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: 2542
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: 519
  • 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: 212
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: 519
  • 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
  • Joined: 12 Nov 2019
  • Posts: 4
Reply with quote
Post Posted: Tue Nov 12, 2019 4:05 pm
I believe I'm having the same problem.

I was playing Shinobi with no problems at all, left the game running for a bit (5min or so) to do some stuff and when I looked back at the screen...SURPRISE! the graphics were all garbled. I was hoping it was a game glitch... no big deal...after rebooting the console (a SMS2 PAL-G) everything was still the same which I immediately thought it was the game cartridge, then rebooted with no cartridge and Miracle World was never the same place again :(

I disassembled the console and found no traces of burned stuff or anything, it actually looks like new, this was my first console but I was always very careful with it.

I took some photos from the TV, the sound is fine and the colors too (the photos may misguide you about the colors but they are fine).
I've searched for cracked solder points (mainly at IC6 and IC7) but, even taking in count my limited knowledge about this stuff, I can't find anything visibly wrong.

Do you think this could be anything besides VRAM problems implying changing chips?

Thanks
P_20191111_225703.jpg (372.1 KB)
P_20191111_225703.jpg
P_20191111_225737.jpg (749.27 KB)
P_20191111_225737.jpg
P_20191111_225648.jpg (334.51 KB)
P_20191111_225648.jpg

  View user's profile Send private message
  • Joined: 08 Sep 2018
  • Posts: 212
Reply with quote
Post Posted: Tue Nov 12, 2019 7:01 pm
Ikari wrote
I believe I'm having the same problem.

I was playing Shinobi with no problems at all, left the game running for a bit (5min or so) to do some stuff and when I looked back at the screen...SURPRISE! the graphics were all garbled. I was hoping it was a game glitch... no big deal...after rebooting the console (a SMS2 PAL-G) everything was still the same which I immediately thought it was the game cartridge, then rebooted with no cartridge and Miracle World was never the same place again :(

I disassembled the console and found no traces of burned stuff or anything, it actually looks like new, this was my first console but I was always very careful with it.

I took some photos from the TV, the sound is fine and the colors too (the photos may misguide you about the colors but they are fine).
I've searched for cracked solder points (mainly at IC6 and IC7) but, even taking in count my limited knowledge about this stuff, I can't find anything visibly wrong.

Do you think this could be anything besides VRAM problems implying changing chips?

Thanks


It looks like a VRAM issue. sometimes there is just no external tell that lets you know a chip is bad. Cheap ram that have broken often have issues where cells will just die or stop operating properly when the system warms up. (brings back commodore 64 vibes lol) I recommend replacing your VRAM first but try just reflowing pins to each IC before getting new ram. you never know it may just be a dead solder joint.
  View user's profile Send private message
  • Joined: 05 Sep 2013
  • Posts: 2542
Reply with quote
Post Posted: Wed Nov 13, 2019 9:57 am
I would expect a malfunctioning VRAM chip should give a different outcome than what I see, but you might have a chip that it's malfunctioning only sometimes.

Did you try leaving the Master System to cool off and test again?
  View user's profile Send private message Visit poster's website
  • Joined: 12 Nov 2019
  • Posts: 4
Reply with quote
Post Posted: Wed Nov 13, 2019 12:58 pm
First of all thank you IllusionOfMana and sverx

IllusionOfMana
I have reflowed all the 56 points (2x28) but nothing changed :(

sverx
I tested the console in different days. It shows this scrambled image as soon as I turn it on.
Can you please elaborate more on this?
Quote
I would expect a malfunctioning VRAM chip should give a different outcome than what I see



I can try to get a working SMS2 with a scratched/beaten shell for cheap and just change the board but I really would like to know what the problem is and save my old board, the thing is... removing components from one board to another for testing it's always a bit risky.

Do you guys know where can I get those loose vram's? That way, if something goes wrong, I wont be putting in risk another board. I'm also taking in count that Samysplace (topic creator) replaced some ICS to no avail
  View user's profile Send private message
  • Joined: 08 Sep 2018
  • Posts: 212
Reply with quote
Post Posted: Wed Nov 13, 2019 2:41 pm
I mean, It looks like its just 28 pin DRAM but I could be wrong. If it is, you could probably easily find a replacement on ebay for cheap.
  View user's profile Send private message
  • Joined: 05 Sep 2013
  • Posts: 2542
Reply with quote
Post Posted: Wed Nov 13, 2019 2:53 pm
Ikari wrote
sverx
I tested the console in different days. It shows this scrambled image as soon as I turn it on.
Can you please elaborate more on this?
Quote
I would expect a malfunctioning VRAM chip should give a different outcome than what I see


I'm just wondering how could a faulty chip still give you perfect areas in the image. But I'm in no way expert, and the chip might be just partially broken anyway.

