VideoGamePerfection.com | walter.comunello | Activity https://videogameperfection.com/members/walter-comunello/activity/ Activity feed for walter.comunello. Sun, 16 Aug 2026 16:37:50 +0100 https://buddypress.org/?v= en-US 30 hourly 2 56a67feba28b1489d228577461ce8eca walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/page/2/#post-70074 Thu, 09 Jul 2026 12:24:57 +0100 A miracle happened. The VA SG is alive. Having video artifacts on composite and an unstable RGB output, most likely caused by a faulty connector. Battery holder removed so she won’t keep clock, but no freezes or weird behaviour otherwise.

The PLL is healthy even after all that hot air blasted everywhere to remove ICs. Looks like the PCB is not…Read more

]]> 1563304303d310efb89b3824b6560e76 walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/page/2/#post-70055 Tue, 07 Jul 2026 18:32:54 +0100 ended up replacing all caps on daughterboard, mainboard and OCU board. Still wouldn’t focus after new laser.

Turns out, I forgot to remove the solder blob for ESD protection. Oops.

Afterwards the disc would start to spin but lens wouldn’t settle – with the help of my scope I calibrated FE slightly downwards, now it’s happily reading an audio CD,…Read more

]]> aad43bdae8d9b1ddbe06d4ef9a1a9668 walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-70042 Sun, 05 Jul 2026 18:47:32 +0100 resurrected a Saturn VA0.5 NTSC-J just by replacing 5 capacitors surrounding the PLL: CE18, CE19, CE20, CE21 and CE22.

No freezes so far. Next step: replace daughterboard caps and Optima-6.

]]> 0d9151d633dc788edea1488f8a55f472 walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-69869 Mon, 15 Jun 2026 15:00:15 +0100

Seems to be more of a manufacturing defect as older consoles don’t seem to have this issue.

extended rusting was found on the metal parts of the ODD. I suspect it was kept in a very damp place or water poured in at some point, was picked up and dried somewhat and left there. Many joints were completely detached from their copper pads although t…Read more

]]> abd3aecb6df13937f4a0632afa70d704 walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-69758 Mon, 08 Jun 2026 07:14:58 +0100

If you try to reflow a chip and notice the solder wont really stick, you have to take off the IC, dewick the solder and scrape the oxidation off then solder it back on.

exactly what I’m doing with the VA SG. It’s a terrible mess and basically all chips need this treatment. I have no idea if it will work at all after that, but I am confident vias…Read more

]]> 3f37716e596f5ef035c7836cafd073c6 walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-69709 Fri, 05 Jun 2026 07:11:54 +0100 thank you for your words of praise. But Goldilocks should still be considered in “pre-alpha state” since I believe it has somewhat destabilized the SMPC through DOTSEL, and hence should not be used (yet). It does output the correct frequencies though, but it needs a better interface with the Saturn. Maybe it just has to be driven by a transistor…Read more

]]> 30681554cde06bb31dc0a2d995f2a4ce walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-69703 Thu, 04 Jun 2026 15:37:26 +0100 I have swapped the SMPC with the one I found on the VA SG. It gave me the exact same issue, but then (just for kicks and giggles) I checked DOTCLK coming out of the PLL, and it was stable. I was appalled.

The Saturn is now perfectly fine. Powers up, reads games, as if it had been just purchased from a shop. Honestly I have no idea what…Read more

]]> ce149725f931048581cd3f023b2bb86d walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-69647 Tue, 02 Jun 2026 07:42:03 +0100 this morning the SMPC decided to die on me. Low impedance readings on DOTSEL and other pins on the D port of the internal microcontroller. This might explain other weird random behaviour but it’s too early to tell.

This morning I decided to do some cold boot tests, and the 26.846 DOTCLK wouldn’t stand still, giving black screen at power on.…Read more

]]> 66370aed3e085e01ecb43037c12f81fc walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/page/2/#post-69625 Sun, 31 May 2026 15:57:36 +0100 Update: the system is rock solid at 28.636MHz, but it freezes randomly at 26.846MHz. Most likely I have not understood how the video clock shifts and what exactly DOTCLK does. The only thing I can do is to acquire a working Saturn and try to probe DOTCLK and all the master clocks.

