Forums

Sega Master System / Mark III / Game Gear
SG-1000 / SC-3000 / SF-7000 / OMV
Home - Forums - Games - Scans - Maps - Cheats - Credits
Music - Videos - Development - Hacks - Translations - Homebrew

View topic - Sega Master System messed up picture / weird numbers on screen

Reply to topic
Author Message
  • Joined: 28 Nov 2016
  • Posts: 1
Reply with quote
Sega Master System messed up picture / weird numbers on screen
Post Posted: Mon Nov 28, 2016 7:40 pm
Hi, I'm Sam and I'm new to this Forum :-)

While searching the internet for some hints on certaim master system related problems, I always found myself searching through old topics on this forum, so I guess ist only natural to finally post a question here.
So basically I hope you guys can help me with this one.

I’m trying to repair a Sega Master System I. The Problem is the picture is completely messed up. You see all kinds of numbers and characters. (See the pictures I have attached).



The first time I tried to power it on, nothing happened, the led didn’t light up. Therefore I replaced the 7805 and finally the Master System showed some signs of life.

Unfortunately it apeared that I stumpled into the next problem. The Master System powers on, I can hear the typical Sega boot up sound, but the screen is a mess.

Since I have a sega master system II for spares, I have started to replace all kinds of IC’s with working ones.

What I did so far:

Replaced some ICS:
- IC1 (Zilog CPU)
- IC2 ()
- IC6 & IC7 (Ram)
- IC9 (Sony RGB)

Replaced electrolyte Capacitors


I hope someone can help me with this problem or has an Idea what to try :-)
best regards
IMG_0110.JPG (177.06 KB)
IMG_0110.JPG
IMG_0109.JPG (143.15 KB)
IMG_0109.JPG
IMG_0111.JPG (169.8 KB)
IMG_0111.JPG

  View user's profile Send private message
  • Joined: 05 Sep 2013
  • Posts: 2334
Reply with quote
Post Posted: Tue Nov 29, 2016 9:24 am
Wow, I would say it's a VRAM problem... but you better wait some real expert :)
  View user's profile Send private message Visit poster's website
  • Joined: 13 Sep 2015
  • Posts: 2
Reply with quote
Post Posted: Wed Nov 30, 2016 6:37 am
Samysplace wrote
Hi, I'm Sam and I'm new to this Forum :-)

While searching the internet for some hints on certaim master system related problems, I always found myself searching through old topics on this forum, so I guess ist only natural to finally post a question here.
So basically I hope you guys can help me with this one.

I’m trying to repair a Sega Master System I. The Problem is the picture is completely messed up. You see all kinds of numbers and characters. (See the pictures I have attached).



The first time I tried to power it on, nothing happened, the led didn’t light up. Therefore I replaced the 7805 and finally the Master System showed some signs of life.

Unfortunately it apeared that I stumpled into the next problem. The Master System powers on, I can hear the typical Sega boot up sound, but the screen is a mess.

Since I have a sega master system II for spares, I have started to replace all kinds of IC’s with working ones.

What I did so far:

Replaced some ICS:
- IC1 (Zilog CPU)
- IC2 ()
- IC6 & IC7 (Ram)
- IC9 (Sony RGB)

Replaced electrolyte Capacitors


I hope someone can help me with this problem or has an Idea what to try :-)
best regards


Mine was exactly like yours.
I fixed it by replacing the two vram chips (NEC D4168C-15)
Good luck!
  View user's profile Send private message
  • Joined: 04 Dec 2016
  • Posts: 44
  • Location: Guarulhos - SP - Brasil
Reply with quote
Post Posted: Sun Dec 04, 2016 9:02 pm
Samysplace wrote
Hi, I'm Sam and I'm new to this Forum :-)...

Replaced some ICS:
..
- IC6 & IC7 (Ram)
...

IC6 and IC7 are VRAM ICs
Or you got bad replacement ICs or a bad SEGA 315-5124 VDP.
Try checking traces between VRAM ICs and SEGA 315-5124 VDP.
  View user's profile Send private message Visit poster's website
  • Joined: 14 Aug 2000
  • Posts: 487
  • Location: Adelaide, Australia
Reply with quote
Sega Master System messed up picture / weird numbers on screen
Post Posted: Wed Oct 31, 2018 10:31 am
Did you do all this in one go or did you try it out between steps and find there was no change or improvement between each step i.e.

1) Replaced IC1 (Zilog CPU)
2) No change or improvement
3) Replaced IC2 (PROM)
4) No change or improvement
5) Replaced IC6 & IC7 (VRAM)
6) No change or improvement
7) Replaced IC9 (Sony RGB)
8) No change or improvement
9) Replaced electrolyte Capacitors
10) No change or improvement

Was the SMS II fault free before it became a donor?

Is the circuit board nice and clean and free from dust, dirt, goo, corrosion, etc?
  View user's profile Send private message
  • Joined: 08 Sep 2018
  • Posts: 75
Reply with quote
Post Posted: Wed Oct 31, 2018 2:25 pm
Check your systems VRAM. Make sure there is no corrosion around it's traces or pins. If you can't see any damage then probe your vram and vdp to make sure all signal lines and power readings are correct. It's common for ram in old systems to fail so that should be your first area to check.
  View user's profile Send private message
  • Joined: 14 Mar 2013
  • Posts: 62
  • Location: Belgium
Reply with quote
Post Posted: Fri Nov 02, 2018 4:03 am
Guys, this is from 2016, just saying.
  View user's profile Send private message
  • Joined: 14 Aug 2000
  • Posts: 487
  • Location: Adelaide, Australia
Reply with quote
Post Posted: Fri Nov 02, 2018 11:25 am
Lol I didn't even notice the date. It just came up as an unread forum post. Hope it's been fixed since then XD
  View user's profile Send private message
Reply to topic



Back to the top of this page

Back to SMS Power!