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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: soop on June 05, 2011, 03:58:08 AM
Title: My continuing CDROM2 problems
Post by: soop on June 05, 2011, 03:58:08 AM
I filmed a video. Although the sound didn't come out, it should give an indication of what's wrong.
The disc never spins apart from the occasional shunt, and this is after I replaced the laser. Does this point to something in particular?
Title: Re: My continuing CDROM2 problems
Post by: BlueBMW on June 05, 2011, 04:13:38 AM
Typically when I see them just kind of flick the disc but never really spin it up, its usually an adjustment issue. I'll shoot you a PM with some more info.
Title: Re: My continuing CDROM2 problems
Post by: thesteve on June 05, 2011, 11:32:03 AM
if the spindle is pushed down it will have problems focusing.
Title: Re: My continuing CDROM2 problems
Post by: soop on June 05, 2011, 10:44:43 PM
if the spindle is pushed down it will have problems focusing.
Ah, I forgot to add here - after I adjusted the potentiometers according to the diagram Blue kindly provided, the drive will now light up in PC mode and never switch off. So it looks like it's getting somewhere.
I see - Might I have screwed the cover plate on too tight? I think that's the only way it could be pushed down more than necessary. Although it is actually missing one of the 2 screws. Also, the I can spin the CD ok with my finger, and it won't stop immediately after I close the lid
Title: Re: My continuing CDROM2 problems
Post by: soop on June 19, 2011, 02:50:50 AM
Bumpety bump!
Right, while ago, I messed around with the potentiometers, and I managed to get the drive to spin up for about 5-10 seconds or so. Spins up really fast (in PC and Audio modes), but then cuts out.
Thought I was getting somewhere, but all this week, I've only managed to make everything worse, and then today gotten back to that state.
the pots are being modified by pure guesswork (rather than specific readings), but even so... anyone knows why it won't load? (It never gets past the Super CD screen)
Title: Re: My continuing CDROM2 problems
Post by: BlueBMW on June 19, 2011, 05:05:52 AM
You say it was spinning really fast, like it was about to take off and fly kind of fast?
Title: Re: My continuing CDROM2 problems
Post by: soop on June 19, 2011, 08:54:50 AM
Not quite, not as fast as a modern cd drive, but faster than before. How come?
Just checked; roughly 6 revs per second, 360ish per minute.
Title: Re: My continuing CDROM2 problems
Post by: thesteve on June 19, 2011, 11:16:45 AM
if the disk is spinning too fast it means its not tracking/reading. the speed is controlled be a data buffer. when the buffer is low it spins faster to read faster
Title: Re: My continuing CDROM2 problems
Post by: soop on June 19, 2011, 10:18:30 PM
if the disk is spinning too fast it means its not tracking/reading. the speed is controlled be a data buffer. when the buffer is low it spins faster to read faster
I don't think it's spinning obscenely fast... Blue said in a PM that it might not be finding the table of contents, but I can't find any info on that. Where's the buffer? I have 2 different Super CD cards (though I can't actually test them, since the only other CD drive I have is a Super CD ROM) and the same thing happens with both. I could also try a different core unit, but this one plays games fine, so I doubt it's that.
Title: Re: My continuing CDROM2 problems
Post by: incrediblehark on June 20, 2011, 01:36:57 AM
its probably too late for this, since you most likely tweaked all of the pots, but I found that only adjusting VR101 had the most success for me in getting my cdrom2 to work, i think i adjusted vr103 as well, but it was 101 that seemed to have the most impact on getting my discs to play.
Title: Re: My continuing CDROM2 problems
Post by: soop on June 20, 2011, 03:12:21 AM
its probably too late for this, since you most likely tweaked all of the pots, but I found that only adjusting VR101 had the most success for me in getting my cdrom2 to work, i think i adjusted vr103 as well, but it was 101 that seemed to have the most impact on getting my discs to play.
I don't know which is which off the top of my head, but the leftmost (the one on it's own) has the greatest to do with the disc spinning up or not. Then the two white ones (right-most) seem to have the most to do with the laser focus. But this is all conjecture really on my part.
Title: Re: My continuing CDROM2 problems
Post by: thesteve on June 20, 2011, 07:50:53 AM
the data buffer is in the drive itself. if its spinning up its finding the TOC. sequence 1 lens bobs up and down looking for its reflection. 2 reflection seen, lens resets to center of disk and disk spins to read TOC. 3 system reads TOC and tells drive which track to read. 4 lens moves from center towered edge counting tracks. 5 track found, data reading. 6 spindle speed adjusted as needed to keep data buffer memory full.
Title: Re: My continuing CDROM2 problems
Post by: soop on June 20, 2011, 08:09:45 AM
I have managed to make it do this (interestingly, it likes doing it with music cds) but I think buffering is not the problem
I think the problem is finding the toc. It never goes above 0 on a music cd.
Title: Re: My continuing CDROM2 problems
Post by: thesteve on June 20, 2011, 10:09:50 AM
the TOC is what determines if its a music cd. i suspect its getting a partial read of the TOC
Title: Re: My continuing CDROM2 problems
Post by: Charlie on June 20, 2011, 11:23:02 AM
Got a VOM? Start with these voltages: VR101 = 2.0V VR104 VR102 = (see below) VR103 = 2.5V VR104 = 2.5V VR105 = 3.5V
For VR104VR102, set it to 2.25V, then adjust the other pots slightly to see if you can get reliable results. If not, increase VR104VR102 to 2.30V, repeat pot adjustments. If not, increase VR104VR102 to 2.35V, etc....upto VR104VR102 = 2.65V.
