Madbean NomNom with Depth and LERA

[Shaggy45]

Thanks mao.

i get no phaser sounds, only clean. i noticed today i had two resistors in the wrong holes but that didn't
get me any phaser sounds. i'll keep looking at it and see if i misplaced anything else. i'll bust out my meter and sound probe when i get more time.

[Shaggy45]

ok if i turn the speed up i can here a thumping sound and when i engage the lera i can here it speed up or slow down (which ever mode its in) and for like half a second when i flip the lera switch i here phaser..so close..i can feel it. any suggestions based off of this info? or should i post voltages. maybe i should go back and double check my resistor values and make sure i didn't mix them up. i went back and knifed the board and no luck there. all the wires are in the right spots. when ever this thing works its gonna be awesome. functions like my ap-5 and ap-7 jetphaser


also i'm using 2n5952 quad set from guitarpcb

Edit:

Just realized the pin out is different on the 2n5952. so i swapped them around. now i get clean sound with
the lera off with no thumping and no sound with the lera on unless i pluck really hard and then i get a short loud distorted sound.

[MAO]

Ah shoot, the layout has the pinout for the 2n5952, not the 2n5957. So flip your 5952s back around. Sorry, ill update the layout asap.

 But now I'm intrigued,

On a regular phaser, I've had an issue with the speed pot connection causing an abrupt halt to the phasing, but in this design that would only happen in the non-lera mode. Wouldn't hurt to check that the speed control connects properly though when the Lera switch is set for phase.

But given you can hear the ramp up and down, sounds like the lfo is working.

Maybe the strait signal isnt making it through? Check the horizontal 150k and the cut between the bias trimmer and the link to its right.

If needed, I'll build one too so we can compare notes/voltages.

[Shaggy45]

rechecked the wiring. checked resistor values and cap values. checked jumper locations and cut locations.
checked diode and cap orientation. re flowed the board and cut it again. Still the same. bummer. i don't want to give up though. I'm sure it's something simple. it usually is.

[MAO]

Sorry to hear that, i'll try to build one tomorrow so we compare, think I have everything i need.

I'm still thinking something is up with the mixing in of the strait signal since you could hear the thumping and ramping up/down.

In the meantime, can you post the voltages off the transistors and ics?

[Shaggy45]

if i connect a led to pin 1 of the 358 it will fade in time with what i have the knobs set and will change back and forth when i click the up/down button (all in lera mode). if i use the led on the tl072's i just get a solid light and no blinking or anything. Also i can only here the thumping with the lera off if i have the speed set really high.

i'll try to get some voltages sometime today

[MAO]

hmm, that's a good clue. Sounds like the LERA is doing it's thing.

Let's check the original LFO:

So with the LERA switch off, pin 7 of the  LM358 should also cause the LED to change intensity in unison with the Speed control. And so should Depth-2.

If the LED does follow along with the Speed control, then jump down to check #2. But be sure power is disconnected and LERA Switch is off for the following checks.

Assuming the LED is not lighting or changing intensity, 1st double check that all the switch connections and Speed lugs are properly wired up. If they check out, then start with check #1

Check 1. If you have a meter handy, with power turned off or disconnected, and the LERA Switch off, measure the resistance between pins 6 & 7 of the LM358, see if it changes when adjusting the Speed control. (you may need to remove the IC). If not, then the issue is probably something with the Switch and/or Speed control section.  

Check 2. If check #1 was ok, then measure the resistance between the grey-colored jumper and the top of the 3M9. Should be between 700k and 1M2 depending on where the Depth control is set. (may need to remove the jfets to get a proper reading).

[GrooveChampion]

To what degree are the Opamps interchangable? I dont have a 358(or a matching Jfet set, but whatever)

[MAO]

Unfortunately for this design you need the LM358 (according to the designer RG Keen) and matched jfets. 2n5952s or 2n5457s.  

You can match your own jfets, but time consuming and you need to buy at least 25, maybe more to get a good matched quad.  Better off just buying a matched set from a known source like here. tayda has the LM358s.

But, I wouldn't buy anything just yet if it's for this build as we need to get it verified 1st.

[Shaggy45]

i'm not sure why i typed pin 1. it's pin 7. it does react to the speed control with lera turned off. the sweep is wrong though. it doesn't seem to do anything until it's almost all the way up. i'll do the checks you mentioned when i get home from work in the morning. thanks for your help mao

[MAO]

OK, I built it today and to my surprise it fired right up!

Both the LERA and the original LFO are working.  

First though, thanks to notnews for originally bringing up the LERA, and to Shaggy45 for drumming up some interest. And of course to R.G. Keen for his genius.    

The only issue I found with the layout is the Ramp Speed wiring needs to be reversed. edit - And the max speed isn't as fast as my other Nom-Nom. edit-edit maximum Speed corrected, I had installed a 100u instead of the proper 10u.  

I also tweaked the layout I actually built just a little, but I'm sure the one that is posted is OK as I didn't reference a schematic when I made the changes, I just moved a couple things around.

And for anyone else thinking of building this, if you already have a working Phaser, and someone that can turn the speed knob while you're playing, you can easily simulate what the LERA does and see if it's something you'd like.

