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Messages - Robusto

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1
I have come back to end this thread and accept my badge of shame. Yes, I did have a matched set of JFETs. Unfortunately they were 2N5952s that I got from guitarpcb.com and I forgot to invert them on the board. Case closed.  :-[

2
Hello,

I am working on the latest version of the NomNom (Phase 90). I am getting a clear signal when engaged but not phasing. I have been through the board with an audio probe and the clean signal/rate pot section seems to be the problem. I have signal at the emitter of Q1, but when I move on to R25, and the other spots in that section (including the right side of IC1), I get a faint heartbeat type flopping noise that speeds and slows when I adjust the pot. The left side of IC1 is passing signal as normal, along with all the other two ICs. I've tries adjusting T1 with no change. Voltages seem okay. I've tried 4 different TL072s in IC1 with no change. Hoping this is a common thing that someone will notice right away. Thanks!

1 Spot power supply at 9.42v

On all three ICs  1-3 and 5-7 are  3.85v, 4 is 0 and 8 is 9.16
Q1 is 2.27C 2.8B 3.85E
Q2-5 all three pins are at 3.85 or very close to it


 

3
Latest Update:


4
I got the 8038 on eBay from here:

https://www.ebay.com/itm/2PCS-INTERSIL-ICL8038CCPD-ICL8038-Waveform-Generator-Oscill-Gen-DIP-14-IC-New/291565457594?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Looks like they're still in business with a 99.8% rating, although the top review says "Counterfeit ICís all 5 where bad. Replaced with another vendors product all work
5PCS National Semiconductor LF351N LF351 JFET Input Op-Amp and Machined"
Sooooooooo.....hmmm. I bought two of them and have tried both.

I got the AD633 from Mouser.

Sounds like maybe the 8038? Would be nice to have one from a legit source. Does anyone besides Small Bear sell them?

Thanks for the reply!

5
Ok, nothing? Here’s some more:

I reseated all the ICs. I changed out the shift and mod pots for new, as the first ones I used had been salvaged from a previous project. I started tracing with an audio probe and started getting an effect signal all the way to the end. I plug a guitar into it and I am getting effected signal, but the pots have no effect. The signal stays the same no matter which way I turn them.

Annoying.

6
Hey all,

As the title says, I finished the Freekout, and when engaged, I'm getting a boosted signal but no modulation. I can hear the whine of the generator, and it goes up and down if I adjust the pots, but no effected signal.

Checked all the part values, I don't see any solder bridges, here's the voltages:

Input 18.06V
Trim 50%
Pots all fully clockwise

IC1
683mV
35mV
35mV
-14.46V
38mV
38mV
38mV
14.37V

IC2
-1.3mV
.58mV
-16.5mV
.58mV
-14.5V
4.1mV
0
14.87V

IC3
8.8V
7.38V
7.49V
11.76V
11.75V
14.87V
11.7V
11.7V
7.8V
7.53V
.56mV
5.64mV
_
1mV

IC4
0
1.3mV
0
-14.5V
2mV
2mV
2mV
14.87V

IC5
-14.49V
-6mV
-4.9mV
-14.5V
-14.5V
-4mV
14.87V
_

IC6
1.9V
7.97V
.7mV
-6.64V
-14.5V
2.5V
1.4V
14.8V

REG
17.74V
.36mV
14.87V








7
General Questions / Odd Current Lover output issue
« on: December 24, 2019, 12:06:43 PM »
Hello,

Finished the Current Lover recently. Worked great unboxed. After I boxed it, the effected part of the signal went away. So just clean signal with the effect engaged. After some messing around, I discovered that there is some issue with the in/out jacks. The problem is happening when the jacks are installed in the box. If i unscrew them and hang them off the side of the box, the effect comes back. I've tried different jacks. This enclosure is unpainted. Am I grounding/shorting the board with the jacks touching the metal? It doesn't seem to make a lot of sense. I thought about trying to cover/paint the inner edges of the holes for the jacks, but what would I use? Thanks!

8
Mods / Re: Current lover - Rate LED?
« on: December 10, 2019, 08:06:04 AM »
Not sure if i should make a new thread for this or bring this one back from the dead, so I'll start here. I just finished the Current Lover, and my rate LED only blinks when the pot is almost fully clockwise. From 0%-95%, it stays solid. Do I need to experiment with the value of R36 maybe? The clock trim? Has this issue ever been reported before?

Thanks!

9
General Questions / Current Lover question
« on: November 29, 2019, 01:35:37 PM »
Loved building this, and it actually worked the first time I plugged it in!

Question: as I am adjusting bias, around the mid-point there's a ton of distortion. Is this normal? I have to set the bias trim to 100% to get flange, and it's still kinda noisy. Is there a chip i should try swapping out to see if that makes a difference? I bought my BBD from Small Bear, so should be legit.

If anyone has any tips, let me know.

Thanks!

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