HELP - 3080 IC Problems With Compressor

[Svebster]

Hi,

So I have a problem that I never even thought could be a problem. I've built 2 Ross compressor pedals using FuzzDog PCBs. The pedal, as common for a compressor, uses 1 CA3080 chip. I also have an analogman compressor thats based on the same circuit which also uses a 3080 chip. When I tested the 2 pedals one didn't work and I found out that the IC was the reason because I swapped out the ICs and both pedals worked, so one of the 3080s was faulty. At least thats what I thought. So I had 2 working ICs in total, one from one of the builds that worked and I even took out the one from the analogman pedal. I tried both IC's in all 3 pedals so I ordered some new 3080s as I was still missing one. I just received the ICs and none of them work... The sound out of the compressor is gated and distorted - No sound until I dig in more, but the sound is distorted then.

Is there a difference in 3080 ICs?? I've never seen anyone specify the chip. Are the batch numbers important?? Does anyone know a solution for this / had the same problem?? Does anyone know the circuit and knows if there are any components that bias the chip or so?? I have no Idea what to do as the circuit and everything is fine as it works with some of the IC's.

All the IC's are intersil including the one out of the analogman pedal. Just the numbers below the CA3080E description differ. I took a photo of one below:

[duck_arse]

svebster - you've linked an "html" page as an image. you need to get the image address from imgur, paste that instead. it should look quite like this (no s in http, just to be sure) ....

Code Select Expand

http://i.imgur.com/roaHLp7.jpg

as to your 3080's, buying them "from the interwebs" seems a worse and worse idea, from the number of people having problems with them. from one of the big parts houses, or one of the pedal parts suppliers, you should be safe.

and we want your voltages, same for any debug. the IC pin voltages and the transistor pins, please. there is a debug thread sticky somewhere .....

[Svebster]

Ok, I measured the pins on the IC. My multimeter is not super accurate but here they are:

1 1v
2 1.2v
3 1.2v
4 9v
5 8v
6 7v
7 0v
8 0.8v

I ordered 2 chips from ebay that don't work and one from Banzai music which also doesn't work (which was a lot more expensive).

[R.G.]

Ok, I measured the pins on the IC. My multimeter is not super accurate but here they are:

1 1v
2 1.2v
3 1.2v
4 9v
5 8v
6 7v
7 0v
8 0.8v

I sincerely hope that your pin numbering is incorrect. If it's not, there's a good chance that the IC is dead.
Looking up "3080 IC", the first few results I get are datasheets. Pins 1 and 8 are not connected on this variant of the chip. Pin 4 is the most negative power supply voltage, pin 7 is the most positive powe5r supply voltage, and pin 5 is the amplifier bias pin.   If your numbering is correct, pin 4 is 9V more positive than pin 7, and all of the internal connections on the IC are probably fused.  Once you get the power supply right, pin 5 should never be higher than about 0.5-0.6V compared to pin 4. If it's higher than pin 4 by more than that, the chip is probably dead.

[Svebster]

Thanks for your answer, my pinout is correct. I just put in the working analogman IC and measured again:

1 0v
2 0.9v
3 0.9v
4 9v
5 8v
6 2.8v
7 0v
8 0v

Very different!

The chip is also made by intersil and looks exactly the same, only the number beneath the CA3080E description is different.

So does that mean most ca3080 chips you can buy are broken? Because thats the case for me then. Ibought them from 2 different shops and they were all faulty apart from 1. 1/4 was working??

Does anyone know a source for 3080 chips in the UK that delivers working chips?

Thnaks

[Ice-9]

Not trying to sound cheeky, but are you sure you are numbering he IC pins in the correct order. ie pin 1,2,3,4 quite obvious pin 5 is then directly opposite pin 4 and pin 8 is opposite pin 1. I have seen many people count pins 5 to 8 in the wrong direction.

The 3080 is also widely sold on the internet with out of spec parts and the likelihood of getting good ones is getting to be a gamble.

[anotherjim]

If you are reading the IC pins correct, then maybe you have the 9v power supply polarity reversed? That pcb has no reverse polarity protection, in fact +9v and 0v wires go right to the CA3080 supply pins - so nothing to protect it from being toasted. Yes, IC's can be fried without letting any magic smoke out.

...so, for the chips sake, I hope you are reading the pin out wrong.
Note, that it very wise to check power supply voltages on the chips at their socket pins BEFORE fitting the chip. That's one main reason for fitting sockets in the first place.

[bluebunny]

Note, that it very wise to check power supply voltages on the chips at their socket pins BEFORE fitting the chip.

^^ This.

Bears repeating, many times over.

[rankot]

You can try to replace it with LM13700, I suppose there's even conversion board for that.

[rankot]

And it's actually here: http://tagboardeffects.blogspot.rs/2012/10/emma-transmorgrifier.html

[duck_arse]

[I think the Svebster board has pads for either 13700/or 3080.]

[PRR]

The '3080 OTA was out of production a long time.

Back-alley scammers re-inked other chips and flooded the market.

A Known-Good source is Small Bear Electronics. Or Rochester. The Bear worked with Rochester to get the '3080 put back in small production. (Bear's price is better.)

I'm confused that you show large voltage on pin 5 and "working". Pin 5 is, as R.G. says, two small diodes to V- and CAN'T go over 1.2V without destruction. However a high p5 voltage is typical on many of the re-marked scam chips.

[thermionix]

When did Intersil quit making 3080s?  The chip in OP's picture appears to have a date code of late 2015.

Comparing the Intersil logo to that of a known real one, it's very close but not exactly the same.  Some fakes I've seen here have worse looking logos.  But that one in the picture I'm on the fence about, could be just a printing variation.

---------

I checked Google Images to try to find some pictures to illustrate what I'm talking about, but most I see look worse than OP's.  Probably no coincidence that they are almost all from Ebay and AliExpress.  Such as these:



I'm not claiming any expertise.  But I've seen fakes in some threads here with logos like those.  The one I have has much sharper printing, and the "underline" is more like OP's.

[PRR]

> When did Intersil quit making 3080s?

http://www.till.com/blog/archives/2005/06/last_of_the_ota.html

[lars-musik]

I tried all kinds of sources for that chip - and most didn't work. None of the ebay buys at least.

Have you seen, that they are in production again in an SO-8 package? I have ordered some but not yet tested.

For example here:

https://www.musikding.de/CA3080AM-SMD

[Svebster]

Yeah, I talked to my eBay seller and he actually had more complaints about non working chips in his last batch. I already ordered a tested 3080 chip made by RCA. I hope this is gonna work! I'm sure my board works and everything is connected correctly as the pedal works with some chips!

Thanks!

[Svebster]

The IC arrived and the pedal works. - Good place in the UK to buy the chip: www.littlediode.com

[snk]

+1 for buying CA3080 from reliable sellers : I just got my first experience of a fake/dodgy chip, and cheap prices aren't worth the time wasted for debugging.
I used the daughterboard adapter on veroboard that Rankot mentionned above, and now my Transmorgrifier clone works using a LM13700.
The adapter is not very elegant on the circuit, but who cares