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ONKYO T-4700 Tuner Preset Memory Loss Repair

M

mbraun1973

New Member
I could not find any useful info here for this particular tuner model, so here's how to fix the issue:

The T-4700 tuner's preset memory and antenna selector is backed up via 0.1F 5.5V Super Capacitor (Capacitor C707 on the front display and button panel board). The problem is that the capacitor is located hidden under the LCD display!! Instead of de-soldering everything from the LCD display, an alternative is to de-solder only the small flat supercap. This can be done by just slightly separating the upper part of the LCD display from the board since all soldered connections are at the bottom and the LED lights to the left. This will provide just enough room to wiggle the bad supercap out after de-soldering it and perhaps trimming its connections with a tiny wire cutter for easier removal.

The new supercap can be added from the rear of the board (where it should have been installed to begin with!)

Have fun!
 
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Wow! Should I just print out your instructions and hand it over to a tech? This seems more than I'm willing to do. Silly design. My fisher digital tuner fm-2421 from 1980 still works well and holds the stations.
 
mbraun1973. Welcome to AK. Nice fix. Just makes sure of the polarity of the cap putting the new one in.
 
Dear mbraun1973. Thanks a lot for this perfect instructions! The memory loss of my T-4700 unnerved me for years now. In other forums I read that the caps of the T-4700 tend to dry out which leads to the memory loss, without being specific which one. So I replaced all big caps on the main board which could be involved in energy storage to maintain the memory, without success. I never dreamt of looking between the display and the board!
 
Same with the T-4500. Same location, PITA to remove, definately trim off the ends to facilitate removal. Regardless, had to separate display from board by 1/8" to remove. Tested after removal and display is fine. Now for the new supercap, needless to say will install on accessable side of board this time.
 
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