Game gear-increasing the contrast causes complete shutdown

[bigsanta]

Received this  faulty GG today,no sound and dodgy screen and also when the contrast is turned up past a certain level ,this causes the GG to completely turn off ,this happens with batteries and with  the correct power supply .So i gave it the usual cap kit replacement ,all new caps for the sound and video .Sound is dot and video is ok ,but the shut down fault remains .

[bigsanta]

Both detachable boards have been swapped with ones from another game gear,still no change.Both fuses have been swapped with ones from the other GG and the back light also,aswell as the two blue coloured caps around the transformer and the transformer has also been swapped .

Still it switches off when the contrast reaches about below 2k ohms ,the screen also developes this shimmering effect when the contrast approaches this switch off point.I've also used a uk mega drive 1 power supply unregulated crap,9Vcc (ha) centre - and also a regulated supply 0f 9Vcc centre - 1 amp.

[jetblue]

a shimmering effect like liquid and when you press a button it shows like waves?

[bigsanta]

a shimmering effect like liquid and when you press a button it shows like waves?

Nope.When this shimmering effect begins ,it's like the effect you see when you turn down the refresh rate on your monitor,60 hz and below,a slow then faster flickering .

[l_oliveira]

Start by replacing all electrolytic capacitors on the power supply converter board.  If it doesn't help you may start swapping the caps on the main board too.

The reason is that when you move the contrast pot you change one of the polarization voltages that go to the LCD screen, causing the power supply to being drawn more than it's capable to supply.

Obviously on normal conditions there's no way of making the GG draw more current than the power supply can provide, but with old/worn out capacitors the power supply is less efficient.

[bigsanta]

I'll give that a whirl .

[bigsanta]

Well ,it worked .