Dear Chris,
thank you very much for your help.
I tried it right away, and you are right, the sound on the AUX OUT output is OK, on both sides, under all conditions.
Regarding the master volume dial, I think it is not related to the issue. If the left side sounds fine, no matter how I turn the volume, the left side sounds fine. If it doesn't, no matter how I turn (how often, how fast etc) the volume, it still doesn't sound. So it's not the "usual" potentiometer problem.
The volume knob has no effect on the problem, but tapping the lower left - left rear of the body of the instrument will trigger the fault or solve it. Somewhere below or behind the "Mic" and "Song" buttons - area.
What are the chances of finding some faulty cable soldering there? Or is it on all PCBs?
Hi fis,
I rate the chances of finding and fixing the fault as relatively high.
If I were you, I would unscrew the Tyros4 and first check whether the wide connector on the
MICVR board (on which the master volume control and the mic gain control are located) has good electrical contact (e.g. pull it out and plug it back in several times).
Then trace the route of the white cable bundles from the MICVR board to the AJACK board (where the Line Out jacks are) and check the cable connectors there as well. (See the two attached pictures.)
Cables also go from the AJACK board to the DM board (mainboard). If you haven't had any success yet, I would also check these connectors on the DM board. (The sheet metal cover would have to be removed for this.)
But before that, please make sure to watch the following YT video. This also shows how to open the T4.
>>>
https://www.youtube.com/watch?v=iaxE4i9x_S4I suspect it's the mentioned connector on the MICVR board, especially since you wrote that the fault responds to "tapping the lower left - left rear".
Very important: Before you touch electronic components / boards inside the T4, you should definitely (just before) discharge your body by touching a grounded metal part with both hands (e.g. bare part of the central heating or water tap). Then, if possible, do not walk on carpeted floor so you don't get static electricity again.
I hope you can fix the issue!
Best regards,
Chris
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