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Sega Master System messed up picture / weird numbers on screenPosted: 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 :-)
||Posted: Tue Nov 29, 2016 9:24 am|
|Wow, I would say it's a VRAM problem... but you better wait some real expert :)|
||Posted: Wed Nov 30, 2016 6:37 am|
Mine was exactly like yours.
I fixed it by replacing the two vram chips (NEC D4168C-15)
||Posted: Sun Dec 04, 2016 9:02 pm|
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.
Sega Master System messed up picture / weird numbers on screenPosted: 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?
||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.|
||Posted: Fri Nov 02, 2018 4:03 am|
|Guys, this is from 2016, just saying.|
||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|