DBullock
New Member
Hi all ... interesting and useful thread. After regretting giving away my Sansui T-80 when I moved, I recently purchased another with a view of repairing it. The digital display is only partially working and no quartz lock. It has an F-3000 digital board and an F-3010 pre-scaler board. My investigation has concluded I have a faulty MSM5540..... The signal level works (IC04), but only a few of the 7 segment display segments work, one bar stuck on permanently. Others will sometimes work at half level whilst tuning. If I unplug the feed from the pre-scaler board I get no change when tuning AM/FM thus it looks like the Pre Scaler board is okay. I tried changing the 6Mhz crystal just in case and re-soldered many joints that looked okay. Having looked around it's difficult/expensive to buy a replacement MSM5540 IC, cheaper just to buy another tuner but I would like to restore this one. The options are trying to build a replacement 7 segment driver with new chips but even then I don't understand how the quartz locked circuit interfaces with this and can't find a MSM5540 data sheet. Can anyone offer any assistance?
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