Sega Model 3 video issues

PCB problems and fixes
Post Reply
User avatar
Hydreigon
Please Continue...
Posts: 42
Joined: December 9th, 2018, 5:48 pm
Location: Milwaukee, WI
eBay: hydreigon223
Initials: HYD

Sega Model 3 video issues

Post by Hydreigon »

Game: Lost World Jurassic Park

After a few hours, ~6-8 hours, of uptime, one of these 3d issues would happen:
  • The female T-Rex would load wrong textures on some parts of the jaw and inside the mouth.
  • The 3d graphics would flicker.
  • No 3d graphics would show at all.
My initial thought was the boards weren't receiving the proper airflow due to some caked dust so I cleaned out the cage and boards; didn't fix the issue. Memory test shows rom and ram all good but displays a vertical dashed line of white pixels (disappears upon exiting the test mode however). I have not checked the voltages from the power supply yet. Could this be a video board issue?

If anyone else knows about Model 3, I noticed there is no mention of a step 1.5 on both the cpu and video boards of this Lost World boardset. I heard the only difference is the gpu overclocked on the video board. I'll save this discussion for a different thread.
User avatar
LEGENOARYNINLIA
Kameo-ken
Posts: 3429
Joined: March 19th, 2012, 7:22 am
Location: Finland
eBay: ⸨◺_◿⸩
Contact:

Re: Sega Model 3 video issues

Post by LEGENOARYNINLIA »

VF3tb which is also a Model 3 title is known to load wrong textures from time to time, and I think it's an awesome feature. :awe:



This happened just this Saturday. 8-)
Emulation's nice when done well
User avatar
outrun2
Posts: 253
Joined: August 18th, 2010, 6:25 pm
Location: Gloucestershire, UK
eBay: thefonzzz
Initials: GAZ

Re: Sega Model 3 video issues

Post by outrun2 »

Difficult to say, most likely a video board issue but step 1.5 video boards are more reliable than step 2 boards in my experience.

Could also be the ROM board so worth trying a different game on the stack if you can.

Always worth checking voltages particularly if you have an original Model 3 PSU which are known to be unreliable when they get old. A known 100% worker or better still a Sun PSU out of a Naomi is a better option.

For info step 1.5 boards just have 'Model 3 etc.' marked on them while step 2.0 and step 2.1 boards have 'Model 3 Step 2 etc.' marked on them. The .x isn't mentioned.
Wanted:
Sega Model 3 Emergency Call Ambulance ROM board or complete Step 2 boardset.
User avatar
Hydreigon
Please Continue...
Posts: 42
Joined: December 9th, 2018, 5:48 pm
Location: Milwaukee, WI
eBay: hydreigon223
Initials: HYD

Re: Sega Model 3 video issues

Post by Hydreigon »

My most likely guess is a certain component eventually shutting down from improper voltage and/or overheating. My next steps are to reseat/clean all the roms on the rom board, check/adjust power supply voltages and replace both fans. I'd appreciate any good suggestions for Sega Model 3 fan replacements, two of them.
User avatar
grantspain
Tech Head
Posts: 4823
Joined: August 17th, 2008, 4:23 pm
Location: down south

Re: Sega Model 3 video issues

Post by grantspain »

more likely the smt components on the video board are failing due to bad solder contact or even video ram breaking down
User avatar
Hydreigon
Please Continue...
Posts: 42
Joined: December 9th, 2018, 5:48 pm
Location: Milwaukee, WI
eBay: hydreigon223
Initials: HYD

Re: Sega Model 3 video issues

Post by Hydreigon »

Lowered the +5v and +3.3v down to near normal values. The issue got worse a few days after with the game freezing ~20 minutes after startup. My next step is now to check all boards and replace the fans.
User avatar
Hydreigon
Please Continue...
Posts: 42
Joined: December 9th, 2018, 5:48 pm
Location: Milwaukee, WI
eBay: hydreigon223
Initials: HYD

Re: Sega Model 3 video issues

Post by Hydreigon »

Nobody has any suggestions for replacing the case fans on a Sega Model 3? C'mon guys. I'm certain one of you has replaced them before and the factory fans can't last forever.

EDIT: May take a look at the whole pcb set one day so I can find out what fans are used.
Last edited by Hydreigon on June 15th, 2019, 6:37 pm, edited 1 time in total.
User avatar
nem
Needs a custom rank
Posts: 2768
Joined: August 17th, 2008, 6:59 pm
Location: Finland

Re: Sega Model 3 video issues

Post by nem »

The case is pretty snug, so I put some standard 20mm deep fans on the outside.
Post Reply