I'm looking for a schematic or service manual for a dbx Model 500 Subharmonic Synthesizer. Seems like there's nothing out there for it. It's somewhat similar to the Model 100 schematic, but even then, it seems like the Model 100 schematic circulating online is incomplete.
Mine is from 1980 based on component date codes. It belonged to my late brother and was just left on a shelf. He used to be a DJ, and I know he used these back in the late 70s and early 80s. But I have no idea of the history of this one. A friend of mine has been after me about wanting to buy it, so I finally pulled it out to test it. I brought it up to power slowly to increase odds of it not blowing up, and I replaced two electrolytic caps that were marginal. But I get some odd readings from 2-3 BJT transistors on diode tests.
If there's no schematic, is there any tech out there who's an expert on repairing vintage dbx gear? This is not the kind of headache I need right now.
Mine is from 1980 based on component date codes. It belonged to my late brother and was just left on a shelf. He used to be a DJ, and I know he used these back in the late 70s and early 80s. But I have no idea of the history of this one. A friend of mine has been after me about wanting to buy it, so I finally pulled it out to test it. I brought it up to power slowly to increase odds of it not blowing up, and I replaced two electrolytic caps that were marginal. But I get some odd readings from 2-3 BJT transistors on diode tests.
If there's no schematic, is there any tech out there who's an expert on repairing vintage dbx gear? This is not the kind of headache I need right now.
I don't know if it is similar, but you can find the service manual of the DBX 120X-DS and 120XP on the internet. The 120 mainly consists of opamps and the frequency halving is performed by flip-flops. The CD4013 flip-flop drives a 2N3904 transistor at the subsonic frequency and makes it either conduct or not, which determines whether an opamp circuit is inverting or non-inverting. The audio signal that has passed through this opamp is filtered and becomes the synthesized subharmonic.
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Check with service centers for repair options, or they may sell you a service manual.
https://dbxpro.com/support/repairs?geo=us&state=ca
https://dbxpro.com/support/repairs?geo=us&state=ca