Aion Electronics Lab Series L5 Build

[Rancher]

I'm just one day into populating two of the Aion Electronics Lab Series boards.  It appears D3 and D4, listed as 1N914s in the build doc, may be D4 and D5 on the board.  If this is true D3 would be a skipped part#.  Can anyone confirm?

[iggy76]

That's the way I see it too. The schematic shows D4 and D5 both as 1n4148 which I think are interchangeable with the 1n914 shown in the build doc.

Something else I've noticed:
Both the build doc and schematic shows C51 and C52 as 100uF, but the parts spreadsheet shows these as 220uf. Also the picture of the populated board on Aion's website looks to me like it used the larger 220uf.
I'm inclined to go with the schematics value, but I still consider myself a noob so I thought I'd ask.

[stonerbox]

I got a real L5 in my studio and I like it a lot for certain things. You wouldn't be able to do a video or just record the sound when they are done?

[iggy76]

Now I'm just confusing myself. Don't know where I got 220uF from.
Schematic and parts list show C53-C56 are 270uF.
C51 and C52 are 100uF. I guess I got confused because in the photo they look big for 100uF to me.

Still waiting for a few pots. If I can get this thing working I'll try to make a video report.

[Chewbakka]

Hi, I just build the L5 Preamp and it sounds great, but the popping sound when switching it on or off is horrendous.
Much worse than any of my other pedals.
Anybody else has these problems? Is this normal?
It is not the LED - I disconnected them and it still pops.
It even pops with the Master completely down.
Limiter on or off does not make a difference.
Disconnected D1 and D2 - still popping (what do D1 and D2 do anyway?)
Thank you if you can help

[yuka42]

Hi guys!  Did either of you get it built successfully?  Wondering if someone would be so kind as to compare voltages on two IC's.  Specifically IC11 and IC12.  The pedal sounds fantastic with an audio probe all the way up to after the Master pot.  Electronics are so cooool!  Love using an audio probe. haha!  Anyway....After that it sounds "garble-y" (....like a distorted vocoder or something haha).  Specifically, immediately after R76.  Also, the light for the compressor stays on, it gets brighter and reacts to signal when engaged, but when the comp switch is off it stays lit.  I tried to be extremely meticulous when installing parts and have since double checked the resistor values in the comp section.  I swapped the two CA3080's to see what would happen and the problem persists in the same spot.  I also had a RC4558 in IC12 and swapped it for a NE5532 that I had.  I double checked pot values, all good.  I used !n914's for D4 and D5.  All caps were ordered from mouser directly as indicated in the BOM.  I just noticed that Kevin has his MPSA13 (Q3) oriented upside down to what is indicated on my PCB.....(i've got mine flat side up)  Anyway, here's the IC values both with switch on and off.

I know it's a long shot but maybe someone smarter than me spots something.
Link to schematic...
https://aionelectronics.com/project/lab-series-l5-preamp/

IC11 CA3080 (switch on)

1: 0.000
2: 0.000
3: 0.000
4: -11.04V
5: -10.45V
6: -0.163V
7: +12.90V
8: 0.000

IC11 CA3080 (switch off)

1: 0.000
2: 0.000
3: 0.000
4: -12.03
5: -11.41
6: 0.100 (moving around a lot)
7: +12.91
8: 0.000

IC12 NE5532 (switch on)

1: -0.009
2: -0.001
3: -0.002
4: -11.04
5: 0.000
6: 0.000
7: 0.000
8: +12.89

IC12 NE5532 (switch off)

1: 0.013
2: 0.000
3: 0.000
4: -11.98
5: 0.000
6: 0.000
7: 0.012
8: +12.83


Thanks. 

Ryan.

[PRR]

C39 reversed polarity?

[yuka42]

Nope. It's installed correctly I think. I checked all the electro caps first thing. In doing so I noticed i did install C40 backwards.... so that was flipped back around.  I always forget about tantalums.  One day it'll sink in. But that's earlier in the circuit right after the multifilter.

Thanks very much for the response PRR. It does make sense.

Here's a gut shot. Hopefully the embedding works.

[yuka42]

Kevin says transistor is oriented the correct way. As per pcb.

More data: (compressor on)

-1.4v on cathode side of D4 and D5

Q1 (2n5457)

D: +14.93
S: +0.011
G: -0.139


Q2 (2n3906)

B: -0.647
C: -1.1 shifting
E: 0.000

Q3 (MPSA13)

B: -9.82
C: -6.32
E: -11.32

[EBK]

Immediately before R76 is good, and immediately after R76 is bad?
Any chance for a pic of the other side of the board?

