[sdiy] Jupiter 8 doesn't boot

Gil W. gil_we at yahoo.com
Mon May 21 00:05:56 CEST 2012

It's interesting as I just read Mike's post about his JP6 no functioning.

My JP8 has given me no issues at all up until today, when I powered it on, it booted up just fine, showing the running led sequence 4 times as always, but then a few seconds after than, the LED screen went blank, with all button leds also shutting down, except for the two LFO leds, which blinks with no logical sequence... Tweaking the LFO by moving their sliders doesn't make any change in their behaviour.

I already checked the main voltages (+15, -15, +5) which were fine. I reseat all connectors. No change.

One thing which was interesting is that I pushed the 3 ROM chips a bit inside, and still all LEDs were dead but the LFO leds did function move in a logical sequence (constant rate) - but the next power up, they stopped moving in a constant sequence :/

I really don't know were to start as I don't even have any oscilloscope ion hand, only a DVM.

I read your comments about the JP6 problem Mike has, which is quite similar to my JP8, telling there's a specific transistor which tends to fail. I see a 2SC1815 all over in the JP8. Is it also a notorious part in that means ?

Thanks for any help !

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