Currently, I am prototyping a word clock that uses 2 JQ6500 sound modules (the ones without SD card slot).
Maybe somone could help me with the issue as follows:
The first JQ6500 module generates the chiming sounds every quarter / at full hour.
The second JQ6500 is bound to play the tick-tock sound.
Therefore, I have sampled a mp3-file that covers one “tick” and one “tack” (length is about 1,4 sec).
This file is triggered every two seconds by setting the K1 input pin of the JQ6500 to LOW with an according Arduino Nano output pin.
To avoid 5V at the JQ6500, for a HIGH at K1 the Arduino pin is simply set to INPUT mode. That is recognized as “not LOW” by the JQ6500 and works just perfect.
That kind of triggering the JQ6500 works fine. At least for some hours/days.
But after that the tick-tock sound randomly starts a kind of stumbling. Sometimes the mp3-file is not played, although the K1 has got a LOW impulse.
As a result, some ticks and tocks are skipped.
Not really good for a clock. 
When I use a new JQ6500 module, everything is well. However, after a few days it shows the same failure.
Have you ever experienced such an strange behaviour?
Is that module not appropriate for frequent triggering every 2 seconds?
As a workaround I am testing longer mp3 samples (e.g. 120 s). Maybe that helps.