PCEngineFans.com - The PC Engine and TurboGrafx-16 Community Forum
NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: Ninja16608 on March 29, 2014, 02:42:02 PM
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Hi everyone,
I hope I'm in the right area for this.
Anyhow I have a PCE CD Rom unit and the cd unit just died on me #-o I went through a few test to try to see if I could find whats wrong with it. After a few hours of messing around and reconnecting ribbon cables and checking grounds etc. I did a simple screw driver in the door jam and watched. I'm not getting and sled movement nor any disk spin up (probably due to sled not hitting center switch). The gears are original and look to be fine. There is no motor noise at all and no focusing of the laser (bob) the sled just stays at the outer most area of the disk. So my question is where should I start to look. I have read about cap replacement, motor replacement, laser assembly replacement. I am technically inclined but I have never had to mess with a unit like this before and after reading some horror stories on the forums I'm looking to avoid high dollar cost and headache.
Thanks for any info in advanced
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The center of your middle gear had swelled up making it too difficult to move. try moving the gears by hand and see what happens.
If you can get them to move then you can try to drill out the center of the middle gear in order to let it spin freely again.
Do not over grease or lube the gearing because it doesn't help anything.
If your middle gear is beyong repair then I sell a replacement or sorts for $12 shipped.
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Thanks Keith I will give it a shot and let you know how how it turns out.. By the way I hear your one of the guys to see about repairs. If I can not get it to work or find it beyond my scope would you be willing to take a look at it for me?
Thanks again
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Ok just moved the gears by hand, seemed to give a little "pop" and now seem to move freely.....Little lube maybe?
Going to test.........
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SON OF A BI7CH,
After moving the gears by hand I turned on the system (screw drive in slot) and the laser moved. I loaded up a cd and off it went playing like a charm!!!!!!
Keith you are the man!! :clap: :clap: :clap:
Now, how can I keep this from happening again? Is there any solution at all?
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It will most likely be stuck again the next day.
take off the middle gear and drill out the center of it slightly so it won't get stuck anymore.
DO NOT LUBE IT!
I can't tell you how many CD drives I have worked on that have been covered in oil or wd40 which does nothing but make all the pieces of tape inside the drive fall apart.
I'd be happy to work on it for you if you get tired of messing with it.
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Heh, worse thing you can do is mistakenly use WD-40 which is not meant for long-term lubrication. WD-40 is temporary as it evaporates after a day or so. It's meant to free stuck rusted bolts, hinges and useful for temp lubrication if you don't want grease/oil on the surfaces long-term. It will act as a degreaser so spraying it on a lubed gear means that there'll be less grease on it afterwards and then when it evaporates, you have more, not less, friction overall!
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No I would never use WD40 I use that to break lugs on the car or rusted bolts, never on my electronics. I have seen some bad grease jobs too where its just gunked on there, I would think that would make things worse. Seeing as how they are very low RPM gears I would not see the need to lube them, but the shaft that holds the middle gear, would lubing the shaft itself help the spin. The only reason I ask is I dont want to drill it out and make it too big, then it gets sloppy. If drilling is the only way, what size bit would you recommend?
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use a drill bit smaller than the hole and just kind of push the gear around on the drill bit a little bit. it won't take much. you should feel the gear spin freely with hardly any tension.
lubing the said gear won't help much since the hole has swelled and is now too small. however lube would be good to keep the friction on said gear to keep it from breaking.
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Kinda interesting, I never heard about this type of problem, a gear actually swelling a bit and the hole that it spins on becoming smaller.
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The thing that gets me is, the other two gears seem to made from a different material than the middle one. Curious why they would do that, but seeing as how it has lasted better than 20 years with no trouble at all I guess I can't complain too much.
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The thing that gets me is, the other two gears seem to made from a different material than the middle one. Curious why they would do that, but seeing as how it has lasted better than 20 years with no trouble at all I guess I can't complain too much.
