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Yamaha TX-400U Tuner Station Memory not storing programs.

H/K crazy

H/K crazy

Active Member
I have a TX-400U Natural Sound tuner that no longer holds the programmed stations in . When powered up, it does not play the last station listened to when it was last powered up. Most of the time it displays 1010 AM, a station that has not even been programed into it's program memory. I figure that it must be a capacitor since I don't see any battery. Does anyone here know which cap works to hold the program memory ?
 
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Yamaha TX-400 Stereo Tuner Manual | HiFi Engine
SM shows the cap, C143 at front of the circuit board on the same end as the antenna connections. But it seems to be a larger cap and isolated so you should see it easily.

Post a pic of the guts as I didn't see one on the web. Be nice to have a pic of the board with that memory cap in the shot.
 
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Thanks for the answers, in the meantime I found out that as you say, Blue Shadow, it is cap C143 which the service manual parts list says is a .047F 5.5V super capacitor. Thanks to everyone who took the time to answer.
 
H/K crazy said:
Thanks for the answers, in the meantime I found out that as you say, Blue Shadow, it is cap C143 which the service manual parts list says is a .047F 5.5V super capacitor. Thanks to everyone who took the time to answer.
Click to expand...

You could even replace that with a bigger value cap for longer memory retention time, as long as it’s the same voltage as 5.5V. I have an old Technics tuner with 1.1F and 5.3V, actually they are three super caps of 3.3F of 1.8V each in series. Just keep the total equivalent voltage at 5.5V, because that drives the memory chip.
 
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