PC Engine Duo

[Tarma]

Got an issue with the CD Rom on a PCE Duo, and I'm hoping someone here might be able to point me toward a fix...

The CD Rom drive won't spin up properly to recognise a disc. When you hit run it starts to spin (slowly) and then gives up after a few seconds saying it cannot detect a disc.

Ok, so ALL caps on the system have been replaced.
That's done nothing to improve the issue.

The motor for the assembly has been tested and is fine - it's not the motor.

The laser lens has been swapped out for a brand new one - same issue.

I've exchanged the entire CD-Rom assembly from a known working Duo to this faulty unit and the donor CD-Rom then has the same issue as the original.

So, something tells me it's something on the motherboard, but what I don't know!

Anybody out there come across this before? Any suggestions for things I should be testing / looking to replace?

[kamiboy]

Double check your recap job for shorts, broken traces due to leaking caps etc. Especially the caps around the CD assembly.

[Austin]

There are multiple pots on the mainboard that may need to be adjusted.

[Deubeul]

Check VR101 to 105.

VR101 = E/F balance, pin 13 of U101
VR102 = Focus Offset, pin 18 of U101
VR103 = Track Gain (Track error level), pin 45 of U102
VR104 = Focus Gain, pin 48 of U102
VR105 = VCO, pin 30 of U102

[kamiboy]

Note the placement of each pot before messing with them. It’s a nightmare to readjust the pots if they are turned out of spec.

[Tarma]

Thank you so much for the suggestions so far, I will follow them up and get back to you.

I have already checked for trace damage but haven't been able to find anything... I was hoping it would be something to do with the actual CD-ROM unit, but when I swapped it (completely) for a known working unit, and the problem was the same, I knew it wasn't going to be straight forward!

[Deubeul]

Here's a good read:

https://www.pcenginefans.com/forum/inde ... ic=20542.0

The guide which explains how to adjust the pots "by ear" is very usefull.

[Tarma]

Here's a good read:

https://www.pcenginefans.com/forum/inde ... ic=20542.0

The guide which explains how to adjust the pots "by ear" is very usefull.

Awesome, this could be really, really useful, thank you

[jd213]

I also need to adjust my Turbo Duo one of these days, had it re-capped and adjusted by a pretty well-respected modder a couple years ago, but redbook audio now stops in the middle of a track.

Any idea which pot should be adjusted for such a problem?

[Bratwurst]

I also need to adjust my Turbo Duo one of these days, had it re-capped and adjusted by a pretty well-respected modder a couple years ago, but redbook audio now stops in the middle of a track.

Any idea which pot should be adjusted for such a problem?

That could be one of the 4558 opamps failing. I fixed a Duo that would play music fine on initial load but then it would cease after a few minutes. There's more than one of these chips on the board, look at IC203 in particular and see if the text on the chip surface looks faded compared to the others, or if any other instance of this chip elsewhere looks 'cooked.' I believe there's one located underneath the power conditioning area with all the radial caps and volt regulator that I had to replace as well.

[jd213]

I also need to adjust my Turbo Duo one of these days, had it re-capped and adjusted by a pretty well-respected modder a couple years ago, but redbook audio now stops in the middle of a track.

Any idea which pot should be adjusted for such a problem?

That could be one of the 4558 opamps failing. I fixed a Duo that would play music fine on initial load but then it would cease after a few minutes. There's more than one of these chips on the board, look at IC203 in particular and see if the text on the chip surface looks faded compared to the others, or if any other instance of this chip elsewhere looks 'cooked.' I believe there's one located underneath the power conditioning area with all the radial caps and volt regulator that I had to replace as well.

Thanks, will try opening it up again soon.

[jd213]

Whats the best way to remove these opamps? Tried replacing 4 of them on a yellowed (purple plastic is now brown) PCE Duo I got fairly cheap.

Had a bit of trouble getting them off, it seems they're either glued, or leaked electrolytic fluid was holding them down, so I ended up using too much hot air in one place, causing something under the bottom layer to pop and make the board swell a bit. Also melted the base of one of the SMD capacitors on the other side, which was a bit difficult to clean up but I eventually got it off by gently brushing with a fiberglass pen.

Removed the next opamp by just individually heating and lifting each leg. Thankfully everything seems to work fine after I got the board cleaned and all the capacitors replaced.

[Bratwurst]

Clip the legs of the op-amps at the very top with flush cutters, you can then gently twist/rock the black chip package off of the PCB with small pliers or similar to break the weak glue holding it to the board. Afterwards heat the legs individually with your iron to remove with tweezers (often they just cling to the iron tip and you can brush them off onto a damp sponge or whatever.)

[jd213]

Ah, sounds good, thanks again. I'll probably have to get some finer cutters, mine don't quite fit inbetween the legs.