The quest to save my CDROM base unit

[nodtveidt]

Okay, the gamebit showed up today in the mail, and the first thing I did was remove the whopping 3 security screws that the thing was held together with. I've looked the thing over a bit...no funky smells, no leaky capacitors, no obvious burnouts, no mechanical malfunctions. I know more about electronics than the average Joe but I'm no electronic engineer. Anyone have any suggestions as to what to look into? For the record, here's the details:

-The power supply is more than adequate (12V 1.5A), so that's not the problem
-The CDROM unit itself and the TG16 deck both work properly
-The TG16 deck worked with the original CDROM base unit, so I know the TG16->base unit interface is fine on the TG16 deck
-All the cables seem to be properly secured, so that's unlikely to be an issue
-The CDROM unit seems to make the connection at the two popup metal things, whatever that stupid thing is all about...I guess I could short that manually to make sure

If I get this thing working, I'm definitely going to replace all those damned stupid security screws with normal screws. What a pain in the ass!

I can post pics of the disassembled beastie if anyone wants, if that will help.

[nat]

The other day my TurboGrafx-CD deck died a mysterious silent death.

I was furious; my life was over.

A halfrack of Corona and a stroke later, I realized the "lock" knob on the right side of the unit (locks the CD player in place) had been bumped slightly when I was f*cking with the cables.

Apparently if this knob is in any position but completely locked, the entire unit will not power up. No white screen, no nothing.

You've probably already checked that, but hey, you never know-- it's worth a look. Even if it IS in the right position, it's a good place to start looking for malfunction. It's possible the switch inside isn't making contact-- maybe try bypassing the switch completely with a short jumper wire. Since I've never had the interface unit apart before, I'm not sure how things look in there, but I would imagine it would be fairly obvious what I'm talking about if you've got it open.

[nodtveidt]

I'm gonna see if I can pick up a multimeter today to do some tests. I'm guessing that it's either a problem in the power circuitry or in the main switch. I'm definitely going to do a few shorts if I can't pinpoint it with the multimeter.

[nodtveidt]

Okay, here's some results thus far.

I picked up a multimeter from Radio Shack, a nifty little 15 range jobby for like $23. I did some tests on the power system...so far, here's the scoop:

-The power into the console is normal. Just over 13V, which is expected because of our high line voltage.
-The power switch for the base unit works fine, I tested it both on and off.
-The 7805 shows zero voltage both in and out while the unit is powered on. No power out and I would think it's the voltage regulator itself, but no power in means there's a break somewhere else.
-I traced the circuit from the switch connector to the 7805. The common seems fine, there's only a single coil between the common and the 7805's pin 2. I don't think that's the problem, but it could be.
-There appear to be two +V lines into the console from the switch. One runs through another coil and somewhere into the mainboard. The other runs...to the second switch of the unit...the CDROM drive lock switch. This could potentially be the problem right here. I will intentionally short this area and then retest the 7805's power inlet.

EDIT: I did a resistance test on the switch's connection. At the circuit board, the switch checks out fine. I'll do some further tests to see if this is the cause of the problem.

[nat]

The other runs...to the second switch of the unit...the CDROM drive lock switch. This could potentially be the problem right here. I will intentionally short this area and then retest the 7805's power inlet.

That's what I was trying to suggest in my above message.

That seems like a very likely location for failure.

[nodtveidt]

SUCCESS!

The problem was a broken lead into the microboard that holds the CDROM locking switch. I shorted the circuit on the mainboard (so the switch always appears on) and the system powered on successfully. Gate Of Thunder is running as we speak.

[Keranu]

Fantastic, I'm glad to hear you fixed it!

[Necromancer]

Yippee - another system saved from the scrap heap!  While you got 'er cracked open, please take a few pics of a Turbo CD's guts.  Now quit f*cking around in this forum and go play some GoT. 

[nodtveidt]

Sorry, I didn't snap any pics while the thing was open...was too psyched to be able to play games again. Of course, GoT was the first thing I played through! Also, I found out that it can run some CDRs...we played thru Splash Lake but it froze up at the end. Oh well. Also played through my legit copy of Exile. Honestly though...the insides of the base unit aren't anything spectacular. It all makes me wonder though...there's got to be a way to "upgrade" the detachable CDROM unit.

[Necromancer]

No biggie nod - I was just thinking that you could take a few shots for posterity, but I doubt that they would be terribly exciting.  Certainly not as exciting as playing GoT after a hiatus.

[nodtveidt]

Well, I'm going to open it up again in a couple of weeks to fix it properly...the fix I made isn't optimal but it works. I just don't have the proper tools to fix it proper at the moment, but I will after we get paid again. I'll take a few pics then.