In a nutshell, the LERA allows you to alternate between two preset speeds, slower and faster, using a stomp switch. The Hi Speed control sets the maximum fast speed, the Lo Speed sets the slower speed, and the Ramp Speed control determines how fast or slow the LFO speed ramps to those presets. With each step on the stomp switch, the LFO speed ramps to either the "faster" preset, or the "slower" preset. Once the LFO reaches the max preset, it remains at that speed until you step on the stomp switch again, then it ramps in the other direction towards the other preset.  

To simulate the extreme settings with a slow ramping, have your phaser set to a slower speed, and while you are playing cue a buddy to slowly turn up the speed control to a faster speed. And at some point cue him/her again to turn the speed control back down slowly. And repeat as random or as syncopated as you like. Just ask your helper to try an rotate the Speed control at the same rate. (There is a slight difference in how fast the ramp up and the ramp down actually occurs, but each are consistent)

With the actual LERA, if you set the Ramp Speed control to fast, then it's kinda like switching between two phasers, one set for a fast speed, and the other a slow speed.

Pretty cool the way R.G implemented the Ramp and Speed controls.

Anyway Shaggy, I have time tomorrow to help you get yours up and running. I'm in the States on Mountain Time Zone, should be able to reply to your posts quickly in the AM. If I think of a better troubleshooting path I'll post again when I get up.  

 

 

[Shaggy45]

ok check one looks good. check two i'm only getting  270k with the depth pot down and 370k with it up

[MAO]

That seems a bit low, with Depth up full, I'm getting around 800k on both my LERA version and standard nom nom.  

In-circuit resistance checks can be tricky to track down as there are other branches that could effect the readings. I can't spot an easy way to determine why your reading is so much lower without pulling parts off the board.

I don't want to send you on a wild goose chase, but I guess it's easy enough to pull the ICs and jfets and see if anything changes, assuming they are socketed. If the resistance goes higher, then replace the ICs and jfets 1 at a time until you spot a change. They may tell us something.  

Better yet, let's do the basic voltage checks.

Oh, and I assumed you were aware the Bias trimmer has the be set by ear to enable the phasing, usually just off the noon position. There is a small window of adjustment where the phasing will happen. You should be able to hear a phase shift while adjusting the Bias trimmer even if the phasing won't cycle automatically.

But that wouldn't explain that low resistance reading.

Here are my voltages with LERA switch OFF, DEPTH up full, SPEED at 75% up. Feedback switch OFF, Up/down switch UP, Hi Speed, Lo Speed and Ramp Speed up full. (If your Ramp Speed is wired like the layout, which is backwards, then turn it all the way down for now)  

Supply voltage 9.29v

From top IC to bottom IC

TL072
1 - 5.03
2 - 5.09
3 - 5.09
4 - 0
5 - 5.09
6 - 5.09
7 - 5.12
8 - 9.02

TL072
1 - 5.03
2 - 5.09
3 - 5.09
4 - 0
5 - 5.09
6 - 5.09
7 - 5.03
8 - 9.02

TL072
1 - 5.03
2 - 5.09
3 - 4.8
4 - 0
5 - 0
6 - 2.1
7 - 2.1
8 - 9.02

LM358
1 - 0
2 - 8.38 (up/down switch in the up position, will be lower in the down position)
3 - 4.27 (up/down switch in the up position, will be lower in the down position)
4 - 0
5 - varies
6 - varies
7 - varies
8 - 9.02

jfets  (I'm using 2sk246, your gate reading will probably be different for 2n5952, but should be varying)
D - 5.09
S - 5.09
G - varies (2.6-2.9)

2n5087
C - 3.55
B - 4.54
E - 5.09
 
2n5088 - not checked
2n5088 - not checked

[MAO]

posted my new verified layout (original layout probably ok too)

Also updated Ramp Speed connections on original layout. (they were reversed)

 

[Shaggy45]

Supply voltage 8.96v

From top IC to bottom IC

TL072
1 - 4.71
2 - 4.71
3 - 4.71
4 - 0
5 - 4.71
6 - 4.71
7 - 4.71
8 - 8.69

TL072
1 - 4.72
2 - 4.71
3 - 4.71
4 - 0
5 - 4.71
6 - 4.71
7 - 4.72
8 - 8.69

TL072
1 - 4.71
2 - 4.70
3 - 4.50
4 - 0
5 - 0
6 - 8.14
7 - 8.14
8 - 8.69

LM358
1 - 0
2 - 8.04 (up/down switch in the up position, will be lower in the down position)
3 - 4.03 (up/down switch in the up position, will be lower in the down position)
4 - 0
5 - varies
6 - 5.26
7 - 7.43
8 - 8.69

jfets  
D - 4.71
S - 4.71
G - 5.33

2n5087
C - 3.019
B - 4.15
E - 4.71
 
2n5088 1 (far left)
e 0
b 0
c 8.0

2n5088 2 9right)
c 8.69
b 8.69
e 8.12

hope that helps. pin 6 & 7 on the bottom tl072 looks rather high in comparison to yours

[Shaggy45]

Original layout is verified. i realized today what i did wrong. i used a 3.9 ohm resistor not a 3.9m. thanks for your help mao and for the awesome layout.

just a caution to other builders. don't build when your on midnight shift. your brain doesn't function right lol

[MAO]

Those errors can be tricky to find, nice job!