Sunday, July 5, 2009


the over heating issue was caused (as could be logically ssumed) from the installation of the VFD module. the VFD module was drawing far to much power.. even when that board wasnt plugged ing.. and making the voice board overheat. i didnt loook at it this way : on the back of the vs is a printed power total by the fuse " 500ma@110v" max draw. so i then look at the vfd "150-200ma" max draw alone! shit. thats just under half the power for the vfd alone. duh. good thing i dont build rockets. anyway so i reinstall the old burnt out lcd and things work for hours. he ps section ets hot but not like it did, and not as fast. all functions work as they should as well. the new switches are great.

so im thinking that i should maybe figure out how to add more amperage (say take the ps supply up to 1a or so and then the vfd should be coolio.. or add an external hack (walwart adapter ) for the VFD section power, im not sure how the migleing of power supplies works.. and it it is seperate from the mains or not. id probubly have to cut traces to make sure that the external is isolated from the mains. so its back to the burnt out (BUT WORKING) prophet vs. such is life...

but on a positive note. its better than a non working vs and the dx-7 IIFD restoration came out excellent as well (new display-from a tx-16w) and all new 3mm tactile switches. its fantastic and its fun to programm with the butons! DESPITE WHAT 20 YEARS OF BAD PRESS SAYS!!!!! its not really that hard. try it!

Friday, July 3, 2009

prophet vs- the next trial

well , i did all e work. i re-capped the power suplly section, put new voltage regulators, and installed the VFD. the vfd has caused a small issue: it sits like .5mm higher than the old LCD, so i checked the board behind the old LCD area, kucily it was a huge, blank field of open PCB. so i drilled to holed thru the board to accomodate the "taller" compoments on the back of the VFD board. problem solved. now all switches sit as they really should.

enter the next test: power section heats up INCREDIBLY fast. ugh. ok so unplug all boards and slowly plug them in to see whats causing the issue If you guessed the VFD was the issue - YOURE WRONG! its the voicing board (uh-oh) since it contains some of the super rare CEM chips. luckily none of them were smoking hot. the 2 voltage resistors on that board (7805 an 7905) positive and negative 5 volt regulators are the issue.. the negative one gets untouchable. red flag. no good. i left it on with the switch/display section on for like an hour : normal heat level on the ps. i turn the voincing board on and in like 5 monutes the ps is too hot to touch. not good. so i had to order the regulators (50 cent parts) from mouser electronics. only took 3 days to get here but.. still. i hate the fact that there are no more mom and pop electronic supply places left. anyway i ll try them out in there today and see if the solve the issue. im crossing my figers...