Probably we need some VRAM test tool. But again, if there's an interrupted connection, any VRAM tool will report the VRAM as broken.

edit: wait, are there multiple VRAM chips? Because comparing the Alex Kidd screen you posted and what I see in my emulator, it seems just some parts of VRAM are gone! You can't read "PUSH" but you can read "START B*TTON" - the U is reusing the tile that's stored earlier, for the PUSH part...
  View user's profile Send private message Visit poster's website
  • Joined: 12 Nov 2019
  • Posts: 4
Reply with quote
Post Posted: Wed Nov 13, 2019 3:26 pm
I believe there are two @ IC6 and IC7
I can test it with more games but it seems that the hero sprite never gets affected, at least in the examples I've showed, Alex Kidd and Ryu Hayabusa never get messed up, this affects mainly the backgrounds.
Anyone knows if this could be a hint to prioritize the change of a specific IC or anything else?
  View user's profile Send private message
  • Joined: 14 Aug 2000
  • Posts: 519
  • Location: Adelaide, Australia
Reply with quote
Sega Master System messed up picture / weird numbers on screen
Post Posted: Thu Nov 14, 2019 2:25 am
There are 2 DRAM chips used for VRAM which are wired in a parallel 16-bit data bus. These NEC 4168 chips can still be purchased around the place. It's totally possible for a portion of the DRAM to become faulty.

This could be a faulty VDP, faulty VRAM, or faulty connection between the two. I don't think it's a problem with the connection between the VDP and CPU, but I could be wrong.

Before contemplating removing chips, I would rule out power supply and the PCB if you haven't done that already. (Heck I would check every pin on the VDP given how painful a chip replacement is.)

Measure the power to the VRAM and VDP and check that it's 5 volts. It may be worth replacing the electrolytic capacitors near the VRAM chips to rule them out as faulty.

For the PCB, grab a copy of the service manual from the Development section. It contains the schematic. Check each line between the VDP and VRAM chips for continuity.

In terms of prioritising chip replacement if you get to that stage, the DRAM can still be purchased, the VDP not so much.

Good luck!
  View user's profile Send private message
  • Joined: 12 Nov 2019
  • Posts: 4
Reply with quote
SOLVED!
Post Posted: Mon Nov 18, 2019 1:06 pm
Last edited by Ikari on Tue Nov 19, 2019 9:50 am; edited 1 time in total
I was following asynchronous tips and at first everything seemed normal but the problem remained.

Then I was like, well guess I’m going to do gentle pushes almost everywhere just to see if there’s any reaction.

In the meantime I bought a very worn SMS2 (no cartridge lid etc) just to change the board and I thought of modding (led+composite) the new “hybrid” console (old shell / new board).

I started to crocodile clip the voltage regulator to simulate a led mod, in case I’ll do anything wrong I’ll just be damaging my already damaged board. Suddenly I looked at the TV and there were REALLY less graphic glitches, I was like wow…I did something that helped solve the problem but I wasn’t sure what lol. Then I just turned the console off and on and everything went back to normal. I’ve turned it off and on about 10 times after that and it is still working fine.

I can’t tell you for sure where the problem was(is?) but my bet is, and as asynchronous said, the capacitors between and around the VRAM chips because it was after checking continuity and pushing there that it started working again.

Thank you guys!
  View user's profile Send private message
  • Joined: 16 Dec 2004
  • Posts: 473
  • Location: El Cerrito, CA
Reply with quote
SG-1000II Video Problem
Post Posted: Mon Nov 18, 2019 11:16 pm
Hi, I just purchased a SG-1000 model 2 on eBay that has a similar issue.

Does this also look like a video ram issue?
sg1kii.jpg (205.88 KB)
SG1K
sg1kii.jpg

  View user's profile Send private message Visit poster's website
  • Joined: 08 Sep 2018
  • Posts: 212
Reply with quote
Post Posted: Tue Nov 19, 2019 4:06 am
Raccoon Lad wrote
Hi, I just purchased a SG-1000 model 2 on eBay that has a similar issue.

Does this also look like a video ram issue?


yes it does
  View user's profile Send private message
Reply to topic



Back to the top of this page

Back to SMS Power!