pcengine Duo broken pot on laser pickup

[xnopasaranx]

Hello people! I didn't quite know what to search for but have tried and found nothing helpful.

I just bought a duo and hucards run great. picture and sound is stunning. the cd drive however is busted, as the Potentiometer on the laser pickup is completely crumbled.

is this replaceable or should i just buy a new hop-m3 instead? what kind of pot would i need?

cheers!

[thesteve]

the pot can be replaced, but should likely be replaced as an assembly (HOP-M3)
its a 2.2K pot, standard 3 pin

[xnopasaranx]

ok, i am going to try replacing the part first, not much i can screw up  worse and i can still order a new assembly i guess if it won't work. thanks for the quick reply!

i am really excited to have finally gotten my hands on a duo. they are very hard to come by in europe. had a turbo grafx gt before but only one game. it would be great to get the cdrom working again. i'll post about my progress.

[Drakon]

Yeah trimmer resistors are easy swaps.

[xnopasaranx]

Now that I know that it might be an easy fix it's driving me nuts^^. Didn't have the time to go and pick up the replacement pot because of work. And now that I can actually go home early I am super pissed as today I would have had enough free time to actually solder and tweak. Crap.

Oh well, just me being impatient. Also: replacement pot. Lol.

[xnopasaranx]

Hello again!
I managed to replace the pot and tried tweaking the silver pots a little. No success as of yet. I tried the measurements from the laser swap guide but to no avail.

I can get an audio cd to spin continuously and I can also get the laser moving a little bit. Sometimes there will be a bit of a buzzing sound from the headphone port but it doesn't seem to be any kind of actual data, probably just noise and static. I tweaked vr102 and 104 until there was no screaching or whining anymore and it sounded like a cdrom is supposed to sound (in my opinion).

Any tips? What about the pot on the laser assembly? Any value I could try setting it to? I haven't found any measurements regarding that part, only people saying that it's best to keep your hand off because fiddling with it might burn out the laser. Since I had to replace it though, some pointers would be extremely helpful. I had to settle for a 2.5k pot btw. They didn't have 2.2k for some reason.

Thanks a lot for the help guys! I really hope someone can help me with this.

[xnopasaranx]

Hey quick update! I finally got a new laser-pickup and replaced the one with the broken pot. I guess the laser was burned out from the beginning. Now my pce-duo is finally reading discs! Even cd-rs. I still have to replace a couple of caps since I am getting cd-audio at a ridiculously low level from the headphone out only.

Anyway, thanks for your help! Lotsa very helpful topics on these boards, couldn't have done it otherwise. Cheers!