Teensy Amazon Products

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TonyAme

Active member
Hello,

Thank you for reading. I bought a Teensy 4.0 and Audio Board Rev. D from Amazon and been having problems with my custom PCB audio circuit, whereas previously I did not. I noticed that on the Teensy 4.0 purchased from Amazon it had "NXP" printed on the chip, where the previous Teensy 4.0 chips did not.

*When I use a 9V power adapter rated at 1 Amp the 7805 regulator on my custom pcb over heats and the Teensy does not function.
The 7805 Regulator only heats up when I plug in the Teensy 4.0 + Audio board Rev D. When Powering the custom PCB (seen below) without the Teensy + Audio Board = No heating of 7805.

My custom PCB that holds the Teensy 4.0 and the Audio Board Rev D;
TeensySynthI2C.png

CustomPCB_Teensy_AudioBoard.jpg
 
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Ok, when using the Teensy with an Audio Board like that, it has happened that parts from the underside of the Teensy touch parts of the Audio Board and SHORT OUT. That's one of the reasons why it's better to use tall plug and sockets for the Sound/Audio board to/from the Teensy.
 
BriComp said:
Ok, when using the Teensy with an Audio Board like that, it has happened that parts from the underside of the Teensy touch parts of the Audio Board and SHORT OUT. That's one of the reasons why it's better to use tall plug and sockets for the Sound/Audio board to/from the Teensy.
Click to expand...
Thank you. I did use the tall headers on the first board that I put together and has the same problem. I will investigate this possibility.

Edit: Ok, when carefully inspecting the two boards nothing is contacting in a short, all separated. Originally I used the Rev D2 audio board (which was used on the functional/working version of my circuit, the one in question uses the Rev D.
 
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Yes, AGND and GND can be connected.
VGND (ground terminal of the headphone jack) and either GND or AGND must not be connected.

When you install both T4.0+AudioBoard on your board, does the Teensy work fine for some time until the voltage regulator overheats?

Measuring the current would tell more what is happening. You could use the power switch pads (with the switch set to OFF) and a multimeter set to measure DC current, range 2A will be safer for the first test.
CustomPCB_Teensy_AudioBoard.jpg

If it shows more than 150 mA then something is not right. Try testing different scenarios:
- Teensy only, no audio board
- Audio board only, no Teensy

If the current is in 100-150mA range and the answer to the question above is yes (Teensy works for some time) this is probably a voltage regulator's thermal issue. A small heatsink should do the job, although mounting it to a TO220 package without any mechanical support, relying on the soldered chip terminals only is risky.
 
Pio said:
Yes, AGND and GND can be connected.
VGND (ground terminal of the headphone jack) and either GND or AGND must not be connected.

When you install both T4.0+AudioBoard on your board, does the Teensy work fine for some time until the voltage regulator overheats?

Measuring the current would tell more what is happening. You could use the power switch pads (with the switch set to OFF) and a multimeter set to measure DC current, range 2A will be safer for the first test.
View attachment 38719

If it shows more than 150 mA then something is not right. Try testing different scenarios:
- Teensy only, no audio board
- Audio board only, no Teensy

If the current is in 100-150mA range and the answer to the question above is yes (Teensy works for some time) this is probably a voltage regulator's thermal issue. A small heatsink should do the job, although mounting it to a TO220 package without any mechanical support, relying on the soldered chip terminals only is risky.
Click to expand...
Thanks very much for the great help on this, very much appreciated.
TonyAm
 
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