In-game symptoms of laser or bad cap problems?

[md5fungi]

Hey everyone - there's a lot of terrific information on this forum (and on the greater internet) about how to go about adjusting pots for your system's laser, replacing caps, etc.

However, I'm failing to find a lot of clear examples of in-game symptoms of these problems, specifically the symptoms I'm seeing.

I have a PC-Engine Duo RX and all my HuCards work flawlessly without issue, and most of my CDs do. However, I have three games that seem to stop playing music at certain points (but the sound effects continue). Burning these games has no effect - the music drops out unexpectedly and doesn't come back. There are no strange audio artifacts... The music just stops.

Is this related to bad caps or does my laser pot need an adjustment? Are there predictable in-game symptoms of these sorts of issues?

I also attempted to back up games on Taiyo Yuden CD-Rs, but I can't seem to play them from this media. Memorex CD-Rs work, though...

[md5fungi]

To provide a little detail of what I do know/suspect, I would think that one or more bad caps could be causing the audio cut-out, though as I stated, no noisy artifacts.

As far as the laser pots, I would think that maybe I would have to adjust vr405 since most everything plays flawlessly, but not everything?

[Keith Courage]

Probably just lens adjustment+re-greasing of the lens rails needed. I'd try just cleaning and re-greasing the lens rails first. I rarely come across a DUO-R or RX that needs new caps.

[md5fungi]

Oh cool - I'll give that a shot. Thanks for the advice!

[NightWolve]

I have a PC-Engine Duo RX and all my HuCards work flawlessly without issue, and most of my CDs do. However, I have three games that seem to stop playing music at certain points (but the sound effects continue). Burning these games has no effect - the music drops out unexpectedly and doesn't come back. There are no strange audio artifacts... The music just stops.

You're very much in luck based on what you described, you should be able to fix this yourself!

Good thing about that is you avoid risk to the laser assembly which is fragile and can be damaged during shipping back'n'forth between you and somebody else (besides saving yourself the cost for repair/shipping).

As Keith mentioned, this is a lube problem, and I already did a write-up years ago to help:

"Re: REPAIR GUIDE - TG-CD: Grease is dried up. Symptoms and Solution."
https://www.pcengine-fx.com/forums/index.php?topic=7012.msg296648#msg296648

But quick recap: The laser's slider pole has ~25 year old dried-up grease at this point (as old as the console), the laser unit has lost agility as a result, so a good cleaning of the old grease with say alcohol, and application of new white lithium grease will do the trick!

I recommend freeing the slide motor (2 glued screws, it's tough) if you can which will let you move the whole laser unit freely, and also to clean/lubricate all sprockets, not just the pole, etc. In short, fresh grease needs to go everywhere there's old grease!

I assume you know you also need a 4.5mm game security bit which you can easily find on eBay to be able to open NEC consoles. The white lithium grease you can purchase at most any hardware store.



Funny thing, I used petroleum jelly when I had this audio cut off problem, it would work normally again for a year or two, before drying up and leading to the same problem. That was the poor man's way using something already in the home, but obviously not appropriate for a long-term solution. Somebody here once talked about a better grease, Molykote, what's used for joysticks, but I dunno if you wanna experiment just yet.

P. S.

Do *not* touch any of the 3 CD potentiometers, this should just strictly be a grease/lubrication problem.

[md5fungi]

Awesome! The explanation in your write-up makes sense and I'm glad to see that it matches my symptoms exactly.

I appreciate all the kind help! Will get my system greased up so I can commence the gaming!