Roland JX8P no sound

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Joined: Wed Dec 07, 2016 6:05 am
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Location: Sweden

Re: Roland JX8P no sound

Post by jxalex » Fri Feb 03, 2017 2:55 pm

I suspect that some capacitors are bad which are leaking DC or short circuited.

Check the outputs of the oscillators output for signal change.
If having no oscilloscope then just do a probe with a cable which You connect to soundcard input just to listen the sound change, or amplifier input (just put 0.1uF capacitor, following the 100k resistor between the input and the probe so that You wont change the DC mode).

Check all the voltages around the oscillators if they get proper DC . Also check the circuit board for bad solder joints.
These can happen due to the age.

what DC level is at TP5... ? for example if You measure with multimeter what it shows ?

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Joined: Tue May 16, 2017 5:55 pm
Gear: ADT-5MT 32/64 channel mixing console, Roland D-50, JX-8P, JV-90, R8m, Yamaha TG77, MoXF8, lots of outboard and vintage mics
Location: Germany

Re: Roland JX8P no sound

Post by bernbrue » Sat Aug 05, 2017 8:49 pm

Just bought a Jx8p with the same problem, no output. I checked everything (voltages etc.), everything is fine. I haven't checked if there is any signal at TP5. Any idea!

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Joined: Thu Nov 01, 2018 8:35 pm

Re: Roland JX8P no sound

Post by goyousalukis » Thu Nov 01, 2018 8:53 pm

Hi guys,
I just got a JX8P with the same symptoms - just digital noise at the output and TP5. All my voltages are correct, and it does countdown. I can change synth parameters and patches, but no MIDI activity either way. As with the OP, when I change patches, the noise changes, and when I press keys, there is a high frequency noise that changes with the pitch. The only thing funny I found was that during the original assembly, someone dropped a test point lead on the board, and it got soldered to one leg of a capacitor, and the other leg was just a hair away from touching the other leg. Of course, I removed it, but that was never a problem over the life of the synth.

I was curious if the original poster ever resolved his issue.

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Joined: Sat Aug 22, 2020 5:15 am

Re: Roland JX8P no sound

Post by leonimus_666 » Sat Aug 22, 2020 8:52 pm

hi, i got a jx8p, its "A" voice is off, i suspect the problem is related to the ir3r05 filter chip,
since i can trace the signal there. In pin 6 (load) of this chip I find a 3 Mhz signal that is -3 v
with respect to the other functional voices, which oscillate around 0 v. I would like to obtain more
information about this chip @rasputin, you have provided some diagrams of that chip that are helpful,
I would like to know if you have something else about it. Thanks

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