Greetings to all, I have this tuner that does not stop automatic tuning (manual and direct works fine). I have replaced the IC LA1265 and some electrolytic capacitors in the circuit but the problem remained. I ask for help with similar defect and / or interpretation of the scheme.
I removed the front panel and the buttons all work, the automatic tuning in MW and LW works and the "TUNED" indicator comes on the display. In FM, the "TUNED" indicator never lights up, even with tuned stations manually and excellent playback. The stereo indication is also always off.
Check the power supplies to the tuner/memory ICs.
Possible small low voltage cap is used to retain storage, which may be linked to stereo indicator.
Don't mess with it unless you are sure what you are doing, parts are difficult to find sometimes.
Possible small low voltage cap is used to retain storage, which may be linked to stereo indicator.
Don't mess with it unless you are sure what you are doing, parts are difficult to find sometimes.
I don 't know your tuner model, but in general, among other things, it could be an FM demodulator tank that's slightly detuned or a crystal oscillator that is not exactly on frequency for some reason, causing a frequency offset that causes the tuner to indicate it's not tuned correctly.
Mind you, demodulator tanks are easy to damage when you try to trim them with the wrong tools.
Mind you, demodulator tanks are easy to damage when you try to trim them with the wrong tools.
See if there are any variable trimmer caps like this:
Note their precise adjustment position with a photo if you're going to twiddle them (and note they can be adjusted 180degrees out)
These (some brands of them at least) , on some products have a tendency to develop a flat spot (or even open circuit) - due to sitting it one position for decades.
This would upset any factory adjustment obviously in whichever circuit area they're in, so either replace one by one with new (after transferring its adjusted value to the new one).
I remember a few products losing a particular function and replacing the trimmer cap was the solution
Note their precise adjustment position with a photo if you're going to twiddle them (and note they can be adjusted 180degrees out)
These (some brands of them at least) , on some products have a tendency to develop a flat spot (or even open circuit) - due to sitting it one position for decades.
This would upset any factory adjustment obviously in whichever circuit area they're in, so either replace one by one with new (after transferring its adjusted value to the new one).
I remember a few products losing a particular function and replacing the trimmer cap was the solution
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Hi, I have the same problem with my T-85L, also how do you store wireless FM channels on this ?, anyone got an instruction manual for this?, can’t find one on the net that isn’t free.
Can you post a complete schematic or a link to the service manual. It may be a synthesizer problem. It would help if you could provide the service info. Thanks.
David.
David.
Agree with previous response. It's probably the FM detector, or as a previous response called it - the "demodulator tank". You need the service manual. Look for the "FM detector zero" adjustment step. The adjustment usually requires a DC voltmeter to monitor voltage at specified points, while adjusting a ferrite core in the detector coil. Use the proper nylon tool only to adjust the coil. A metal tool can crack it.