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Posted

I tried to build the circuit to use the C64 PSU for my MBSID project, but ran into problems. After first building the circuit, my output voltages were 5,5 V for both the 5 V and 14 V lines. I noticed a break in the circuit, and soldered it. After this, I lost voltage on the 14 V line almost completely (0,2 V or something). When I measured from the PSU plug, the AC lines didn't show any voltage.  ???

Did I just fry my PSU? I haven't opened it yet, and I'm truly hoping that there is a fuse for the 9 VAC line?

Could a voltage regulator soldered in a wrong orientation have caused this? What is the pinout for ST 7809 voltage regulator? I built the circuit assuming that when facing the text printing, the left leg would be pin 1, middle 2, right 3 (the ST logo would be above pin 1).

And what would be the symptoms of fried capacitors?

And should I have connected the "end of the line" cap before I began measuring the circuit?

Thanks!

Posted

Good chance that you fried it, yeah. Just measure it without being connected to the SID if there´s still voltage coming out.

There is a fuse in the PSU (screwed - somewhere at the side), but I don´t know if it reacted soon enough.

Pinout: I don´t know exactly now, but in the schematic/PCB, the big line of the 78xx is the metal on the back.

Fried caps: *BURN* *BOOM* Especially Electrolytic ones.

That end of line cap should be connected, cause it´s filtering the AC out.

Greetz!

Posted

Got some new fuses today, thank God the PSU was ok and I had fried only the 1,6A fuse of the AC side! I'm so relieved about that!

I took the construction apart and started over, adding a part after another. I did nothing different than the first time (well I changed the order of the filter caps on the 9V line, but this shouldn't matter in a parallel wiring, right?). And you know what, the damn thing works now!

So now I'm on the track again. Thanks for the mental support, Pay-C! 8)

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