IR3M02 from Sharp Corporation. Find the PDF Datasheet, Specifications and Distributor Information. IR3M02 Pulse Width Modulation Type Switching Regulator Contrl ic. Details, datasheet, quote on part number: IR3M Electronic component datasheet for IR3M02 manufacturer SHARP. Free doqnload!.
Some PSUs have a protective “crowbar” overvoltage circuit, but it’s been a long time since I’ve seen one of those fail. I still advise being accurate on it’s value.
It was hard soldering when I was tipsy but I never told my boss Your power supply is shutting down due to an overvoltage condition. Does this make sense?
You might datasheey to desolder the D1 bridge to measure with a diode check because of the capacitors and T1. When you measured did you have the switch connected to the board, Do you still get a constant Ohms reading when measuring across the 2 pins on the board with switch not connected, PSU not plugged in and caps drained. What is the AC across the blue?
I think i can just about see where your are going. Yes – looking at your drawing again. Dztasheet like an 80V loss which seems to be the increase you are datasheett across the caps so maybe the excess current is passing thru the rectifier bridge. Be sure and measure the AC across C1 and C2 which should be the same.
Most of my troubleshooting back in the day was using my scope as a DC meter also. There are 2 ceramic power resistors. The main caps are ur3m02 bulged, yet V an allits just the light. Your AC should be plugged into the other connector where the fuse is.
That kick is just from the start up catasheet. Or possibly one of those step-down transformers used for portable power tools in the UK?
Datasheeets & Application Notes
Its probably just old. Then check the comparator ICs, each probably contains two or more comparators, each has two inputs and one output. That’s way too much. If one of those fails, it’s usually as a short.
The faq you referenced should have the jumper J1 removed for VAC operation. Yes the equivalent of j1 is removed, but i am still getting VDC? Yea, without a schematic I’m clueless at this point.
Japanese date codes | Electronics Forums
Yup some manufactures put the value on the cap as is, 2. I do have one of those power tool transformers, its at my garage though, so i will have to pick it up. Thanks Chuck Gnow for a question you may have guessed coming: I cant think the LM is too fussy about 18V exactly, because if it did this power supply design as far as i can tell would require a VAC source in V mode. Otherwise I think you will have a difficult job in reviving your power supply.
Look at the sample Chuck provided. The fact that the fan spins temporarily then stops indicates the power supply is starting up then shutting down due to a fault. The voltage selector switch actually reads ohms when in V, not sure if that’s by design or 20 years or corrosion. I had been stuck all afternoon on a TV tough-dog problem. One time a coworker and I were doing overtime work in the evening. Sorry to sound vague but this is a bit out of my league. Connect DC supply via a current limiting resistor eg ohms to SMPS IC – check voltage on each IC to determine that supply is within range, increase DC voltage until all ICs are powered up, check voltage drop across current limiting resistor for current drain.
Larry Yes sorry, its not clear in the pics. So this would indicate T1 is at fault right? The AC circuit is pretty simple. T1 secondary yellow is center tapped white using D5 and D6 as full wave bridge filtered by C11 purple. Its a familiar number daatsheet me to do with 3-phase, so I will have to look here a bit more closely, perhaps the rectifier is screwy. Just jumper it if needed.