EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: stgauss on November 18, 2023, 03:47:35 am
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Long story short, cleaning out the attic I found a Panabrator VII wand made in the 80's. Aside from a shoddy wiring fix, it seemed to have a random fault where it would die after 10 or so seconds of operation. Turning it off an on made it work again, but only for another 10-15 seconds. But before tossing it, I decided to tear it down. I've seen several YT channels tear down similar artifacts, but they were all more modern made in china things so it sparked my curiosity to see one that was 30-odd years old.
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What I found inside has me a bit confused, thought I'd post it here to see if someone can explain what I'm looking at. From what I managed to gather this thing's operating at full mains voltage all the way to the motor. I was getting 110VAC on the output lines (left side) that go to the motor. And the speed control wheel worked, but the voltage on output didn't change. Unfortunately a few seconds later I must have F'd the meter leads and I managed to blow up Q2, and the R's next to the ZNR varistor... so that's pretty much all the operating info I got. Nice fireworks show tho.
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From what I'm guessing, the right side is some kind of AC/DC power supply. That square "TJ8A" (part datasheet doesn't show up anywhere) is probably a rectifier chip, the ZNR (K271U) is for overvoltage protection (which probably saved my butt when I messed up the meter leads), and under the 47uF cap is a hidden transistor which I guess is part of the DC power supply.
DC probably feeds the MN4011B chip, from the datasheet that's a NAND gate array. Q2 and Q3 probably work with the speed control wheel, one is NPN the other is PNP. And at the end is a K963 MOSFET and a diode that feeds into the output. And I guess the 902J black part is some kind of coil to control interference.
So, all together, what does it do? Why is there a NAND chip in there? My best guess, seeing that most of the parts are rated for 270V and that I found 110V on the output lines, is that this thing is 110VAC all the way, and there's some kind of a variable frequency drive in there, and the motor speed is controlled via frequency at the output?
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What type of motor does it have? Universal (wound field) or permanent magnet brushed DC? I doubt they'd use an induction/brushless motor in something like this.
It could be rectified DC with PWM, or phase-angle control with an AC motor.
Note that the "6N.2" and "J8.A" are likely Japanese-era date codes.