Author Topic: PC Engine Super CDROM2 trim pot help  (Read 405 times)

joerazzzz

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PC Engine Super CDROM2 trim pot help
« on: June 01, 2020, 08:11:49 PM »
Hello all!

I joined just for this thread. Being that these systems are becoming a dark art and the information is scatter through the interweb I figured I'd just stop the long nights of searching and just ask for help here.

I have a Super CD that worked fine but it had no audio at all. I assumed it was the caps and started to work. I found many bad caps so I replaced every single one. From what I read a full cap replacement would require a recalibration of the laser to work correctly. Using the 10-15 sources of information I could find roughly talking about the process I was able to get the system to read a CD-R directory but it could never find a track or play anything.I found 2 things, First was the CD gearing was stripped and second I tested each trimmer pot (marked original positions prior to any play) and I found that 3 of the 5 had dead spots in them going to 0 ohms or OL. So I figured I'd replace all of these too. With new pots in I was able to get the system to read the directory again but it still will not read any tracks but the CD will spin until I release the lid switch. I tested these pots and they claim to be 20K but I can not read better than 17K so I ordered exact replacements that are currently shipping. All of this frustration I figured I would play a Hue card and I found out that going through the CD-ROM I still do not have any sound.... WTF! Sound is fine through the Core II but this CD-ROM is about to get the old field goal kick.

So my questions I hope you beautiful people can help me with:
1. Where is my sound? I did a full cap replacement and still no sound, what should I look at or if you could provide a circuit diagram I could trace out??? Please any help?

2: What am I missing in the trimmer pot setting? Are there any good reference positions / readings I should set the pots to and tweak from there? Would you think the laser is bad if I can read the directory? I have an O-scope coming this week and I can do a proper calibration but I still need to know what test points and to what parameters I am calibrating to. :bonkthis:


Please help me... I have beer in trade. :pray: :pray: :pray: