Fixing A Matsusada RK20-20 power supply.
2x devices blown on the primary switcher circuit only id is code 00.15.0600 TO3PN3 caseI'm thinking these are IGBT's rather than Mosfets but guesswork as they are wrecked. Any ideas? Code might indicate 15Amp 600Volt? :) feeling lucky?
Small driver board is encapsulated in RTV silicon goop, hopefully not damaged but haven't got that far.
TIA JC
It could be my imagination but there seems to be some characters printed on the more lightly coloured rectangle. If you have a powerful lens with you, see if there's anything to read by varying the angles of viewing and lighting. Perpendicular is not always the best.
I use a lens salvaged from a 16mm film projector and have often succeeded in identifying devices that at first don't seem to have anything on them. That includes markings that had been rubbed off, faded with age or burnt away from overheating.
Yes, I also thought that but I think its just overheating. I can't bring up any image from them. These are the only parts in this unit with obscure ID's so could be selected parts, sux. JC
Drive IC is a FUJI 5502M , Probably FUJI MOSFETS, wired in parallel. JC
If this is an SMPS it should never be really hot. The only things that can cause that are an overload or not enough drive.
If you really can't get a print you have to ear reverse engineering. To kno w the output terminals, now get to know the input terminals.
Figure out if it has a shunt resistor and/or a series resistor, and determi ne where that is coming from. You figure out what kind of drive it needs an d you figure out the device. Then you can work on a replacement.
Termy secret 25. Take about a hundred watt audio amp, hook u a generator an d feed it with like 3KHz. Almost anything will work. But crank it out ad se e if you get the voltages on the other end.
The reason I say to do this live test, even if it is a bit of a bitch to do it is because if it is not bipolar drive problems are rare.
Before SMPSes came into vogue I used to use a variac. Just feed ANY winding of that transformer and see what happens. I think you are going to find so mething shorted. HA, if you got a good enough amp you can make the smoke co me out and find the bad part quick.
I made a good life out of fixing what others could not. Now you don't have to buy a function generator, if you got a smartphone there is a app for tha t. You get a plug, plug it into a stereo with respectable power, and you go t yourself a dandy piece of test equipment there.
if you need a 100 WPC amp I can sell you one for fifty bucks, but what it c osts to ship might be out of this world. You got Craigslist where you are ? Deal locally in cash. Best way. Paranoid ? Get a gun.
Actually for the best bang for the buck get a Crow. Audiophiles don't seem to like them so they are not that expensive and you ru them into a short ci rcuit they do not fry. They might trip a circuit breaker at your electric p anel but they will be fine.
I have more advanced methods, but no time to type them out Just try that. T HEN we talk about the transistors, I will need to know just how they are dr iven and you will have to run it and have it at east try to start to see wh at it puts on those gates or bases or whatever they have. That will tell us . Then we got it. All we have to do is accommodate it...
snip snip :)
Well yes, but in my experience SMPS run great until something goes wrong/ out of spec, then death. This is a $K bench supply so can't go crazy on it.
JC
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