]]> 2c9fcd86a5ccc44fc4bbaded9d64e0ac walter.comunello replied to the topic Investigating the Black Screen Faults in the Sega Saturn in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/investigating-the-black-screen-faults-in-the-sega-saturn/#post-69616 Sun, 31 May 2026 14:32:40 +0100 so I have been working on a Model 1 Saturn with the black screen issue. You can see some data here. I did not want to go off topic too much so I’ll just put the rest here.

Long story short:

1-I’ve built a PLL replacement (I’ve named it “Goldilocks”) with a CDCE937 that works. Not perfect, but “just right” (hence the name).

2-Output clock(s)…Read more

]]> 5615a8a52aa4c114e8251e195b11974a walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/page/2/#post-69601 Sat, 30 May 2026 13:22:03 +0100 SCSP and VDP1 are conflicting over their clocks. I believe it’s because MCLK1 has a misshapen form. I have to work out the kinks. This goes beyond the PLL, this is a more widespread problem. Clocks are degrading all over the place and to get them back in shape is nothing short of wizardry.

]]> 02116248403daf2f5d69778075db12d4 walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/page/2/#post-69589 Fri, 29 May 2026 10:28:40 +0100 will be testing some sort of impedance matching on Goldilocks output, switching to 5V for buffers, then capacitance adjusting on each of the four MCLK zones:

 

VDP2 (IC14) and the SCU (IC5) are fed with MCLK0;

VDP1 gets MCLK1;

the two Hitachi CPUs chew on MCLK3;

the Toshiba controller has MCLK4.

 

(MCLK2 goes out through pin B66 of CN1 and…Read more

]]> 8121bae8b89cb6b3dc5b33a03cdfb8ca walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/page/2/#post-69584 Thu, 28 May 2026 19:57:23 +0100 so, apparently the PLL is not the only culprit in an aging Saturn. It has clock instabilities beyond the degradation of the HD49422.

I’ve seen this already – in an NTSC Mega Drive with freezing issues and in the EDCLK/VCLK degradation on a VA4 Model 1 Mega Drive with a 32X mounted. The NTSC-J Mega Drive needed a 75Ohm resistor in line with the…Read more

]]> d27f989219e5083aea6f7a7819964713 walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/page/2/#post-69574 Wed, 27 May 2026 18:53:26 +0100 can I post images or videos? because it looks like I have just resurrected a Model 1 Saturn.

DOTCLK is working so far – the Saturn boots and goes into the BIOS menu. Sound is effed up because there is no CD unit attached and normally the SCSP and sound clock derive from the 33MHz crystal on the Cd drive board.

Goldilocks is still an early…Read more

]]> 822b3e839c29a7277a0f082d5becaf1e walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/page/2/#post-69569 Tue, 26 May 2026 15:28:12 +0100 alright, news. Good news so far.

I’ve built both versions and programmed the 937 one. First testing gave ugly waves: 7.2Vpp ugly, some strong but short ringing, not sure if the Saturn tolerates such massive spikes and I cannot be sure that the 74HC04 between the PLL and the chips can absorb them. So, since I’m an electronic n00b and I can’t…Read more

]]> 6c4aff075cd646b0b4ad2c681f91b79a walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/#post-69496 Tue, 19 May 2026 19:13:04 +0100 @joostr14: if Goldilocks works (I’ve named it “Project Goldilocks”, I like how it sounds) it’ll revive dead Saturns since it aims to be a full PLL replacement in Model 1 Saturns. 937 would generate a single region frequencies whilst the 949 variant should be able imitate any region via the NPSEL point.

937 and 949 prototypes should be ready this…Read more

]]> c8eed55a9f671fcf67782f7661865a1a walter.comunello replied to the topic The Sega Saturn and the dreaded PLL chip in the forum Repairs and Upgrades https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/#post-69410 Tue, 12 May 2026 11:53:14 +0100 Hi,

I’ve been following this topic for a while and I’m also interested in a replacement.

I’m actually working on something based on CDCE PLLs. I’ve worked on schematics and I gathered all the info I thought I needed. I have the PCBs here and I’m waiting for the components to arrive. I still have to build the prototypes and see if they work.

I…Read more

]]>