Turbo Duo Not booting games

[Ryo Seadas]

Hi!
I have a problem with my PCE Turbo duo.
It has been recapped 5 years ago, and it worked perfectly.
Now I tried it again recently, and there's a problem: It can play cards and audio CDs (original and backups) perfectly, but I can't boot any game!
I think the game is recognized (if I am in the audio CD player, It comes back to the initial screen with the "press Run" prompt), It spins forever and stays stuck in the "please wait" screen
What I tried so far:

1) new Power supply (works perfectly with another duo)
2) full Optical Pickup assembly swap with another working (except sound) duo (and on the other this assembly works)
3) messed with the 5 potentiometers

Any suggestions? Thank you!

[Keith Courage]

I've seen this happen before and it's usually caused by a bad trace or via connection on the board. Unfortunately I can't point you as to which one since I don't remember which connection I had to repair to fix this before.

I would hold the board up to a light and see if you notice any Via holes that are blocked(can't see light through them). This is an indication of old cap fluid that had leaked prior to the recap. The Vias and traces to check would be around the 3 Larger chips just below the CD drive on the top part of the board.

[Ryo Seadas]

Thank you for your suggestion.
So far, the traces and the via holes seem good.
I will continue to try and test

[NewPCEngineFanatic]

I have had this happen on a few of my systems.

The first thing you should try is isopropryl alcohol(rubbing alcohol).

Unplug your console from all power, then take a cotton swab and not only rub the lens, but use a nice thick drip so that it runs to the bottom side of the lens and dissolves the dirt on the bottom side of the lens, which is hard to get to without breaking the assembly.

Since you havent used it in a while, it could just be a little dirt. The lasers on these are very weak compared to our modern lasers. They wont see easily through dirt.

If this doesn't work, your laser could be burning out. Most people say you should buff up the laser voltage with the pots on the assembly, but I highly recommend just buying a new laser, as it's only ~$15-20 and will have to be done eventually even if it isn't the cause(which it probably is).

[Ryo Seadas]

I have had this happen on a few of my systems.

The first thing you should try is isopropryl alcohol(rubbing alcohol).

Unplug your console from all power, then take a cotton swab and not only rub the lens, but use a nice thick drip so that it runs to the bottom side of the lens and dissolves the dirt on the bottom side of the lens, which is hard to get to without breaking the assembly.

Since you havent used it in a while, it could just be a little dirt. The lasers on these are very weak compared to our modern lasers. They wont see easily through dirt.

If this doesn't work, your laser could be burning out. Most people say you should buff up the laser voltage with the pots on the assembly, but I highly recommend just buying a new laser, as it's only ~$15-20 and will have to be done eventually even if it isn't the cause(which it probably is).

Thank you for your reply, but I've already swapped the entire laser assembly from another fully working duo. In the other unit, the assembly works (and still have the same problem in this unit with the "new" assembly from the other one)

[NewPCEngineFanatic]

I see... that actually seems like it could be a pot in that case, but weird that it would be any different even though you havent touched it...

They should be the last things you try cuz you can really get them wacked out. Have you scanned the board closely to see if there is corrosion on capacitor areas, like nearby components? I just fixed a regular Duo that had leaked into a chip, badly corroding the legs on it. I had to toothbrush it down and touch it up with the iron.

[Ryo Seadas]

Still no luck... I've removed all the three cdrom ICs and cleaned underneath. Now I have a little problem: The traces and pads for capacitor C122 (the one on the bottom right) are gone forever. I don't think there are schematics, where the positive and negative legs are supposed to be connected? Thank you

[Keith Courage]

The traces go through the Small via holes for that Capacitor. One just below it and the other up and to the left a little. Use a capacitor lead through the bottom via hole for repair and then a very small wire for the upper one since the hole is much smaller.

[Ryo Seadas]

The traces go through the Small via holes for that Capacitor. One just below it and the other up and to the left a little. Use a capacitor lead through the bottom via hole for repair and then a very small wire for the upper one since the hole is much smaller.

Thank you very much for your reply. The Via hole connected to the positive lead of the capacitor seems to be connected to the circled area on the bottom of the board. The other via holes on the bottom near the point doesn't seem to be connected to anything, and the resistor R137 is missing. So it looks like the positive lead of the capacitor is connected to a dead end. Am I missing something? R137 is supposed to be present? Thank you again.

[Keith Courage]

That resistor is empty on most duos. It's weird that it almost looks like one was removed though. Did you solder on both sides of pads?

[GTSS]

Sorry to ressurect this topic but the info may come handy to someone that ripped the pads of the C122 cap, I know it happened to me....

So the possitive of this cap goes as correctly indicated above in the picture. The negative goes (through the via) to the one side of R115 (back of the board). See the soldering on the R115 trace?

My DUO has the R137 but on all I've seen on the web its missing.

UPDATE
I redid the capacitor today and installed a tantalum instead (100uf 16V) of an electrolytic for the main reason that it can be glued into place with a small drop of a two part epoxy glue. The positive soldering point has been updated too for the main reason that running a cable from one side of the board to the other is not cosmeticly pleasing.