Note that all voltages above are not "set in stone", all the values will vary slightly, including VR104VR102 start voltage and end voltage.
Most important...the results of a pot change may NOT be immediate, so after each change, wait a few seconds for the circuit to settle in.
Charlie
Edit 6/6
Title: Re: My continuing CDROM2 problems
Post by: soop on June 20, 2011, 09:16:55 PM
Ace, thanks Charlie. I have a multimeter, pretty sure that will give me voltage.
Title: Re: My continuing CDROM2 problems
Post by: soop on June 25, 2011, 11:00:06 PM
Ok, I've found time to test this, but only one of the things is even close to the right voltage (second from the left, just after the white connector). Does the system have to be trying to read a disc at the time, or just plugged in?
Title: Re: My continuing CDROM2 problems
Post by: Charlie on June 26, 2011, 07:09:39 AM
Playing (or, at least, attempting to play!) an AUDIO cd. Run standalone, with power supply and headphones; NOT installed in interface unit. (Kind of hard to set it up for access to the pots in that configuration anyway.)
Since you are so mis-configured anyway, just press the PLAY button, then set the pots to the values given. Once you do that, pull the power plug, wait about 10 seconds, then start anew.
Try to get the audio cd to play track one at first. Turn the volume up full, you'll need to listen to the audio to fine-tune the starting point. You want no pops/crackles at full volume...they will vary as you tweak the pot, so go slowly. (Important: Make sure you have changed the caps first...you may mistake an audio hiccup caused by weak caps as an audio hiccup caused by mis-allignment. There is a subtle difference in the sound).
If/when you get track one audio cleanly, I can give you some hints on full tuneup.
Charlie
Title: Re: My continuing CDROM2 problems
Post by: soop on June 26, 2011, 10:03:16 PM
Ah, got everything except the audio CD - which makes perfect sense with no IFU. Right, I'll give it another crack soon, thanks for that!
Title: Re: My continuing CDROM2 problems
Post by: soop on June 30, 2011, 10:42:03 PM
argghh, this is almost impossible. I can't measure it and play it at the same time. Has anyone got a photo of the stock positions (if there is such a thing)?
Title: Re: My continuing CDROM2 problems
Post by: BlueBMW on July 01, 2011, 01:37:01 AM
Do you want to mail it to me to to try and fix it? I know you're in the UK but its pretty small and light.
Title: Re: My continuing CDROM2 problems
Post by: Charlie on July 01, 2011, 01:41:13 AM
Hmm, not sure I understand:
1. >>got everything except the audio CD - which makes perfect sense with no IFU<< The CD audio plays WITHOUT the IFU. In fact, IIRC, you can't even plug the headphone in if the CD is in the IFU. And I would have thought "Run standalone, with power supply and headphones; NOT installed in interface unit" was self-explanatory....or am I mis-interpretting your statement?
2. >>I can't measure it and play it at the same time<< Why not? I do! I presume you take the bottom off, and either set the unit up on a pedestal, or hang it over the edge of a table/bench. Either way, the power can be pluggged in, the headphone can be plugged in, the CD can be playing, and you can measure the pots while adjusting. In fact, you can even start the CD playing, then turn the unit on it's side (with the pots on top, of course) and do the measure/adjust that way.
Charlie
Title: Re: My continuing CDROM2 problems
Post by: soop on July 01, 2011, 04:32:40 AM
1. >>got everything except the audio CD - which makes perfect sense with no IFU<< The CD audio plays WITHOUT the IFU. In fact, IIRC, you can't even plug the headphone in if the CD is in the IFU. And I would have thought "Run standalone, with power supply and headphones; NOT installed in interface unit" was self-explanatory....or am I mis-interpretting your statement?
Sorry, I meant I was doing everything you'd suggested, except I was still using a PCE CD, not an audio CD
Quote
2. >>I can't measure it and play it at the same time<< Why not? I do! I presume you take the bottom off, and either set the unit up on a pedestal, or hang it over the edge of a table/bench. Either way, the power can be pluggged in, the headphone can be plugged in, the CD can be playing, and you can measure the pots while adjusting. In fact, you can even start the CD playing, then turn the unit on it's side (with the pots on top, of course) and do the measure/adjust that way.
Charlie
That was what I was having trouble with. I don't really have a suitable work surface as such, so I was doing it on a coffee table. Sideways is easier, but still confusing. I'm measuring the front 2 pins, and not only do I not get much of a readout ever (apart from that one pot), the disc isn't spinning. Put it back in the IFU, but now it won't spin up a disc. Back to square 1 (again) although I do have a photo of the last good settings.
Blu, thanks for the offer, but I really want to figure it out for myself. Even if it means I'm really sick of looking at PCEs at the moment (just finished RGB modding my PCE finally, and I can't test it yet because I still have to make the cable D:)
Title: Re: My continuing CDROM2 problems
Post by: Charlie on July 01, 2011, 05:04:00 AM
Aha! Take a break then!
Just a quick check: >> I'm measuring the front 2 pins<< I assume you mean the front 2 pots, and that you of course know to measure the center pin of each pot against ground.
Good luck Charlie
Title: Re: My continuing CDROM2 problems
Post by: soop on July 01, 2011, 05:17:05 AM
aha! No I didn't so that's probably why! And the one that was giving the good read must be the rheostat, it all begins to make sense!
But yeah, a rest is needed, I'mm off out for a bit. you guys have a good weekend, and I'll get back in the lab tomorrow!
Title: Re: My continuing CDROM2 problems
Post by: Charlie on July 05, 2011, 10:21:43 AM
It's been pointed out to me that, in my original post, I listed VR104 twice. I'll edit that post as soon as I check my notes.