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
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
Just tryed tuning all frequencies, i can save them but as usual it saves to 2 presets with same frequency, The exception is preset nº7 is allways at 108.5 no matter what you try to save there
Also when i save it must be allways to preset 2, 4 or 6 and then station 2 stores to 2 and 1, station 4 stores to 4 and 3 station 6 stores to 6 and 5.
Anyway when i power on starts with preset 2
Also when i save it must be allways to preset 2, 4 or 6 and then station 2 stores to 2 and 1, station 4 stores to 4 and 3 station 6 stores to 6 and 5.
Anyway when i power on starts with preset 2
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Random thought.
Remove the battery, manually discharge the points on the board the battery goes to. Check all rails are discharged.
Now place aluminium (tin foil) on the print around the uP that the battery backup supplies and ensure all pins are shorted. Press it hard onto the board to short everything out. This removes any residual charge that could be holding some logic in an incorrect state. Leave for an hour an two and then retest. Try it first without fitting the battery.
Remove the battery, manually discharge the points on the board the battery goes to. Check all rails are discharged.
Now place aluminium (tin foil) on the print around the uP that the battery backup supplies and ensure all pins are shorted. Press it hard onto the board to short everything out. This removes any residual charge that could be holding some logic in an incorrect state. Leave for an hour an two and then retest. Try it first without fitting the battery.
I, i´ve done as you said, without battery goes to tune at power on as it should, with battery back on it behaves as before, any more thoughts you can think of?
T.I.A
As I've typed this I'm going to post it
but I've spotted something else I think...... will add another post.That sounds strange...
The 5 volt rail supplies the uP via D22, the battery charges via R12 and when the rails collapse the uP is fed via the battery and D21 with D22 blocking current flowing back to the rest of the set.
Without being there and seeing what is happening I would first of all test the battery under load. It should support a 470 ohm resistor and the voltage hold up above 4 volts. Worth just seeing its OK because weird things can happen if they go very high resistance internally.
The two diodes... worth swapping for 1N4148's just to eliminate them.
There's nothing else around there beyond that.
The only weird thing to suggest would be to repeat the process of shorting the uP with foil but this time leave it overnight. Also heat the area around the uP with a hairdryer to heat the chip. Get it hot... why... because I have encountered chips that remain locked up in a weird state for a long time.
What's bugging me is the way battery is configured. I've pulled a different manual that shows it all as one (I wasn't using yours so don't know which version you posted) and the battery goes to the output of that Quad opamp and not ground. Not sure how all that comes together. Whatever is on pin 3 of the opamp should appear on pins 1 and 2.
C11 and C12???
Can't just immediately figure that out. Why connect the battery to that point.
C11 and C12???
Can't just immediately figure that out. Why connect the battery to that point.
Just going back to the battery and you measuring 5.2 volts the next day after switching it off. I wonder if that is to high. Sometimes a failing NiCad battery can allow the voltage to rise higher than it should across the battery but the battery is 'dead' and has no real capacity. I wonder if something like that is causing an issue with the chip.
Might be worth putting a meter across the battery when charging to see what you measure. Also try the discharge test I mentioned with a 470 ohm (or something around that value).
Might be worth putting a meter across the battery when charging to see what you measure. Also try the discharge test I mentioned with a 470 ohm (or something around that value).