Hello fellow GDiy members.
I recently acquired a Bokse US-8 Universal Synchronizer. (It converts between different clock formats to synchronize drum machines, sequencers, and synths etc) here is a link to review of the device in SoundOnSound: http://www.muzines.co.uk/articles/synchronicity/1202
Unfortunately it doesn't work - the screen characters are messed up upon power up and the buttons are unresponsive. Flicking on the power fast or slow sometimes changes what happens (blank screen, or different characters light up).
I have little experience in troubleshooting digital devices so i was hoping to ask for advice on where to start. I'm eager to learn, so happy to take advice that makes me study / figure things out.
I have tested the psu for correct voltages (simple 7805 for 5v) using a multimeter, i've yet to check for ripple and noise, will do so when i can get near a scope.
Would testing the clock be a good place to start in a digital circuit (by measuring the appropriate clock pin(s) on the CPU with a scope?)
There appears to be a Zilog Z8 for CPU duties, and an Nec D8279c keyboard / display interface. Most of the other ICs appear to be 4000 series type devices that terminate to the various clock input / outputs, as well as the usual ics you see near Midi ports, i also see a crystal (for the clock).
There are also 2 eproms marked P1 3.3m and Prom2 2.0. I have reseated all of the socketed ICs (CPU / D8279c / PROMS) with no change noted.
I was thinking that possible problems could be:
PSU related (excessive ripple, noise)
Clock related (dead clock / crystal)
CPU related - faulty display driver D8279c, or possibly the Z8 Cpu chip.
Bitrot in the PROMs (lets hope not..
I can't find schematics anywhere on the www. I did find the original designer, who replied to say that he threw out all the documentation 15+ years ago!
I could take a photo of the pcb assembly if that helps identify things to look at.
Thanks for your time!
I recently acquired a Bokse US-8 Universal Synchronizer. (It converts between different clock formats to synchronize drum machines, sequencers, and synths etc) here is a link to review of the device in SoundOnSound: http://www.muzines.co.uk/articles/synchronicity/1202
Unfortunately it doesn't work - the screen characters are messed up upon power up and the buttons are unresponsive. Flicking on the power fast or slow sometimes changes what happens (blank screen, or different characters light up).
I have little experience in troubleshooting digital devices so i was hoping to ask for advice on where to start. I'm eager to learn, so happy to take advice that makes me study / figure things out.
I have tested the psu for correct voltages (simple 7805 for 5v) using a multimeter, i've yet to check for ripple and noise, will do so when i can get near a scope.
Would testing the clock be a good place to start in a digital circuit (by measuring the appropriate clock pin(s) on the CPU with a scope?)
There appears to be a Zilog Z8 for CPU duties, and an Nec D8279c keyboard / display interface. Most of the other ICs appear to be 4000 series type devices that terminate to the various clock input / outputs, as well as the usual ics you see near Midi ports, i also see a crystal (for the clock).
There are also 2 eproms marked P1 3.3m and Prom2 2.0. I have reseated all of the socketed ICs (CPU / D8279c / PROMS) with no change noted.
I was thinking that possible problems could be:
PSU related (excessive ripple, noise)
Clock related (dead clock / crystal)
CPU related - faulty display driver D8279c, or possibly the Z8 Cpu chip.
Bitrot in the PROMs (lets hope not..
I can't find schematics anywhere on the www. I did find the original designer, who replied to say that he threw out all the documentation 15+ years ago!
I could take a photo of the pcb assembly if that helps identify things to look at.
Thanks for your time!
