Faulty GD-rom PCBs

[Tarnish]

Just something I was curious about after experiencing this a few times: How often do you guys run into a faulty Dreamcast where it turns out the GD-rom drive PCB is the one that is causing the problem?

Everyone keeps saying the laser is the Achilles' heel of the Dreamcast (which I don't doubt), I just found it a bit ironic that out of the 11 Dreamcasts I so far had my hands on, only 1 had a laser issue, while 3 had issues with the GD-rom dirve PCB. 1 had a broken lid sensor switch, while 2 seems to malfunction in weird ways:
- one of them recognises the discs fine, but after getting to the SEGA logo in the boot sequence, it goes back to the main menu, and also when opening the disc lid, it spins the disc in the opposite direction instead of stopping it
- the other is pretty similar that it recognises the discs fine, but after the SEGA logo it just goes back to the main menu. Also, when trying it out with an audio CD, it seems to read and play it fine, except it doesn't output any sound, even tho the boot up and menu button sound effects play, so it's not an issue with AV cables. This one doesn't spin the disc in the opposite direction when opening the lid however, and on rare occasions it does boot up games and plays music properly.

(Just to note, it's definitely the boards that are at fault in these cases, as I did troubleshooting by swapping out the laser pick-ups, motors etc. to known good components to see what is actually causing the problem.)

So it's probably just my luck, but it never really dawned on me that the GD-rom drive board can go bad as well. The laser, motors, ribbon cable, PSU are the usual suspects.

[simfan]

I agree with your point of view. When I receive a fault unit which cannot load disc but spins, I will check the ESR value of the capacitors, and replace those with high ESR value. I cannot prove anything but I trust this build a stable ground for me to install and tune the SPU 3200 laser unit.

[simfan]

Recently I repaired two DCs which not reading discs by recapping those capacitors with ESR over 20oms. Now they read discs smoothly and silently.

[butoia]

Recently I repaired two DCs which not reading discs by recapping those capacitors with ESR over 20oms. Now they read discs smoothly and silently.

Hi, can you post a scheme with the capacitors to recap? Thanks in advance!

[fafadou]

https://dragoncity17.wordpress.com/2013 ... parations/

You have all informations here and spare components for 3€.

[Flatfire]

Reviving this, apologies to anyone who'd rather not but I'm hoping someone may have done this operation using some SMD electrolytic caps rather than the larger electrolytic caps used in dragoncity17's blog post. There also isn't much information detailing the removal of the existing caps, and whether it's possible to do so just with basic soldering equipment or if a soldering station is preferred.

Thank you!

[PengoJetz]

Hi, I recap a lot of GD-rom drives - they are a quick job to do if you have some experience with soldering. The only hard part is taking the old SMD drum caps off without tearing the solder pads.

I use a pair of pliers to grip them, then turn counter-clockwise until they come off. Some of them will just drop out without much trouble, but others may still leave you with the plastic stumps that need to be carefully pried off with a small screwdriver.

Then just use your soldiering iron and a bit of braid to wipe feet off. Some of these old caps are starting to leak - need to clean up with IPA to neutralize before putting down some flux and placement of your new caps.

There are 3 types of caps you generally need for the board logic, but the number vary between VA0 and early and later model of VA1:

47uf 6.3v (usually 3 of them)
100uf 6.3v (usually 5 but sometimes 6)
100uf 16v (2 on most VA1)

I have seen some people just drop in 16v for all of the 100uf caps, but I prefer to stick with the same voltage for the 6.3v ones.

I use 1206 ceramic caps because they aren’t polarized and easier to solder on each side. Don’t need to use SMD replacements - hole-thru caps will work but need to bend the feet flat with the board. If you use electrolyte, polymer or tantalum caps make sure you check the polarity is correct on all of them before testing, or something bad will happen when powered on.

Console5 wiki has the cap map for both models (PCB #2)
https://wiki.console5.com/wiki/Dreamcast

[onlycodered]

@PengoJetz I just bought a VA1 with a bad GD-ROM drive. Already have a GDEMU going in but curious on whether or not I can get the original GD-ROM drive working again. I took a look at the PCB and all the caps visually appear fine. Do you find in your own experience that even with a visual inspection replacing the caps will resolve issues? I know that's kind of a broad question, but it sounds like you have a lot of experience with these.

If it helps at all, when I close the lid the disc spins slowly, stops, spins slowly again, stops and repeats this until it gives up. The disc at no point reaches full speed. I've confirmed the disc drive is the culprit as I verified a known good drive works just fine in this DC. Would love to hear your thoughts.

[PengoJetz]

On drum type capacitors , the electrolyte fluid will evaporate over time but you will not always see signs of leaking. Given the age (25years plus) it’s worth a replacement anyway to keep them going.

I can usually resolve 7/10 of these after a recap but even then there can be other issues. A very small laser pot adjustment may also be needed to get the motor moving again.

Could also be a problem with the lid switch sensor if it spins up but stops when you close the lid. You could try cleaning with a few drops of IPA and toothbrush. If it’s broken, you can still buy a new replacement switch from Digikey:
https://www.digikey.com/en/products/det ... 0AFEAugL5A

A lot of these are just breaking down due to motor issues, not much you can really do there other than try swapping parts with other drives to see if there’s any improvement.

[onlycodered]

Thank you for your detailed explanation. The lid switch sensor should be fine since it worked when I swapped my known good GD-ROM drive in. Looks like Console5 has a GD-ROM cap kit for $6.50. Not a huge risk since I’m dropping a GDEMU in this DC to flip on eBay. Want to try and fix the GD-ROM drive as well so I have a spare. I’ll let you know how it goes. I may just try swapping the laser/PCB from my known good unit with this one as well to narrow down the root cause.