JX-8P Voltage Problem
2015-06-13 by david@...
I have a Roland JX-8P that works fine except all voices are distorted, not with noise but like the frequency is too high or something. After some testing, I found that the voltages on the large connector of the PSU were off.
I tested the voltages and this is what I get starting with the blue wire on the large connector
-8, -8, +15, +15, g, g, g, g, g, +9, +5, +5
And the small connector:
-15, +15, g
Everything is correct there except that the -8's should be -15's. Thinking it was the PSU, I replaced it with a known working one. Same problem. If I disconnect the large connector from the mainboard, the -8's go back to -15's.
With the connector back on, I get -15V when I first power it on but as soon as it's done with the countdown, the voltage gradually drops to -8 within a couple of seconds. I disconnected that connector from the mainboard and it stays at -15V consistently. So, the problem must be something on the mainboard that's causing the voltage to drop. Also, when it's first done counting down, the sound is normal for a split second and then gradually goes bad. It almost sounds like a filter sweep. I am not a technician so I don't know where to go next. Any ideas?
I tested the voltages and this is what I get starting with the blue wire on the large connector
-8, -8, +15, +15, g, g, g, g, g, +9, +5, +5
And the small connector:
-15, +15, g
Everything is correct there except that the -8's should be -15's. Thinking it was the PSU, I replaced it with a known working one. Same problem. If I disconnect the large connector from the mainboard, the -8's go back to -15's.
With the connector back on, I get -15V when I first power it on but as soon as it's done with the countdown, the voltage gradually drops to -8 within a couple of seconds. I disconnected that connector from the mainboard and it stays at -15V consistently. So, the problem must be something on the mainboard that's causing the voltage to drop. Also, when it's first done counting down, the sound is normal for a split second and then gradually goes bad. It almost sounds like a filter sweep. I am not a technician so I don't know where to go next. Any ideas?