exxos's Atari, Amiga & retro forum

Tomswork wrote: 25 Jul 2023 00:03 It destroyes the os while running and crashs reinstall fixes it for a while. Bad drive bad ram it's a hunt

Tom

Bad drive should be simple to figure, swap out and reinstall. Could be RAM too, you could try the UART method to see if there are any fault codes.

So, I picked up another PS4 for spares, supposedly no power and possible liquid damage. It arrived today and is incredibly dusty, however I tested with a spare PSU and it powers on to a white light. There is no video output sadly, but a white light is a good place to start, and at least I have the other Blue Light Of Death board for spares.

There are minor indictors of liquid on the mainboard, but nothing terrible, and certainly easy to clean.

Looking at the original PSU, I found this:


And this underneath:


Which is likely why there is no power from the thing. I need to compare with my working PSU to see what the IC is and if any of the traces have evaporated. I suspect that this was a short caused by liquid, based on what I can see.

As for the video, I suspect the HDMI encoder is bad since the HDMI port is in good order and there are no signs of damage to it or its connections, and no signs of corrosion.

Well, that chip certainly went bang!

stephen_usher wrote: 28 Jul 2023 16:22 Well, that chip certainly went bang!

That it did.

Underside of the good PSU for reference:


Versus bad after cleanup:


I think I may have got lucky, I'm not seeing any trace damage, nevertheless I'll get it under the microscope to be sure and will clean up what look like 'flashover' marks before I fit a new one and pust some fresh conformal coating on there. I'll test out the 3 caps too.

At least there is a schematic available for it.

Looks like a couple of dry joints on those pins to the right of the 3 caps. Hopefully you just need another chip and then off you go.

PhilC wrote: 28 Jul 2023 17:47 Looks like a couple of dry joints on those pins to the right of the 3 caps. Hopefully you just need another chip and then off you go.

Those pins are part of the chip, so will all be getting cleaned up ready for the new one. I'll look at all the joints in that area to make sure they are good.

So, everything has cleaned up nicely:


And even the flash marks are gone. BUT, ZD22, C27, C28 and C61 are all toast, so I'll have to order them today. I have tested other nearby components as far as possible and so far so good. Let's hope I can fix it.

So, parts are on order for PSU no 2 and I'll get round to that later, but next is the 2nd PS4 that gets to the white light.

A white light usually means it's booted, which is good, but no video output can often mean that the HDMI EMI filters are bad, or the HDMI encoder has died.

Since these may have been fried by the PSU going pop, I am going to raid them from PS4 no 1, which has the far more serious blue light of death and may be unrepairable.

I've prepped the board ready to receive the parts:


2 of the EMI filters were obviously damaged, so I think they definitely require replacements, which are coming from here:


Because the EMI filters have no markings, I painted one end silver to ensure correct orientation when I remove them and transfer over to PS4 no 2. As for the encoder, I'll remove that once I've transferred the EMI filters, using hot air.

I'll install using drag soldering though, as I think overall that'll be safer than using hot air again, especially since I don't want to disturb the EMI filters.

So, HDMI circuit is rebuilt with replacement EMI filters and replacement HDMI encoder:


But still no video, though the machine will go boot up apparently normally and will still go into safe mode. More research into what it could be required.

I did check for shorts on both the HDMI encoder and the EMI filters, and the EMI filters have continuity where they should, but I'll do it again befor I move onto the next thing. I guess now the HDMI encoder I removed may actually be ok, so I'll keep it to hand for now.

Fascinating stuff so far!