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 - [SOLVED] Another weird Master System black screen

Reply to topic
Author Message
  • Joined: 10 May 2015
  • Posts: 22
Reply with quote
[SOLVED] Another weird Master System black screen
Post Posted: Thu Jan 20, 2022 1:16 pm
Last edited by Fisher on Sat Jan 22, 2022 7:43 pm; edited 2 times in total
Hello.
I have received as a "gift" a "dead" TecToy Master System 1 PCB and was trying to fix it.
So far so good everything was going fine, I was harvesting many parts from the junk pile and putting them in the place of the missing ones.
After finally being able to turn it on, I discovered that the BIOS chip was busted, getting very hot very quickly. I socketed it so I could try other options.

The last thing that was missing was the crystal.
The original is 10.726834 Mhz, the one I got is 10.1378 Mhz.
As expected, the console booted, but the video was black and white and with some jumping lines and weird random colors around.

I've got a proper frequency crystal, a weird thing happened.
The console simply shows a black screen with some faint vertical lines when I use the crystal that has the proper frequency but boots fine with the color problem with the other one.

I just don't know what to look for next, can someone please give me some ideas?
20220116_190154 (2).jpg (1.28 MB)
After
20220116_190154 (2).jpg

  View user's profile Send private message
  • Joined: 10 May 2015
  • Posts: 22
Reply with quote
Post Posted: Sat Jan 22, 2022 7:41 pm
I found it!
I've read that a black screen has big chances of being caused by either the Z80 or his RAM.
I first socketed the RAM and tried a 6264 I had lying around with no results, but after I changed the Z80 everything did come back to normal, I guess it's somewhat damaged.

What could have fried the BIOS and damaged the Z80 is a mistery to me... maybe a lighting or some kind of power surge?

Anyway thanks to anyone that at least have read this, hope this small information can help someone else in the future.
  View user's profile Send private message
  • Joined: 14 Oct 2008
  • Posts: 428
Reply with quote
Post Posted: Sun Jan 23, 2022 5:02 am
Someone using an incorrect power adapter at some point is maybe a potential cause?
  View user's profile Send private message
  • Joined: 10 May 2015
  • Posts: 22
Reply with quote
Post Posted: Sun Jan 23, 2022 1:48 pm
Probably.
But it was missing the transistor and the regulator, as can be seem on the pictures.
The zener diode was fine.

In case someone is curious, I've got some pictures and even a small video here: https://drive.google.com/folderview?id=1DJzcpGi4BIG6iMuHq8F8mJTyh2EuBA9E
  View user's profile Send private message
Reply to topic



Back to the top of this page

Back to SMS Power!