Relays still not switching

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af7ux
 

Posts: 15
Joined: 17 May 2022, 18:52

Relays still not switching

Post by af7ux »

Hello, some time back, I broke my radio quite badly by shorting the 12v to speaker +. Ultimately I broke the mainboard. See viewtopic.php?t=461 for details.

Well, I have a new mainboard, it works, it switches the relays on the otherwise unbuilt new RF board. On the old RF board, the relays do not switch. I replaced the tca9555 with a pca9555 since we suspected that might have gotten fried. I have verified that I have +5v to the chip, but the relays still will not switch. I can switch them with a 5v supply, so the relays do work.

I checked a few points with my scope, and I do see signals on sda, but no pulse to the relays, whereas I do see the pulse on the working board.

What else could be broken on the RF board to cause this? Did I manage to replace a bad chip with another bad chip?
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