Roland JV35 no output

Hello all! I have a JV35 that has only a faint output at the left headphone channel. I have replaced all electrolytic caps, but no help. I set keyboard to DAC test mode. On scope i see signal at ADC U11 L and R, however it is only about 200mVpp. Does anyone have an idea how large this signal should be? This ac signal is not detected on the out side of serial capacitors C54 and C60, but 1.5V DC offset is blocked. Am stumped at this point.

Good morning,
Are the L and R output jacks also unbalanced ?

There is no output at all at the L and R output jacks. The synth was loaned to some teens with a band. We suspect they connected something wrong to mess up the unit. All DC voltages on the board measure ok. The ADC has a measured Vref of 2.71VDC. No signal reaches the low pass filters, from the ADC.

Between the DAC and the outputs, there is only IC14, the volume potentiometer, IC12 (IC13 for the headphones), and possibly transistors Q6 to Q9.
If you have a signal at the DAC output, check IC12, the NJM4565 are not immortal !

Hey Didier, thank you for helping me troubleshoot this synth. There is not much debugging info for this on the web. They must be reliable. ?

So looking at the schematic, the low pass filter is the next in signal flow. There is no signal at the inputs or outputs of IC14A or B, with the DAC test 440Hz running. So possibly IC14 is bad and shorting out the signal? So then removed the series R46 in front of IC14A input. No signal detected on either of the R46 pads. Probing further back towards the DC blocking cap C60, signal detected on DAC side of C60, the other term shows only that DC was blocked. At this point the small 200mVp-p signal isn’t seen by my oscope downstream of C60. My scope is old, but I should see something on 100mV/div scale. Or is the DAC (s) bad for too small a signal?

Good morning,
I have a JV-30 which is structured identically at the output, the DAC is not the same, it is a µPD6376-GS-E2 (16 bits).
Measurements carried out in Test mode (DAC check) :

Didier, Your measurements were very enlightening. It makes sense that the same topology is used on both JV50 and JV35/50. Also, that Roland would use a low output signal as a DAC test. Unfortunately the oscope I have cannot resolve these signals. Got to get this off my bench.
Thanks again for your help.