Re: [oldsynth] omni power supply woes
2002-02-14 by Peter Brown
hi all, i replaced the LM723 voltage regulator, and the power supply is working again! the synth is even making some sounds (with some remaining bugs which i will document in a separate posting)...for the benefit of others who might have the same problem now or in the future, here is a summary of the problem & solution: problem: no voltage from power supply due to short which occurred while manipulating keyboard connector while power was on (bad idea) symptoms: smoke from 4.7 ohm resistor (R10 if you're keeping score) immediately following incident, followed by loss of power solution: -replaced R10, along with tantalum caps (two 10uF 35v, one 1uF 35v) -replaced LM301 op amp -replaced LM723 voltage regulator, and 1A4001 diodes thanks again to all who responded, PB>> On Mon, 11 Feb 2002, greg montalbano wrote: > Sounds more like a problem with your regulators. If you can do a web > search & come up with a pointer towards the power supply schematic, I can > be more specific in talking you through it. > Meanwhile, DISCONNECT the output of the power supply from the synthesizer > before testing any further -- power supply components are fairly > inexpensive & easily obtainable; the synth parts are another matter, and > should not be risked. > > ~GMM > > At 10:29 PM 2/11/02 +0100, you wrote: > >hi all, > > > >i was wondering if anyone has any suggestions about diagnosing/fixing a > >power supply problem on an arp omni mk1... > >etc. etc... -- Peter Brown Senior Software Engineer Dept. of Computer Science 140 Governors Drive University of Massachusetts Amherst, MA 01003-4610 Phone: (413) 577-2505 Fax: (413) 545-1249 pbrown@... http://www.cs.umass.edu/~pbrown ARP Omni : http://parsley.cs.umass.edu/pbrown/arp Resource Page :