 and 8 are modulator and demodulator caps. If it sounds and behaves right, I wouldn't worry to much about the voltages.

+1 agree with what Ripthorn and Jim said. These pins have high frequency AC signals on them, and taking a DC measurement isn't really going to tell you anything much.

[Phend]

Thanks all for the replies.  Now I will wire up the "Astro" switch.
Re : Deadastronauts chorus 1M mod between pins 6 and 8.

[Phend]

PT2399 Pin 1, as seen in post 1 picture above, has two 47uF caps in parallel.
Any idea why a single 100uF cap was used there at pin 1?
Edit:
Just looking at the data sheet, yes a 100uF cap is at pin 1.

[PRR]

two 47uF caps in parallel.

Someone was buying 47-mic caps in bulk.