My thoughts are a disturbed connection in transit. It happened to me with a spectrum analyser once. Also, an old CRT monitor I dug out wouldn't work but started to do so when I was checking connections. I was once sent to Dubai to fault find a brand new broadcast transmitter which started working when I put my multimeter on one of the connectors. Connections are a PITA.
So pull off any connectors and re-connect them, using contact cleaner if you have some. The same applies to any socketed parts although pushing them firmly in their sockets often does the trick.
Regards
Keith
No signal generators/oscilloscopes but several multimeters one of which has limited ability to measure frequencies but not like a good scope. I see 2 eproms seated very firmly doesn't look like anyone ever touched this inside. Main cpu and ram/rom is surface mount not socketed. I've also tried my own coldboot technique-connecting the internal battery + to ground without ac power to see if this might clear any jumbled memory reading writing. This worked on an ancient general music keyboard but not here. There are 3 mainboards one of which I haven't checked. The original owner maintained something happened during shipping but I've seen no documentation that UPS, FedEx or post office uses any scanning that might effect memory chips or cpus. This was sent UPS. It does look like something has messed the basic os, the unit itself looks well taken care of not abused. I'm getting no sounds at all as well. I'll implement your suggestions and thanks for the trigger schematics, very nice!
On Dec 12, 2015 10:39 AM, "keith@... [DTXpress]" <DTXpress@yahoogroups.com> wrote:I may have a service manual but won't be able to check until Tuesday. A simple bad connection could give you the symptoms you describe if it has a microprocessor with external program memory - it depends on what is inside the box. If there is a socketed EPROM, try removing and reinserting it. Check voltages - I would guess it is 5V inside, the DTXpress is.
What diagnostic equipment do you have?
Regards
KeithPosted by: keith@kdel.co.ukReply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (16)