Hello all, I've messaged this on Tony_G's youtube and I might as well mention this here too. I'm hoping to get CuriousMarc's attention on this as well. I essentially found a flaw with the floppy/cd drive area. Mainly the floppy. Could have an effect on the CD, I haven't confirmed. The flaw has to do with the ribbon cable of the floppy and the ribbon connector of the IDE/power to ribbon cable PCB adapter.
In the following pictures you'll see that the adapter is flipped upside down and close to the chassis. Its so close that if you so much as overtighten the nuts holding the adapter down, the ribbon cable could come into contact with the chassis. Also the flex on the ribbon cable matters as well.
What is happening here is that the ribbon cable's pins are not fully inside the connector. They are partially exposed! Sandwiched between the connector and chassis, the power rails and the data rails will have no problem with a short to ground resulting in a blown power rail (what happened to me and the best case imo) or data pins going low causing data corruption (worse case if your are reading/writing)
Post repair. Hard to see but what you see on the floppy side is about what you see on the adapter side. Solution to problem pictured.
During repair. I had to desolder the connector and repair the trace, cutting out pieces of copper and soldering them. Kinda lucked out.
https://flic.kr/s/aHsmejnZL8Album where I have pictures stored. I apologize for the less than ideal pictures. I didn't have the forsight nor the time to snapshot during repair.
Now in some cases if its not disturbed (ie. moved around when powered on) you could have a functional floppy drive. I believe that is what is happening here when the drive was replaced or in Marc's cautious care. However, you'll still run the risk of breaking this area if you don't properly fix this problem. That or a seller/another end user can power the unit not knowing any better.
The solution I did was cheap and easy (maybe not the most long time solution if something eats at it).
I basically put an orange sticky note as an insulator. A proper long term solution would be to get the
same type of insulating plastic you see all over the case inside. Just be careful tightening the adapter back into place.
Back to the videos, one of the questions I'd like to ask is where did you get the replacement CD drive? I searched before but couldn't find any. Maybe I'm not searching right?