Teensy Audio shield failed after two days

[cjames53]

I'm putting together a project that involves a half-dozen Teensy 4.1 + Audio shield systems. One of the audio shields died after just two days -- the SD reader won't initialize any more. I verified that the micro-SD chip is OK, and I replaced the Audio shield with another (they're paired to the Teensy 4.1 with headers) and the replacement works fine.

Several people complained in another forum (sorry, can't find it again) that they received dead Audio shields, or that the Audio Shields died right away. One guy reported that three of the four he ordered were dead on arrival. Is there a known quality problem with the Audio Shields? Do I need to order extras to have on hand for this project? I love the product, but I need these to work reliably.

Thanks,
Craig

 

[clinker8]

It is customary here to include schematics, code, and pictures to help us help you. It is possible that the boards were mishandled, or defective. Were the parts ordered from PJRC directly, or one of its distributors, or from a different supplier? However, its also true that issues could arise from your set up, wiring or code. If you would be so kind, please attach more information, as indicated.

 

[KenHahn]

I don't think you need to be concerned about an inherent quality issue with the product.

I install the audio adapter into a system I sell and each gets tested as part of that system. I also have a couple of bench test units that get used and abused regularly with SD cards frequently being removed and reinserted. I have never seen a bad one out of the hundred or so I have tested nor has one of my test units gone bad on me.

If someone received 3 out of 4 bad units, something else was definitely going on.

As to your specific problem, if you haven't already, you might double check the soldering of the pins on the SD adapter to make sure there isn't perhaps a cold solder joint.

 

[cjames53]

It is customary here to include schematics, code, and pictures to help us help you. It is possible that the boards were mishandled, or defective. Were the parts ordered from PJRC directly, or one of its distributors, or from a different supplier? However, its also true that issues could arise from your set up, wiring or code. If you would be so kind, please attach more information, as indicated.

Thanks, I'll answer your questions, but first more information. I have since found (trial-and-error) that sometimes reinserting the SD chip fixes the problem -- twice out of a dozen attempts. So my suspicion is that this is a mechanical problem: the SD card reader's contacts are defective in some way. The SD card works in other Audio shields and in a computer.

To answer your questions:

I purchase the parts directly from PJRC. It's unlikely they were mishandled; I'm an EE with extensive experience assembling circuitry. I double-checked the soldering; a visual inspection looks good, and a continuity check with an ohm-meter shows that all pins on the header are soldered correctly.

Regarding wiring, the Audio shield is attached directly to the Teensy 4.1 with male/female header pins (see photo).

The code used is PJRC's own Arduino example: File-->Examples-->SD-->listfiles (where "SD" is in the "Examples for Teensy 4.1" menu section). When run, it reports:

Initializing SD card...initialization failed!

As I mentioned, I have several other Teensy 4.1 boards and Audio shields. The failed Audio board fails on any Teensy 4.1, and the other Audio shields work on every Teensy 4.1, so it's clearly just this one unit.

 

[clinker8]

Also an EE, although retired. Have to ask those sorts of questions, because, well, it's tough to get a sense of people's experience, from first posts.

On your visual inspection, is this by eye, or under magnification? I've found all sorts of blobs and splashes of solder under magnification that escapes a quick look. I have a stereo microscope for circuit inspection, which easily shows solder balls and similar sized issues or cracks. How are the solder joints on the Audio card, in particular the SD card socket. Perhaps there is a micro crack there. You need at least 15-20X magnification to see stuff like that. If you don't have that level of magnification, perhaps a simple reflow of the SD card solder joints might help. At least the contacts are out near the edge, where it would be easy to touch up, either with a micro tip iron, or even hot air.

As an aside, how do you like those wire to board connectors? Do they work well?

Out of curiosity, why are you not using the SD card on the Teensy itself?

 

[cjames53]

Also an EE, although retired. Have to ask those sorts of questions, because, well, it's tough to get a sense of people's experience, from first posts.

Indeed, and I appreciate the questions.

I have a stereo microscope for circuit inspection...

Good idea, I'll double check, and re-flowing the soldering certainly won't hurt and might work.

As an aside, how do you like those wire to board connectors? Do they work well?

They work quite well; there's a knife connector inside that grips the wire reliably. They're a little time-consuming to assemble -- each block of connecters is assembled from single connectors that snap together. If you need a different number of contacts than what they ship, you have to use an xacto knife to carefully pry the end-cap off, pry apart the switches, and reassemble into the size you want. In my case, I bought several blocks of five, and had to remove one contact from each. It's tedious when you have to do a bunch of them.

Another problem is that they have two pins per contact. If you look at the photo, you can see that the left-most two connectors are for supplying power and ground to an external device (an Adafruit Gemma-M0). Because of the second pin on each connector, each connector joins the power or ground to the breadboard's pins directly behind it, which means that whole end of the board can't be used for anything else.

I may change to a screw-connector that Adafruit sells, which only has a single pin per terminal, so I could solder it directly to the +3.3V and GND conductors.

Out of curiosity, why are you not using the SD card on the Teensy itself?

We wanted (and plan) to use the Teensy 4.0, but they weren't available due to chip shortages. We're substituting the Teensy 4.1, and just want to keep the software the same. (I'm working with artists, very non-technical.) I suppose for the defective Audio shield, I could change the pin definitions in the software to use the SD on the Teensy 4.1 and use the device myself for testing.

Cheers,
Craig