defective logic level converter

[ERH]

I purchased the 8-channel Bi-directional Logic Level Converter to test SPI communication between an arduino and a 3.3v lcd (PiTFT). It was behaving erratically, so I checked with a voltmeter on a breadboard. It turns out it does not convert the voltage properly, for example I get around 1.5 volts when I should get 3.3. I think it is defective. (Tried two other converters in the same setting and they work fine). Is it possible to get a refund or replacement?

[Franklin97355]

Were they all the same purchase? Could you post a photo of your connections?

[ERH]

Thanks. I did not have my original set-up so I tried something similar. The set-up is simple, I give 3.3V to a low channel but get only 2.5V in the corresponding high channel. (I only have one 8 channel. I used a 4 channel for comparison. The breadboard power supply works fine, it gives clean 3.3 and 5 volts in the rails).

[adafruit_support_mike]

For the sake of completeness, would you do a couple passes of voltage measurement on the output pin and the VCCB pin please?

Breadboards are notorious for adding unexpected terms to a circuit (I once measured a 1.2v difference between rows connected by a jumper), so let's confirm 5v at VCCB while you're getting 2.5v at the output along that side.

[ERH]

Sure, thanks. I can do it tomorrow probably. I checked the power supply, but not on the pins. I was more worried about the cheap power supply than the breadboard (I am attaching their photos). By the way, my goal was to recreate your arduino tft shield from a pitft using their schematics (just to learn how they work, of course it is not worth the effort otherwise). It worked randomly a few times, then I realized logic level converter was behaving oddly. I really like the amount of documentation you provide for these tft shields.

[ERH]

I am attaching 3 measurements: 3.3V on LV pin, 5.0V on HV pin, 3.5V on a high channel. I sometimes get the correct 5.0V on some high channels.

[adafruit_support_mike]

Thank you.. that pretty much nails it down.

Send a note to [email protected] with a link to this thread and the folks there will get you a replacement. (#395)