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[Console Repair/Mod Center / Dead CD Spindle Motor? How to Replace?]

I have acquired a recapped PC Engine Duo, but when I got it the CD spindle did not spin up sufficiently to make the disk spin and nothing could be read.  I could see the laser head moving up and down, so I thought that the motors may be bad.  I bought a new disk laser assembly : https://www.ebay.com/itm/182710804499 to replace the old one. 



When I got the new assembly today, I found two problems with it.  First, the wiring was different but the same points are present.  The second issue is much more of a problem.  Simply put, the spindle platter on which the disc sits is below the laser head assembly.  If you put a disc on the platter, half of the disc will rest on the laser assembly plastic.  I don't know how this was supposed to work with anything, but I do notice that there is a silver shaft that has room to move the platter upward on this assembly whereas on the old assembly the shaft was about as high as it could get.

I really believe that the disc shaft motor on my old assembly is not working anymore.  I applied ~3v to it and the spindle did not move where it did move on my new assembly.  The disc spindle motor and drive sled motor are powered off the came cable and BA6290A, and the drive sled works fine.  I found out how to adjust the height of the platter relative to the shaft, so I should know more once I replace the power cable from the assembly.

[Console Repair/Mod Center / PC Engine Duo Repair and Mod Advice]

A friend of mine let me borrow his PC Engine Duo he received from an ebay seller from Japan called doujindance.  doujindance had replaced many of the surface mount capacitors and had installed an RGB mod.  He replaced the 5-pin DIN AV port with an 8-pin DIN port for the RGB lines.  There is a small board connected on one end to the DIN and on the other end to what I presume are the appropriate lines from the HuC6260A on the underside of the PCB.  I also understand that the CD-ROM laser assembly has been replaced.

Issue One : Freezes when playing ADPCM from CD

When I received it, I was able to test the HuCard slot with a Turbo EverDrive, and that works just fine.  However, I have been having serious problems with CD games crashing.  At first, I was only using CD-R backups, typically with high quality Taiyo Yuden CD-Rs burnt at 16-24x.  Many games would load correctly, but several would crash at certain identifiable points :

Ys Book I and II - Start a new game, game will freeze at the screen "In the Beginning"

Ys III - Game froze during the scene in beginning where Dogi speaks to the girl.

Ys IV - Game froze after Dogi speaks for the first time

Dracula X - Game freezes at loading FMV cutscenes.

All these instances have something in common, at these points the game will need to stream digitized ADPCM speech or sound effects from the CD.  I understand that the chip responsible for streaming ADPCM is the M5205 OKI ADPCM Speech Integrated Circuit.  At these points, I can reliably reproduce the crash.  Trying to narrow down the causes, I tried a genuine Ys Book I and II CD and it crashed at the same point.  These games will work if these areas are avoided (sometimes not possible) and CD audio will play fine.  I tried fiddling with the laser adjustment pots to no avail.   

There are other instances in some of these games where ADPCM is used and I never hear the speech or sound effect, but the game will not freeze.  Once or twice, ADPCM did work and Dracula X and Ys Book I and II did not crash at these points or any other point and played all speech and sound effects back correctly.  I could not figure out why the ADPCM would occasionally work but usually fail.  I suspect that this chip is failing and needs replacement, console5 offers them for a reasonable price.  Alternatively, I may need to replace the rest of the surface mount caps that have not been previously replaced.  Any advice would be appreciated. 

Issue Two : Jailbars in RGB Output

When I looked at the PC Engine's Duo's RGB output through a Framemeister, it generally looked great, but on some games, jailbars were quite noticeable.  These jailbars are not present on the native composite video output.  In this post, you can see pictures taken of my own screen :

http://nerdlypleasures.blogspot.com/2015/05/fun-with-framemeister.html

In the beginning Bonk's Adventure, they are very noticeable, with other games their visibility varies.  It is something that once it has been seen, it just cannot be unseen. 

Now the mod that doujindance installed looks to be using a tiny amplifier chip and some passive components.  It does not bring composite sync to the AV connector, there just aren't enough pins on the connector.  Sync comes from the composite video sync.  Do I need a different mod or do I need to bring composite sync to the Framemeister?