QUAD FM4 always go to prest 2 at power on

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#41
So perhaps yours is a later version in the scheme of things.

I found this:

Screenshot 2023-05-18 181139.png
 
#45
Hmmm. I thought it worked OK tbh without the battery 🙂 from the earlier post or has the fault changed a little:

without battery goes to tune at power on as it should, with battery back on it behaves as before
Click to expand...

So... I think you have to try a chip to prove it one way or the other.
 
#46

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#48
Could we be looking at this all wrong?

Without actually having it front of me its hard to decipher what is happening. The title reads:

QUAD FM4 always go to prest 2 at power on​

Click to expand...

That's pretty specific.

First post reads:

I recently purchased a quad fm4 tuner serial 24996, i can manualy tune any station but when i try to save i can do it at preset 2 and it saves it to 1 and 2 with same frequency, then if i try to save a diferent frequency in preset 1 it saves and changes the number 2 as well to same, when switched off no matter what station allways start at number 2 preset.
when i press the preset buttons from 2 to 1 it goes, but not from 1 to 2, i need to press 5 and then i can press 2, if someone had such issue or have possible slution i will apreciate
T:I:A
Click to expand...

Could it be something as simple as a problem with the keyscan to the uP? Something like a leaky diode (DI-D4) or a leaky switch or conductive goo on the switches?

Might be worth desoldering the four diodes D1- D4 and also pins 2 and 3 of the uP and seeing how it behaves.

Screenshot 2023-05-19 061900.png
 
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