Dead GFX9000

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By Louthrax

Prophet (2436)

Louthrax's picture

03-11-2016, 16:14

Hi all,

I ordered and received today the nice Intruder game from BitVision, but just discovered that my GFX9000 board (that I did not used for now more than 10 years) is dead. Even worse, if I plug that in an MSX machine, the power led won't turn on!

It's the v1.1 model from Sunrise:

Everything looks good on first visual inspection, except a small bump on an upper capacitor (maybe another smaller on one of the lower crystals)...

Has anybody already experienced that? Any idea on the first things to investigate?

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By jltursan

Prophet (2619)

jltursan's picture

03-11-2016, 16:38

Seems that there's a shortcircuit in the board. Check the resistance/continuity between GND and voltage pins (mainly +5V ones) in the connector.
I can see some capacitors that could be tantalum ones, they can be the cause as they blown quite easily.
Are you proficient with the solder iron?

By Louthrax

Prophet (2436)

Louthrax's picture

03-11-2016, 18:29

Yes, I already replaced capacitors on several machines with not much problems, but I've never seen a chemical capacitor causing a shortcut like that yet. The non-chemical capacitors are not looking like fried or exploded.
I'll start looking for shortcuts in the power chain and capacitors...

By RetroTechie

Paragon (1563)

RetroTechie's picture

03-11-2016, 18:50

Electrolytic capacitors are known to blow sometimes when they've been unused for a long time (like months or years+) and then suddenly charged to full voltage. But for aluminium electrolytics, that failure mode is usually easy to spot.

Tantalum capacitors (when not used for a long time) are known to fail sometimes when they encounter large charge current on first power up. A couple months ago I saw a tantalum capacitor pop (literally: in 2 halves! Shocked! ) when I pulled back into service a power supply it was in. This is really not uncommon, sadly. Eek!

Q1 also looks suspicious. Could you post a close-up of area around C16/Q1?

Btw: even though a GFX9000 is relatively 'recent' hardware, it's already hitting ~20 years age. Wouldn't hurt to just replace all electrolytic capacitors on this board. Cheap, easy.

By Jipe

Paragon (1594)

Jipe's picture

03-11-2016, 18:59

c1 c2 have strange aspect

By jltursan

Prophet (2619)

jltursan's picture

03-11-2016, 20:14

Quote:

Q1 also looks suspicious. Could you post a close-up of area around C16/Q1?

Indeed, it has something that resembles a burnt spot...

Quote:

c1 c2 have strange aspect

Hehe, they also looks like they have been boiled up

By Louthrax

Prophet (2436)

Louthrax's picture

03-11-2016, 20:22

So I did some checks on the capacitors, and it appeared that C14 and C15 had a very low resistance (around 2 ohms !) in both directions, so definitively something like a shortcut. I removed those 2 guys:

And it worked :)

Great success :RNFF:
Power LED is on, MSX is booting, and Intruder is running. The image is a bit distorted, but I did not resolder new capacitors yet, and I'll definitively replace all chemical capacitors. Tricky thing is that both sides of the board are used here for capacitors (I don't like that).

Lesson learned of the day: a chemical capacitor can definitively cause a bad shortcut in a PCB. Strange thing is I had no smoke, nice thing is that my MSX and their power supplies were not destroyed !

By Louthrax

Prophet (2436)

Louthrax's picture

03-11-2016, 20:24

Jipe wrote:

c1 c2 have strange aspect

It looks strange from top, but it's this type of capacitors:

Plastic seems a bit worn, maybe because of many insertion / removal of the cartridge.

By valkyre

Hero (643)

valkyre's picture

03-11-2016, 20:44

Glad your up and running. Enjoy intruder!

By RetroTechie

Paragon (1563)

RetroTechie's picture

03-11-2016, 21:50

Glad you located the problem!

Louthrax wrote:

Strange thing is I had no smoke, nice thing is that my MSX and their power supplies were not destroyed !

If a short circuit is 'good' enough, little heat is produced there, so then magic smoke tends to be released elsewhere... Shocked! (or if you're lucky, a fuse blows)

By Louthrax

Prophet (2436)

Louthrax's picture

03-11-2016, 22:28

RetroTechie wrote:

If a short circuit is 'good' enough, little heat is produced there, so then magic smoke tends to be released elsewhere... Shocked! (or if you're lucky, a fuse blows)

I've been lucky (in the good sense) I guess.

So I changed the capacitors and the display is now perfect Smile, so happy to play Intruder. I was not aware of the double-screen feature:


(yeah, my 2nd monitor is usually reserved for "Tate" games, will "just" need to rotate that beast...).

Wondering now if I could dump the game and flash it in MFR in order to have the SCC sounds without slot expander on my VG8020 ?
EDIT: Forget it, Intruder does not use a Konami SCC mapper, this can't work on MFR.

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