Did I fry my CEM3379?

So I put my CEM3379 IC into its socket backwards, realized the mistake and I can’t get any sound out of it now. Oddly, though, I WAS able to get, what appeared to be, a mix of a Spanish and AM talk radio station, coming out of my monitors when I touched the wires I send to the output volume fader. Anyone ever fried a CEM IC?

You don’t need a fried chip to hear your cabling pick up radio stations.

Probe pins IC4.1, IC2.17 for sound.

Try a AluminiumFoilHat™ to prevent Aliens sending mystrious Z-Rays directly to your Brain…

Honestly the CEM is a rather rugged Chip, same happened to me, reversed the Chip to correct Alignment and worked fine. So don’t Panic and follow pichenettes brilliant troubleshooting.

Probe for sound? Could you describe the procedure?

Connect the Ring of a 6,35mm Jack to GND on the Board and the Tip to a piece of Probing Wire, Plug that into your favorite Mixer/Amp/Soundcard and poke around with the Probing wire…

Ok. After engaging the test tone, I can hear it faintly at IC4 pin1, but nothing on IC2 , pin 17.

Hmm, seems something wrong between the connector and the TL072 (of which 1/2 is the Input Mixer), check the solder joints of IC4, R13, R14, R15, C15, J4 and make shure C15 is a bipolar type. IF this doesn’t work, try swapping the 072 by another one (theres one on your SSM, Dual SVF and IR3109 Filter board - or if you are as “normal” as me you have some on stock…) Try getting a nice audible signal at pin 1 of IC4, till then you can remove your precious CEM3379.

THE_BOOK™ is very helpful understanding what you did… thanks again and again and . . . . . !

Ok, roger that. Quick question. What does the “NP” near caps C1, C15 & C19 represent?

Non Polarized.

If they were “normal” polarized Electrolytic Caps only the half of the Audio Signal that swings around GND would get thru… so you put in Polarized (the ones with a white stripe at the negative Pole) in? If so, desolder, put in Nonpolarized and All is well that ends well™.

Next time i dont want a sissy “Roger That”, instead a “HUA” would be appreciated *rotfl

Dang it! I DID infact do that. Mouser doesn’t seem to have “audio-grade” (atleast in the description) bipolar aluminum electrolytic caps. But I hurried to an electronics store and found some bipolar/non-polar caps. NTE, but what the heck. A couple of questions HUA! There’s no indication of which lead I should solder to the + on the PCB. Non-polar/bi-polar caps, I’ve read, have terminals that switch from positive or negative depending on the circuit. So why the long and short lead? Why the “+” on the PCB? I checked the data sheet and it has no mention of which terminal is positive (although non-polar sounds like neither would be).

@CheeseNoOnions: I’ve been hitting mouser pretty hard the last few days, assembling the BOM for the DSP board. Here’s the “audio-grade” cap for c15. I’ve found a trick: when sourcing parts listed on mutable BOMs, try searching Mouser using the Digikey numbers Olivier gave! Works most of the time!

Hey thanks Bleo! I think I’ll order some of these and return the NTE caps I bought in a rush.

@ fcd72

Thanks for the info, it helped with an issue i was having as well.

yups, the silkscreening us a bit misleading as it uses the standard elko symbol, but its clearly labeled “NP”. NPs have the same set of legs as they run from the same production lines i assume…