Hmmm. I thought it worked OK tbh without the battery
from the earlier post or has the fault changed a little:
So... I think you have to try a chip to prove it one way or the other.
without battery goes to tune at power on as it should, with battery back on it behaves as before
So... I think you have to try a chip to prove it one way or the other.
Have you tried the FM4 service manual diagnosis chart?
The Sevice manual is in the public domain, and look at page 9 for a chart of differential daignosis
https://www.dadaelectronics.eu/uploads/downloads/02_Quad-Service-Manuals/Quad-FM4-Service-Manual.pdf
I think the problem lies in this group (extract from chart below), and what follows in the manual are pages of the fine details on assessment and fix.
ATB!
The Sevice manual is in the public domain, and look at page 9 for a chart of differential daignosis
https://www.dadaelectronics.eu/uploads/downloads/02_Quad-Service-Manuals/Quad-FM4-Service-Manual.pdf
I think the problem lies in this group (extract from chart below), and what follows in the manual are pages of the fine details on assessment and fix.
ATB!
Attachments
Voltage across each of the other three input pairs should be zero. Not sure what this pair should do, it's not connected output to inverting input like the others.pins 12-13 760mV
D23 should definitely be lit if it's an LED. Replace it if not.
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:
That's pretty specific.
First post reads:
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.
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
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
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.
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