PC-Engine DUO only recognizes CD-Audio - NO LASER OR POT ISSUE

[smups]

Amazing, I thought the board was clean!
I did what you said and it's working, like you it did take a couple attempts.
I just need to tune the laser a little more but most of the games work fine.

I get a whistling noise on two games when they are trying to load.

Thank you!

[Vimtoman]

Good to hear.

It's amazing how much stays on.
I've found doing a dishwash and then an Alcohol clean is the only way.
Sometimes like yours and my last Duo it need another clean.

[smups]

Tuned the pots and it is now spot on.
Can't believe I spent hours on this and it was fluid under the chips.
Live and learn!

[Xenogears]

So here are my lastet results: the PC-Engine DUO still reads Audio-CD, skips Tracks, shows Playtime, remaining Time and has no issues. If I insert a Data Disk, it keeps start to read the inner Track, moves a little outside and then repeats this behaviour in an endless loop. I am very skilled in soldering but a noob in understanding how an IC buffers data.

Is there anything I could check with a Logic Probe or an Oscilloscope ? No problem to swap IC on try and error, but I prefer to find out, why the Unit has that strange behaviour...

[Xenogears]

Update: If I use the Change Disk Option in the Bios-CD-Player and put a Game-Disk inside, the Unit reconizes that and returns to the Super CD-Rom² Start-Screen. Here it idles and tries to read the Data until you reset or turn of... ?!?

[Xenogears]

SOLVED: IC 106 caused the malfunction  . 

I desoldered it. 

Replacement was a Standard SRAM. It works fine now. 

thesteve... you must be a NEC-Cyborg, able to just put your Hand on a PSU and you know, what the Console suffers from. It the Empire had you as an engineer for the dark side, the Rebels never had a chance to blew the Death Star. :-) So thanks god, you are a Jedi-Master! Thank you 

[thesteve]

lol, your welcome
everything i know about the duo was from going through them, finding the issues
seen that ram dead once

[wilykat]

He is like the God.  Present him with a few details, he can tell you right down to which chip or other part to check or replace.

[Xenogears]

Update - if you replace with a Standard S-RAM please let PIN 26 Float. The Sanyo 64K x 8 Chip had a 2nd CE input. I used a Sony CXK58257 - 12L. Here Pin 26 is A13. If the Engine pulls 26 to high/low on this Chip, Video crashes awaful. 

After some testing, this seems to work fine now. 

Here is a link to the Sony IC Datasheet:

http://pdf.datasheetcatalog.com/datasheets/320/199959_DS.pdf

[thesteve]

finding pin compatible 64k8 chips isnt that hard, its the same as the work ram by the card slot