duo full of problems

[rfernov111]

Hi everyone,

Found this a amazing community a couple of days ago after buying a duo and felt like I could ask for some help here, sorry if its not the correct place

So...I got this duo on ebay in November. The seller claimed it was recapped which led me to believe it was problem free

I went to play red alert (original disk) and I could play almost-normally but I felt that sometimes it took too long to read the disc.. Since I have some experience in electronics + soldering I decided to open it and immediately found the horrors committed to this beautiful system.

Lots of leaking capacitor fluid still on the board....close to the AV connector it was really yellow. Some capacitors soldered to non-working (now floating) pads. IC506 blackish (even the legs). C315 completely dead. Some vias fully black. The person kinda destroyed VR102. The list goes on and on 

I cleaned whatever I could with a cotton swab and Isopropyl alcohol. I redid some soldering and connected the floating pads directly to their correct place by testing continuity where the traces led. Then I went to the CD.

I tried as best as I could to calibrate the pots by looking at the eye pattern following this guide (https://www.retrosix.wiki/laser-tuning-pc-engine-duo). It still not the best. On Rondo of Blood (CDR) sound test the sixth track stops but the disk keeps spinning. If I try to play Book of Ys, when I get to the talking lady on the first dungeon the laser moves totally to the right and gets stuck there (I have to manually force the track with my fingers in order for it to unstuck). If I turn VR103 CW it stops doing that but also stops reading and the pattern becames a fuzzy mess.

Can anyone give me some tips here? I tried the pots, the eye pattern on the scope looks kinda ok but this problem of getting stuck and the music stopping is very confusing (it sounds like a bad cap because it happens after a while?). Also when playing the CD the music is only coming out on the left channel....

All in all this was a bad experience but it is not completely ruined. I can play HuCard games fine and I was able to install a RGB mod. Thanks for any help

[NightWolve]

Yeah... I see the VR102 damage, like someone took pliers and bent 2 ends together... Weird that someone felt the need to tamper with it... Can't imagine they even knew what it's for, what they thought they were gonna accomplish.

Anyway, sounds like there are too many problems and you're gonna have to hire a repair specialist if you wanna save it. Try @Keith Courage.

[rfernov111]

Wish I was in the US to get some professionals to do it :/ I'm in south america
I ended up fixing the audio and the caps (it was mostly leak capacitor on the board + bad traces).

My biggest problem now is the cd :/

EDIT: Captured the problem https://1drv.ms/v/c/4b0117f8503301c7/IQCYNZaGSsuzQrV3zSFFDksLAR8HLqT9rehHggXNk4e36SU?e=oVUlTG

[NightWolve]

Hm, alright, I'll forward that to @thesteve (a PCE EE) and Keith Courage.

[thesteve]

Vr102 may still work
Set your scope sync to left and the pattern looks ok
Im thinking you vr102 is all the way right and should be about center
The getting stuck issue if I understand what you're talking about could be a bad tracking motor (seen it a few times)

[thesteve]

Also note the pot under the 2 caps (vr103?)
It's all the way right and shouldn't be

[thesteve]

Note this is a standard Sony cd chip set
Any cd player using this chip set should have the same adjustment procedure

[rfernov111]

I was able to mess with the unit today again and after messing with VR103 (turning it more CCW) Rondo now plays the music non stop. The Ys issue still persists (I'm going to trust Steve and maybe try to find a replacement motor). VR102 is functional but looks horrible. Anyway, work in progress but apparently is progressing well. Thank you for your input Steve and thanks NIghtWolve for summoning him I'll come back soon-ish with more details/progress report.

In a side question: Steve, would you know how the Huc6280 digital DACs work? I'm under the impression they receive the 3 bits for each color and just scale them to send the signal but I'm not sure. I'm asking because I'm trying to make a RGB->YUV color lut on the OSSC (I kinda got it working but the image is kinda yellowish and I'm wondering if its the signal getting scrambled somewhere due to noise or maybe I'm misunderstanding the DACs). Thanks once again

[thesteve]

6280 doesn't handle image at all
The picture is rendered in the 6270 and scaled and colored in the 6260
6260 does have RGBSHV available at the chip

[rfernov111]

Doh! You right, stupid typo. I meant the 6260 and I got the idea from the furrtek reversed lut yuv table (from https://www.furrtek.org/?a=pceyuv)

[NightWolve]

My biggest problem now is the cd :/
EDIT: Captured the problem https://1drv.ms/v/c/4b0117f8503301c7/IQCYNZaGSsuzQrV3zSFFDksLAR8HLqT9rehHggXNk4e36SU?e=oVUlTG

BTW, this is one of the few times I think I can contribute a solution to these sorts of problems: The grease on the laser slider pole is 33+ years old, well, what's left of it; it's mostly gone, dried up... You need to thoroughly clean up the pole/all moving parts with alcohol or something stronger, then apply fresh new white lithium grease!

When my US Turbo Duo started doing this - cutting off a BGM Redbook CDDA track halfway - I'd apply petroleum jelly which is all I had at the time, and it'd work a little longer. Not an ideal lubricant, but it worked. Anyway, it *might* be as simple as that for this, but obviously you had worse problems with that unit!

Protip: It helps if you unmount/free the motor & sprockets so you can freely slide the laser back'n'forth once you start applying new grease, then you can fully cover/spread it all around far better! But those screws are glued/tight, might be hard to free them, and something could break. Beware. But yes, this CDDA cutoff problem happens because the laser unit has lost its agility moving across the pole without any grease! The friction is much higher! So try this before replacing the whole laser/motor assembly.

[rfernov111]

Awesome, thanks for the tip! Yesterday I noticed that the cd laser pot screw also doesn´t turn (any way) so I'm assuming the person that touched this also glued it -_-

[thesteve]

The pot on the laser was glued at factory
I generally break them loose