I am testing a circuit. Until my recent aquisition of a high quality meter, my reading were all over the place. Now I can see only what my circuit is doing.
I have 4 PCBs from a 1980s roland synthesizer. One of the boards is defective. I refeenced against two working boards in my other synthesizer. I have identified a board that it not common with the other 3. In the logic circuit from 5V to ground, I have a resistance of 5.9 ohms in three of the boards. In the one that I think is defective, the resistance is 2 ohms. It climbs to 5.9 and then drops steadily to nil. It is consistent, with repeated tests. Which type of component would most likely cause this?
I have 4 PCBs from a 1980s roland synthesizer. One of the boards is defective. I refeenced against two working boards in my other synthesizer. I have identified a board that it not common with the other 3. In the logic circuit from 5V to ground, I have a resistance of 5.9 ohms in three of the boards. In the one that I think is defective, the resistance is 2 ohms. It climbs to 5.9 and then drops steadily to nil. It is consistent, with repeated tests. Which type of component would most likely cause this?
I presume these power supply assemblies are being tested after removal from the synthesizers. I.e., they are not electrically connected to any other circuitry.
It sounds like your problem may be related to a capacitor. Don't assume it's a defective (shorted) capacitor - it could be, but it could also be a problem in a portion of the circuit that isn't "seen" by your ohmmeter until after a capacitor charges.
It goes without saying that a schematic would be VERY helpful. If you don't have one, perhaps somebody else can provide the applicable portion. Or seed a search engine with something like "roland synthesizer schematic" and see if there's an online source for your model.
Dale
It sounds like your problem may be related to a capacitor. Don't assume it's a defective (shorted) capacitor - it could be, but it could also be a problem in a portion of the circuit that isn't "seen" by your ohmmeter until after a capacitor charges.
It goes without saying that a schematic would be VERY helpful. If you don't have one, perhaps somebody else can provide the applicable portion. Or seed a search engine with something like "roland synthesizer schematic" and see if there's an online source for your model.
Dale
When you need help, specify what you are working on. "1980s Roland" doesn;t tell us much . DW8000 tells us exactly what you have, then we can find schematics. Please provide the model number or name.
Your +5v is loaded down? Isolate it to one board if you can. If this is the same unit you are seeking connectors for, MAKE SURE all the little cables are on the right connectors. A cap can be shorted, either a small electrolytic or one of the tiny film or ceramic caps by each IC. But an IC could also be shorted instead.. And other possibilities remain.
Your +5v is loaded down? Isolate it to one board if you can. If this is the same unit you are seeking connectors for, MAKE SURE all the little cables are on the right connectors. A cap can be shorted, either a small electrolytic or one of the tiny film or ceramic caps by each IC. But an IC could also be shorted instead.. And other possibilities remain.
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