CD-ROM2 with stactic/cracking noise while playing audio

[Alexei]

I have a CD-ROM2 drive with strange behavior. I've searched the forum but haven't found a solution.

When I play an audio CD, there's background noise, like static/crackle interference. This happens through the headphone jack, the rear line out, and also from the interactive player when I connect the CD-ROM drive to the PC Engine using the iFU interface.

I've replaced all the capacitors; it was a fairly clean and straightforward job. At first glance, I don't see any corrosion damage, so I'm stuck on this point...

I've also noticed that the CD-ROM drive's display, where the track number appears, flickers slightly, as if there were a power supply issue or a damaged capacitor, but the capacitors are new (Console 5 kit) and should be fine, and I'm using a good power supply (Triad brand)

I don't have any games to test with at the moment.

I would be very grateful and happy to try anything you suggest. I have another faulty board from which I could salvage any components..

Thanks, gentlemen!

[Keith Courage]

Do audio tracks ever stop playing prematurely?

Crackling can be the sign of a lens requiring adjustment.

Are you testing with a real audio disc or a CDR?

Does this happen when using the CD drive by itself(not in the docking station) as well as docked?

This could also be an under power problem. What power supply are you using?

[Alexei]

Do audio tracks ever stop playing prematurely?

Crackling can be the sign of a lens requiring adjustment.

Are you testing with a real audio disc or a CDR?

Does this happen when using the CD drive by itself(not in the docking station) as well as docked?

This could also be an under power problem. What power supply are you using?

Thanks for the help. I'm using original audio CDs and have tried two lenses with the exact same result. The music plays correctly, but there's always background noise/interference. I've captured a video to show the problem:

I'm using a 9V, 2.5A TRIAD power supply.

The noise is also present when using CDROM2 independently, both through the main jack and the rear line out.

EDIT:
I've checked the power supply. CDROM2 is receiving 9.36V, and the measurements at its voltage regulator are 8.5V input (approximately; I forgot to write it down) and 5.1V output.

[Alexei]

I still haven't solved the problem. Things I've tried:

Adjusting the potentiometers only improves/worsens CD reading, but the problematic noise is always there; the potentiometers don't affect it.

I cleaned and inspected the entire board with a microscope. I didn't see any corrosion or damaged traces. I can't rule out the possibility of a loose trace, but in this initial inspection, I wasn't able to find anything wrong.

I replaced the headphone jack and the power barrel jack because they weren't in good condition. This obviously didn't solve anything, but it was necessary.

I reflowed all the chips on the board. No change; the problem persists.

For me, it's time to follow the advice of those who know this hardware and share my experience in case it helps someone in the future. I read about some integrated circuits you call op amp 4558; I don't know if they're related, but I'll take measurements and post them tomorrow.

Thank you all for your time!

[Alexei]

Hi everyone, I haven't had time to investigate further, but I've noticed two points that are connected, which I don't think they should be.

Is this a possible short circuit, or is it normal operation?



EDIT:

I disconnected the brown wire.

On the main board, the points where the brown and red wires connect are no longer making contact.

On the top mini-board, there is still contact between the red and brown wires.

Sorry if my explanation is confusing; I'm not used to giving technical explanations in English, haha.

EDIT 2:

No luck, the problem persists. Apparently, the last time I opened the unit, a short circuit occurred due to a speck of metal residue, which is why the red and brown wires shorted out, but this is unrelated to the sound problem with this unit.

[Alexei]

Good afternoon, gentlemen. I've taken some measurements; I'm not sure if they're good values, but it seems IC 103 is damaged.

CDROM2 Board 3184-1-72931843-1

IC202 4560

1 2.25v
2 2.25v
3 2.25v
4 GND

5 2.25v
6 2.25v
7 2.25v
8 7.8v


IC203 4558

1 3.93v      
2 3.92v
3 3.93v
4 GND

5 3.92v
6 3.93v
7 3.92v
8 7.81v



IC204 4558

1 4.3v
2 4.31v   
3 4.27v      
4 GND

5 4.27v
6 4.31v
7 4.31v
8 7.83V


IC103 4558

I'm having a hard time taking measurements on this IC.

Voltage on pin 1 is not stable; it fluctuates between 3.5V and 4.5V.
I'm not getting readings on pins 2 and 3.

4 GND

5 4.27V
6 4.27V
7 6V
8 8.57V


EDIT:

Near IC103, which I suspect is faulty, I found capacitor C138 shorted. Outside the screenshot area, C137 is also shorted.



These two capacitors are located directly below one of the BA chips.

[Keith Courage]

Sorry, I've been peoccupied with Car repair lately and just now got a chnace to listen to your video.

I can say that Ive never heard that from one of these drives before.

I have however heard loud static in between loading of games when testing an actual game disc. The culprit for that was a broken resister found near the 1 Screw that holds the main board in place inside the case(near the center of the board). I'd start taking a look at resisters to see if any are bad or cracked.