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

Xenogears · 04/06/2016, 04:21 PM

Hello PC-Engine Fans,

I have a strange issue with a PC-Engine DUO. It´s recapped, the Laser is tested in a different unit and the Pots work fine. If I insert a CD-Rom, the DUO does not recognize it. Does anyone know, how the NEC-Microcontroller checks, if there is a Data or Audio Disk ?

thesteve · 04/07/2016, 02:17 AM

well the system reads the TOC
then if the TOC shows data on track2 it starts buffering from track2
if it reads all as audio it has a problem in how TOC is read, but if it just doesnt load on game discs then it recognizes it but has issues buffering it

schweaty · 04/09/2016, 05:26 AM

You know the pots on the duo aren't on the laser, right (there is 1, but that's not the pot that needs adjustment)? The pots can be out of adjustment and the laser can be fine at the same time.

Xenogears · 04/10/2016, 04:25 AM

Schweaty, thanks for the idea but the VR 101 - 105 are already adjusted. I guess the thoughts of thesteve are the ones to follow and investigate. The DUO does not read all as audio if I am right, it should make data hearable. It just reads Audio-Tracks but no Data. If I insert a Game Disk, the disk is recodnized, spins and than, after the typically loading-sound it "idles" at the "just a moment" screen forever. I mean it does not interrupt with the "Please set Disk" message...

thesteve · 04/11/2016, 01:45 AM

and i have seen that a few times
start with audio CD
using the bios CD player watch the time/track and level displays as they are data read off cd
also do direct track seeks, and confirm it selects the correct track
selecting incorrect tracks is likely a trace between the 3 QFP closest to the front edge
incorrect displayed disc info is likely a trace between the CXD and IC501
no disc info is likely a dead CXD or IC501

Xenogears · 04/12/2016, 06:37 PM

I used an Audio-Disk that has 12 Titels. It´s read, shows the right Disk Info and plays Titles forwards and backwards. And also directly plays, if I select one by menue. I then changed the Audio-Disk to be certain - also working with a 21 Track Disk and a - The Lord of the Rings Audio-Book with 9 Tracks. Fine so far.

But it does not show the Disk Data (Time/Track) and random and seldom, "the Lady" does not recognize correct Tracks of the inserted CD-Audio. I really tested a lot of times - e.g. if I put in the 12 Track Disk, the Duo startet with Track 5 and denied to jump to the lower tracks by using "<<" or direct select.

After Resetting the Unit by Run+Select everthing seemed fine again...

thesteve · 04/12/2016, 11:11 PM

refusing to read lower tracks could be a lens issue (uncommon)
if it gets any noise while playing audio, it wont read data

smups · 04/13/2016, 02:12 PM

Could you help me?
I have a duo that plays music cd's fine but I can't get it to load a game.
I have recapped the board, raised the spindle and fitted a new lid switch.
I've tried three lasers but I get the same results with all of them.
The board was very clean with only a couple of leaking caps and all the pads seem to have cleaned up well.
Do you think this May be the cxd chip or have I missed a more obvious fault?
When playing music it plays the last song all the way to the end and if I choose the random track feature it finds the tracks with no problems.
I'm not sure what the display is supposed to show but I can see the track number, the length of the song or album, I can switch it to time remaining and the L/R stereo lines look like they move with the music.
Hope this is something you have come across before?

thesteve · 04/13/2016, 04:15 PM

well thats a tough one, it sounds like the cd system is working
whats it do with a game

smups · 04/14/2016, 02:34 AM

When I try a game it will start spinning the disc but then it stays on the please wait screen.
The laser moves, I assume to track 2, then returns to the centre of the disc and keeps doing that.
I some times get the ''load error "message.
I'm trying genuine games that I know work fine, I have tried using my arcade system card but the same thing happens.
Hope this helps?
Will adjusting a specific pot make a difference?

thesteve · 04/14/2016, 03:46 PM

i dont expect an adjustment to help
its getting no data back from the cd to the system
if you open the lid while its trying to load what happens?

smups · 04/14/2016, 05:12 PM

I get the "load error" message.

thesteve · 04/15/2016, 03:01 PM

ok you have an issue with IC105, IC501, IC106 or the connections between
any or all

smups · 04/16/2016, 02:32 AM

Are there any checks I can do on the pins, to see which chip it might be?
I've had a torch shining through the board but I can't see any damaged traces.
The only chip I could attempt is the 106, the other two I would probably kill the board trying to replace.

Vimtoman · 04/16/2016, 03:48 AM

Smups get yourself some isopropyl alcohol a new toothbrush and clean around those IC's and around the CD circuit area.

Below are my Pot settings.
This unit had to be cleaned twice due to it not reading correctly.

smups · 04/16/2016, 09:51 AM

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 · 04/16/2016, 12:07 PM

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 · 04/16/2016, 01:49 PM

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 · 04/23/2016, 09:15 AM

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 · 04/23/2016, 08:12 PM

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 · 04/23/2016, 09:03 PM

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 · 04/24/2016, 04:10 AM

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

wilykat · 04/24/2016, 07:09 PM

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 · 05/11/2016, 07:01 AM

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 · 05/12/2016, 01:42 PM

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