The middle gear is the PC Engine CD's achilles heel; at this point almost all of them turned to swiss cheese or don't have much time left.
As for why they would do that, as far as I know it was pretty normal to use different types of plastic for gears, as the lower-quality plastic was likely the only type available or it was just cheaper. Systems with similair problems are the Famicom Disk System with it's fragile drive belt and the US SNES with some of it's exterior yellowing.
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before the gear breaks it typically swells up in the inside. Either that or old gunked up grease has hardened to said gear making the hole smaller. This is why everyone greases them up thinking it will fix the problem in reality just prolonging the inevitable of the gear just getting stuck again in a few days or breaking all together.
If you don't want to mess around with getting a new gear then drilling out the center of the old one you have is your best bet. I have done this many times. Trust me it works. However, I can't say for how long since these gears always fall apart. Usually best to just replace them.
Here is a link to a replacement gear that I sell to forum members.
http://www.pcenginefx.com/forums/index.php?topic=10224.0
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The alternative is to buy 2 replacement wheels with matching gear pitch and glue them together with epoxy. This has worked for me, I can proof. The finer pitch compared to chops gear gave me better results in fine tracking...I noticed a big difference after changing it out.
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Keith is the man, I pulled my CD unit out of storage last year when I bought my house and found it not working. Mailed it off to him and got back a beautifully refurbed drive for what I consider peanuts.
But as was said when I suggested his work on another forum, can you really find a better Turbo authority than Keith Courage himself?
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But as was said when I suggested his work on another forum, can you really find a better Turbo authority than Keith Courage himself?
Well, if you're gonna ask, then there is an answer: thesteve. He's a real, formally trained electrical engineer who, in addition to providing the usual repair/mod services here, has done other wonderful things like designing a cheap YPbPr Component circuit for NEC hardware and making the 3.5" LCD mod possible on Turbo Expresses with $20 Composite-only LCD models found on eBay. But what really separates steve from everybody else is being a real EE and such a fan of NEC systems means that there isn't a problem he couldn't fix, and if not him, if he can't fix it, then nobody here would be able to either.
So, from newly developed mods, to teaching and sharing tech info to interested parties here, being able to diagnose IC chip failure, hell, even save a Turbo Duo with a damaged PCB that was missing a piece of it, etc. there simply is nobody that can compare to the power of steve. ;) He is far too modest and humble to self-promote himself and his talents, so somebody else has to do it for him and make sure he takes his rightful and legendary place in PCEFX history when it comes to modding/repairing NEC hardware!!! :P
One key consideration when choosing a service provider here is how well can they handle the unexpected ?? If they're not a real EE, then odds are less in your favor. Say you send your Turbo Duo off to somebody that only knows how to replace capacitors and in the course of shipping, the CD laser gets damaged or after cap replacement, another issue turns up like IC failure. You will have it shipped back in failure and you'll have to pay shipping again+another repair charge to someone like steve who can handle all possible issues, scenarios, etc. who knows the hardware inside and out, who understands the recently relased NEC tech documentation, etc.
Why take the risk with 2nd best or 3rd best when you know who the best of the best is, someone who can handle all possible problems the FIRST time around ?? When you look it that way, the answer becomes clear when choosing who you're going to ship your precious NEC hardware off to and trust with...
In conclusion, when/if the day comes that my US Turbo Duo no longer functions and I fail in my attempt to repair it myself, I know who I will be shipping it to with 100% confidence and trust. Do you ?? Can you say the same ?? In thesteve we trust. :P
Well, thank you for listening, you may now resume with your regularly scheduled "foruming..."
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Well, if you're gonna ask, then there is an answer: thesteve.
+1 from my experience too.
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back on topic
the center gear is a low density plastic
they used it to reduce noise as it is somewhat rubbery
the issues are the LD plastic tend to be somewhat porous, absorbing hydrocarbons
the HC's cause the plastic to swell and degrade