[yuka42]

Immediately before R76 is good, and immediately after R76 is bad?
Any chance for a pic of the other side of the board?

Yes that's correct.  And on pin 2 of IC12 it sounds okay.  Pin 3 is garbled...like DC added sort of.  Side question....is leftover flux conductive?  Any tips on cleaning it?  Makes me nervous scraping it off so I just leave it mostly. 

I should clarify, i'm using my iPhone with clean, dynamic, music pumping at roughly 30mV AC for the audio probe.  I don't have a scope...yet.  Just using the old ears. 

Sorry about the massive picture in the last post.  Hopefully this will be better.

R76 is just southwest of the inside post of the top right pot.  Oriented straight down to the point below.

[EBK]

I suspect your problem lies around IC11.

[yuka42]

Thanks EBK.  I'll sniff around...

[EBK]

Thanks EBK.  I'll sniff around...

Try the easy stuff first: Remove and reinsert IC11.  If that doesn't change anything, replace IC11 if you have a spare.  If you do not have a spare, try swapping IC10 and IC11.

As a side note, do you have any kind of insulation on the back of that dual pot?

[yuka42]

I actually have swapped the two CA3080's with no change.  But I have a spare in a compressor pedal i can pop out and swap with just to be sure.  Should have bought an extra...

There's three layers of electrical tape on the back of that pot...best i could do in a pinch.  But I'll raise it slightly off the board when I test it next.  Just to be sure.

[digi2t]

I'm just one day into populating two of the Aion Electronics Lab Series boards.  It appears D3 and D4, listed as 1N914s in the build doc, may be D4 and D5 on the board.  If this is true D3 would be a skipped part#.  Can anyone confirm?

I think D3 is the limiter LED, you're right though, it's omitted. I used 1N4148's for D4 and D5. I ended up using OPA134's in IC1, IC2, and IC13 positions, and TL072 for the rest of the opamps.

Built it recently. It's great! Here's what mine looks like;

I got a real L5 in my studio and I like it a lot for certain things. You wouldn't be able to do a video or just record the sound when they are done?

Here you go...

As for the 2.7uF tantalum cap, you can parallel a 2.2uF with a 0.47uF. That's what I did (look closely at my picture, you'll see the two caps side by side). I got exactly 2.7uF on my cap meter with this combo.

[EBK]

I actually have swapped the two CA3080's with no change.  But I have a spare in a compressor pedal i can pop out and swap with just to be sure.  Should have bought an extra...

There's three layers of electrical tape on the back of that pot...best i could do in a pinch.  But I'll raise it slightly off the board when I test it next.  Just to be sure.

we can probably assume both chips are good... 
Your solder looks good. 
Your components appear to be good quality. 
Nothing is obviously backward (might consider that tantalum you had temporarily backwards though). 
Ive visually double checked about a dozen of your resistor and cap values (assuming they are what they say they are). 
Running out of easy stuff to try (which is likely why you are here anyway). 

Do you have a spare transistor you could swap in for Q1? 

I don't want to risk damaging anything, but if you remove IC11, is the signal good on both sides of R76?  (Shooting from the hip with that question.  To be more methodical, I would first have to figure out how the circuit is supposed to work.  )

Another check would be to verify all your transistor pinouts, assuming you know the manufacturers.  Sometimes they vary.

I'll stop for tonight because I don't think I'm actually saying anything useful. 

[yuka42]

Man, I so appreciate the comments. So here's the current situation...

I swapped ic11 with the one I had in the comp pedal. Still no good which I kinda figured. I looked at the mpsa13 values and they kinda gave  me a weird vibe. Hahaha. I looked up voltage drop and it seemed too much?  I honestly need to go to school for this stuff. Anyway, I swapped it with a spare I had and the garble disappeared!!  Woooo!  That'll teach me to socket transistors.  But....  comp circuit still is weird. I'll recalibrate it tomorrow. But the light remains on in either switch position and it doesn't seem to be dancing or making a dif on volume levels anymore. Maybe someone can comment on exactly how their comp circuit responds?  Is the level control a threshold?  Or input volume...

Here's the new darlington values. (Mpsa13)

C: -10.38. (Was -6.32)
B: -9.78
E: -11.04

Done for the night. Thanks again.

[digi2t]

The limiter control is counter-intuitive. Think of it as a sensitivity control, but backwards. It's most sensitive at 0, and least sensitive at 10. If you're going to use it, start at 10 and dial down until you get the desired limiter engagement. It also depends where you set your preamp volume as well. If your channel volume is at 0, and your limiter is at 10, and the LED is still lit, there's a problem.

[yuka42]

Excellent. Thanks for the explanation. That'll help out diagnosing...