Aion Aurora Compressor CA3080 Issue

[cnspedalbuilder]

Hello, I'm building the Aion Aurora Compressor--it's an MXR DynaComp/Ross clone with some mods
https://www.dropbox.com/s/d7m5f9rbe6d68f2/aion-aurora-ross-compressor-documentation.pdf?dl=1

I don't want to waste anyone's time, so I'll get right to it: When pedal is activated, no sound. Pedal works in bypass mode. I've ruled out issues related to offboard wiring, and run through w/audioprobe and DMM.

I get sound all the way to IC pin 3 (op amp input) but no sound from IC pin 6 (output). IC is socketed, but continuity tests ruled out a problem w/soldering of socket. Here are the IC Voltages: (I'm leaving out 1 and 8 because these are not connected in the circuit)
Pin 2: 4.88
3: 4.86
4: 0 (ground)
5: 6.64
6: 2.675
7:9.48

Inspection of posts on the Ross http://www.generalguitargadgets.com/pdf/ggg_dnr_ross_instruct.pdf indicates that my voltages for Pin 5 are way too high and pin 6 is too low.

Is the IC bad, or is it possible that the circuitry from pin 5 to the sustain pot could be missing things up? Thank you as always foryour help!

[PRR]

Where did you get the '3080?

After following many '3080 project de-bugs, I think that *MOST* '3080s on the market are FAKE.

The seller must not only be honest and diligent, but also have customers who build with '3080 and will alert quickly if they get duds.

We know that Small Bear has good '3080s.

I know one major Euro webshop shipped duds a year or two ago.

[cnspedalbuilder]

@PRR yes I should've clarified this: I got the CA3080AE IC from Smallbear. I would've just assumed the IC is bad, but I figured that SmallBear would have good QC.

It seems to me though that either this IC is bad or I've somehow messed up the parts of the circuit that link with Pin 5. Any way to know for sure, other than buying a new IC?

[aion]

It seems to me though that either this IC is bad or I've somehow messed up the parts of the circuit that link with Pin 5. Any way to know for sure, other than buying a new IC?

Nope That would be my best guess as well. I've had identical issues more than once (signal stops at the IC) and each time it was fixed by replacing the CA3080. If you do order a 2nd 3080 and it works, then SBE would probably refund you the cost on the first one. SBE's are new production, and very reliable, but a 3080 still isn't the hardiest chip in the world, so it's not inconceivable that one of the new ones could be bad here and there.

[PRR]

OK. But pin 5 at 6V is just impossible. Unlike most chip pins, '3080 pin 5 has *NO* over-current protection (what aion said). Stray current from a mis-connection, or even static electricity, can blow the guts at pin 5. I'd be wary of "continuity checks" at pin 5. Most DMMs will be safe but I'm never sure. As you don't report a wiring error, and if you are in/near the US then you sure can't have static discharge in this humidity, it is a mystery.

Point "Small Bear" Steve at this thread. He may have a better thought.

[smallbearelec]

Hi Paul--

We are sending another chip. These Are re-makes rather than old-stock Intersil, so I figure it's just possible that the customer got a dud.

[Tony Forestiere]

Hi Paul--

We are sending another chip. These Are re-makes rather than old-stock Intersil, so I figure it's just possible that the customer got a dud.

A doff of the cap to a true gentleman of his word.

[cnspedalbuilder]

@Steve, you rock, thank you.

@Paul:

I'd be wary of "continuity checks" at pin 5. Most DMMs will be safe but I'm never sure. As you don't report a wiring error, and if you are in/near the US then you sure can't have static discharge in this humidity, it is a mystery.

Let me make sure I understand: are you thinking that the 3080 might have died due to a problem elsewhere in the circuit, static, or a short during continuity checks? Re: static, I'm in California, but does that matter?

pin 5 at 6V is just impossible.

I guess it's possible that I made a mistake in the measurement. Do you really mean the value could not be possible, or that it's not in the reasonable range for a working circuit?

BTW, I should add that I am doing this from an Aion PCB so wiring isn't a problem.

[LightSoundGeometry]

any results on the GFX 3080/LM3700 daughter board?



https://www.google.com/search?q=lm3700+daughter+board+guitar+fx&biw=1360&bih=604&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjx1Zqc_8bOAhUIRSYKHbI_C6QQ_AUIBygC#tbm=isch&q=lm3700+daughterboard+guitar+fx&imgrc=3Csx6-ulhKiDzM%3A

I have 2 of those lm3700 laying around, a good compressor would be a good use for them!

