REPAIR GUIDE - TurboDuo/PC Engine Duo: Total capacitor replacement chart

[Echoes]

Does anyone have the values for the capacitor that should be in the spot marked C001? It seems to be missing on the Duo I picked up and that one doesn’t seem to be listed on most charts I can find.

[Keith Courage]

Is this for a pc engine duo? There is one spot on the board that is missing cap from the factory and is supposed to be like that.

Post a picture of the spot on the board here and I'll let you know.

[Echoes]

Is this for a pc engine duo? There is one spot on the board that is missing cap from the factory and is supposed to be like that.

Post a picture of the spot on the board here and I'll let you know.

It's a US Turbo Duo, the spot is the white circle right there by the corner of the drive.

https://ibb.co/jVvmMrw

[Keith Courage]

Oh, that cap isn't important at all. Some systems don't even have one there leaving the solder points empty. I'll check what the rating on the cap when I have another DUO opened up. I know it's a ceramic cap but forgot the value.

[demianph]

Is this for a pc engine duo? There is one spot on the board that is missing cap from the factory and is supposed to be like that.

Post a picture of the spot on the board here and I'll let you know.

It's a US Turbo Duo, the spot is the white circle right there by the corner of the drive.

https://ibb.co/jVvmMrw

Sorry for the necro but so the information is available I am replying.
Have mine open to re-cap (I found 5 definitely leaked surface mount caps).

Mine was manufactured October 1992 and has the cap.
Markings are:
   B
103K
symbol that looks like a M inside a C (manufacturer mark maybe) then 03

Internets say this is 10000pF (.01uF) with a +/- 10% tolerance and voltage is 50/100 volts (the underline). I think the B is the temperature code or flammability rating which it appears no one uses anymore.

[qingtongyoushou]

I am helping my friend fix his PC-Engine and this is very useful information

[game freak99]

I got a PC engine Duo that still has sound issues despite having what looks like a new set of caps. Do any of them look like the last owner missed them?

https://imgur.com/a/c7tbzPh

[Keith Courage]

Just changing out the capacitors is only part of the work. Lots of times there are damaged traces and or shorts in via holes that need to be repaired during a capacitor change. This is most likely the problem as to why you are still having sound issues.

So the connections for the capacitors need to be checked to make sure the traces all have continuity and that the via holes have the correct continuity through them as well.

there is also the possibility of some old capacitor fluid being underneath one or more of the op amps or even possibly some of the resistors on the board.

[game freak99]

I just got a set of opamps in the mail today so I'm going to replace at least the one closest to the power regulators.

On the subject of the power regulators I'm reading 12v from the leg that feeds the opamps and supposedly it should be  only 8v. Then the transistor that is between the power regulator and the opamps is only outputting 1.6 volts. Do any of those parts sound like a likely culprit to you?

[Keith Courage]

One pin should be around 12-13v and another 5v.

If the voltage regulators weren't putting out the correct voltage, either card games or CDs wouldn't be working at all. so the voltage regulators are probably fine.

There's probably a bad trace,shorted via hole, or old capleakage under an op amp somewhere in the area above the heat sinks.

[game freak99]

That makes sense. Could there be something wrong with q304 making it only output 1.6 volts instead of 7-8 like it's supposed to? Or maybe something upstream from pin 1?

Also, when I first tested the unit there was extremely quiet sound, but after I washed the board with 99% isopropanol (lots of brown gunk on my qtips!) there was none. Could I have loosed up some capacitor gunk from the board and ended up getting it into worse places?

Thanks for your advice!

[djbunyan]

Hello! Is anyone in here willing and able to help me fix a PCEngine Duo?