HigashiJun wrote: 01 Jun 2023 08:46
Lots of work ahead...
Not as much as I'd thought, but the CD ROM is still a problem.
Ok, I promised pictures, so here we go.
In addition to what I said about the problems I've already homed in on, it looks, based on the corrosion on the metal shield, to have been somewhere damp.
It also had what looked like factory flux all over the board, so I have had to give the whole thing a good clean with IPA to 'de-sticky' it. I did consider it might have been residue from a soft drink, but there was no corrosion thankfully.
First off are the two leaky caps near the CD-ROM busy LED. I originally mistook this for power, but a quick check of the case and it is labelled 'BUSY' so is clearly for the CD-ROM. There is no power LED I can see, which caught me off guard first.
PXL_20230531_194949982.jpg
And here we are with the area cleaned up:
PXL_20230531_195714248.jpg
And with new caps installed and new solder mask to cover the damaged areas:
PXL_20230601_081508308.jpg
I didn't have all of the necessary caps in SMD so used what I had with the same values and a same or higher voltage rating. Luckily the traces are quite thick so using axials was an easy task soldering wise.
I also found that some SMD caps in the video circuit had already been replaced with axial electrolytics, but the job was a poor one, so I removed them and replaced 3 out of 4 with SMDs and the last one with a fresh axial electrolytic, as I didn't have quite enough SMDs either.
Flipping the board over I found this:
PXL_20230531_193102540.jpg
It appears to be part of the video circuit, and looks like liquid damage, but it cleaned up with IPA to a pristine state, and now I get this:
PXL_20230531_221650299.jpg
And comparing it to this from the seller:
Screenshot 2023-06-01 at 09.30.05.png
It's looking good. Interestingly, the video cable for my Dragon 32 works with it. Who knew?
Next I need to look at the CD-ROM, see if I can figure that out, and I need to get a controller and some software to try, otherwise I'm stuck at the loading screen.