[287m]

any results on the GFX 3080/LM3700 daughter board?



https://www.google.com/search?q=lm3700+daughter+board+guitar+fx&biw=1360&bih=604&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjx1Zqc_8bOAhUIRSYKHbI_C6QQ_AUIBygC#tbm=isch&q=lm3700+daughterboard+guitar+fx&imgrc=3Csx6-ulhKiDzM%3A

I have 2 of those lm3700 laying around, a good compressor would be a good use for them!

i think better use storyboardist http://effectslayouts.blogspot.co.id/2015/11/lm13700-to-ca3080-conversion-board.html

[PRR]

Pin 5 is a diode (or two) to ground. A diode can't show over 0.8V (or 1.6V) unless the current is so high the diode "blows". After that, it can go to "any" voltage, but it isn't any good any more.

At this point we will never know(*) what happened. Maybe static damage, accidental contact to a bad voltage, or it may have been bad from the start (whether Intersil or new-made).

(*) Actually, some very nasty solvent and a stereomicroscope, someone could examine the naked chip inside and see if it looks like bad fabrication or something got melted.

[cnspedalbuilder]

OK, I had hoped that I would not need to revive this thread but here's an update:
Steve sent me a new CA3080 (thank you!). The pedal still does not work. After working on vero this PCB should have been easy The most likely scenario is that the CA3080 is/was fine, the PCB is fine, and I was somehow careless or made a bad substitution. Any ideas from the DIY team?

As a refresher,
1. Pedal is the Aion Aurora Ross/MXR/JangleBox compressor https://aionelectronics.com/project/aurora-ross-dyna-compressor/
Build docs are here: https://www.dropbox.com/s/d7m5f9rbe6d68f2/aion-aurora-ross-compressor-documentation.pdf?dl=1

2. Bypass is fine, but no sound comes when pedal is on.

3. If I touch a jumper on pins 2 or 3 on the OpAmp (CA3080 IC) with other side on the PCB output solder pad, I get the clean sound. So, it's not a switch issue, and that means at least the signal path is making it to the 3080.

4. Here are my current voltages:
IC (pins 2-7): 4.91, 4.91, 0, 8.64, 2.67, 9.49 [yes PRR, unfortunately, pin 5 is at an impossible value again!]

Q1: 7.7, 2.2, 1.81
Q2: 7.38, 2.68, 2.09
Q3: 0, 2, 9.4
Q4: 0, .6mV? [DMM kept flitting around a few millivolts], 9.44
Q5: 9.49, 9.43, 9

Please note that the transistor labels for the Aion DO NOT match the Ross/MXR schematics.

I can add pictures, but not very helpful because many joints are obscured by the on board pots.

So far, continuity and resistor values match, except that R11 is 220K not 150 K. Also, I am not sure if C13 is working right, but I can't be sure because it's obscured by the pot and removing the pot from the double sided PCB is extremely difficult.

Any ideas are greatly appreciated. Cheers.

[PRR]

IC socket?

Are you measuring pin 5 at the PCB, at an upstream pot, or at the actual chip pin?

Be VERY careful. A slip that shorts pin 5 to almost any other pin may blow pin 5 (and the chip).

[cnspedalbuilder]

Paul, good question. I am definitely socketing the IC. For some dumb reason I only socketed 3 of the five transistors.

I have measured pin 5 typically from the chip pin because it's easy. I have done it from an upstream pot and PCB and numbers are same. The one sketchy thing is that I sometimes have trouble getting the reading from bottom of PCB. I re-did that solder joint yesterday, but still no luck I suppose it's possible it's already too late if the new CA3080 is down.

Would you say that it's pretty certain that the problem is related to the part of the circuit emerging from Pin 5? I guess pin 5 receives current that is used to bias op amp?

[PRR]

I' grasping at straws and hoping someone else will have an idea.

Gently remove the '3080. Put a 1K resistor pin 5 to pin 4. Power up, and see what voltage is on pin 5.

[cnspedalbuilder]

PRR good idea! I ran out of 1ks   but will try this as son as I can. in the meantime, would a 2k work?

[duck_arse]

have we seen any photos of your built board? is it possible that the sockets aren't contacting the IC's pins? perhaps jamb a cut-off resistor leg in between the socket contact and the IC leg, see if that works (it has for others).

[cnspedalbuilder]

Thanks Stephen, continuity checks went fine for all the pins, but it would not hurt to stuff the IC socket and check.

Also, no I didn't show photos of the board because the on-board pots make a lot of the joints hard to see...and also because the flux stains look awful on a white board

I will do the test and get photos if that would help. Is it fair to say that the problem can be traced to pin 5?

[PRR]

What do you get with 2K?

> pots make a lot of the joints hard to see

In my hard-earned experience, if you can't inspect it, you can't debug it.

I've gotten away from miniature electronics. In house-power and tractor wiring I spend as much thought on making all connections easily-seen as I do on the function.

[cnspedalbuilder]

What do you get with 2K?

188 mV

have we seen any photos of your built board? is it possible that the sockets aren't contacting the IC's pins? perhaps jamb a cut-off resistor leg in between the socket contact and the IC leg, see if that works (it has for others).

I will post photos asap. There's no gap in the IC socket to squeeze in a pin. Are you thinking of putting a very small pin in the empty socket and then adding the IC?