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 - Game Gear turn off (contrast wheel)

Reply to topic
Author Message
  • Joined: 31 May 2021
  • Posts: 4
Reply with quote
Game Gear turn off (contrast wheel)
Post Posted: Mon May 31, 2021 12:13 pm
Hi,

this is my first post. I've been consulting for a while this forum to find fixes for my GGs but I'm at point that can't find info on my exact problem.

I have a GG with the HV circuit removed and installed a homemade backlight led circuit. Of course I did the recapping on al the boards (power and sound included and tested on other GGs). But it happens that the GG powers off immediately after power on.

It is clear that is entering the self protection mode. So I been reading a lot and end up removing the contrast wheel. Now the GG powers on and I can hear the game sound but of course, the screen is black. If I shot the 2 and 3 pins of the contrast circuit, which is supposed to put the contrast at a 70%, the GG powers off. This behavior discards the contrast wheel as the problem and points in to another direction.

I'm a bit lose and don't know what else can I try or check to find out the real problem.

Can you please give me some clues or things I can try to find out the real problem?

Thanks and regards
  View user's profile Send private message
  • Joined: 02 Jun 2021
  • Posts: 1
Reply with quote
Post Posted: Wed Jun 02, 2021 2:12 pm
Hello cocoeru,

I have got the same problem, GG turns off after 1 sec. Red LED lights on and 1 sec after plof, GG turns off. I read a lot about it. I read that could be a problem on the LCD or backlight tube. I removed them both and still same problem. So I don't know what to do now.


Quote
If I shot the 2 and 3 pins of the contrast circuit,

What do you mean when you say that ?
I'd like to try removing the contrast wheel, but if I can bridge pins 2 and 3 or trying anything to check the contrast wheel without removing it that would be cool.

For your problem, I suppose you double checked caps connections (continuity) and polarity.

Regards
  View user's profile Send private message
  • Joined: 05 Sep 2013
  • Posts: 2943
Reply with quote
Post Posted: Wed Jun 02, 2021 2:52 pm
cocoeru wrote
If I shot the 2 and 3 pins of the contrast circuit, which is supposed to put the contrast at a 70%, the GG powers off.


have you tried to use a resistor between those two pins?
  View user's profile Send private message Visit poster's website
  • Joined: 31 May 2021
  • Posts: 4
Reply with quote
Post Posted: Mon Jun 07, 2021 2:50 pm
Ruchi wrote
Hello cocoeru,

I have got the same problem, GG turns off after 1 sec. Red LED lights on and 1 sec after plof, GG turns off. I read a lot about it. I read that could be a problem on the LCD or backlight tube. I removed them both and still same problem. So I don't know what to do now.


Quote
If I shot the 2 and 3 pins of the contrast circuit,

What do you mean when you say that ?
I'd like to try removing the contrast wheel, but if I can bridge pins 2 and 3 or trying anything to check the contrast wheel without removing it that would be cool.

For your problem, I suppose you double checked caps connections (continuity) and polarity.

Regards


Hi, sorry, by "shot" I mean short (bridge). It is supposed that if you short pin 2 and 3 of the contrast pins, the backlight goes to 70%. By the way, removing the contrast wheel is very easy. Even though, that is what the contrast wheel do, bridge pin 2 and 3, but with a variable resistance in between.

sverx wrote

have you tried to use a resistor between those two pins?


Yes, same result, protection mode. Also I disassembled the wheel, cleaned it and tested it with a multimeter and seems ok. I also have another wheel, but I get the same behavior if I install it in the GG.

Thanks for your replies.
  View user's profile Send private message
  • Joined: 25 Nov 2015
  • Posts: 121
Reply with quote
Post Posted: Thu Jun 10, 2021 8:14 am
cocoeru wrote
Ruchi wrote
Hello cocoeru,

I have got the same problem, GG turns off after 1 sec. Red LED lights on and 1 sec after plof, GG turns off. I read a lot about it. I read that could be a problem on the LCD or backlight tube. I removed them both and still same problem. So I don't know what to do now.


Quote
If I shot the 2 and 3 pins of the contrast circuit,

What do you mean when you say that ?
I'd like to try removing the contrast wheel, but if I can bridge pins 2 and 3 or trying anything to check the contrast wheel without removing it that would be cool.

For your problem, I suppose you double checked caps connections (continuity) and polarity.

Regards


Hi, sorry, by "shot" I mean short (bridge). It is supposed that if you short pin 2 and 3 of the contrast pins, the backlight goes to 70%. By the way, removing the contrast wheel is very easy. Even though, that is what the contrast wheel do, bridge pin 2 and 3, but with a variable resistance in between.

sverx wrote

have you tried to use a resistor between those two pins?


Yes, same result, protection mode. Also I disassembled the wheel, cleaned it and tested it with a multimeter and seems ok. I also have another wheel, but I get the same behavior if I install it in the GG.

Thanks for your replies.


It seems to be a loose contact/soldering somewhere; try to check where the pressure goes inside the GG when you roll/press the wheel, it can be a fake soldering somewhere, probably in some power-related component. Try also to replicate the proble without pressing the wheel but near it to see if it happens; if so it is not a wheel problem.
  View user's profile Send private message
  • Joined: 11 Mar 2006
  • Posts: 73
Reply with quote
Post Posted: Thu Jun 10, 2021 10:14 am
I had the same problem. I had to power it on for about 20 times for the console to stay on. the power board was tested in another consoles. I replaced various parts and no luck. I got angry and ripped the screen. The console now stays on. Maybe the problem is with the ic's on the lcd?
  View user's profile Send private message
  • Joined: 31 May 2021
  • Posts: 4
Reply with quote
Post Posted: Wed Jun 16, 2021 10:56 am
asper wrote


It seems to be a loose contact/soldering somewhere; try to check where the pressure goes inside the GG when you roll/press the wheel, it can be a fake soldering somewhere, probably in some power-related component. Try also to replicate the proble without pressing the wheel but near it to see if it happens; if so it is not a wheel problem.


Can't be that because I desoldered the wheel completely and had the same issue if I bridge pins 2 and 3.
  View user's profile Send private message
  • Joined: 31 May 2021
  • Posts: 4
Reply with quote
Post Posted: Wed Jun 16, 2021 11:00 am
gorgyrip wrote
I had the same problem. I had to power it on for about 20 times for the console to stay on. the power board was tested in another consoles. I replaced various parts and no luck. I got angry and ripped the screen. The console now stays on. Maybe the problem is with the ic's on the lcd?


May be, but the screen came from a working unit that was replaced with a McWill. I can try to desolder the LCD and see if it stays on. But I don't like to play around with soldering and the soldering the LCD because it's a bit fragile and every time you do that, it gets wicker.
  View user's profile Send private message
Reply to topic



Back to the top of this page

Back to SMS Power!