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Hello (sorry for the long post),

I'm wondering if anyone can help me. I'd like to know more about putting decoupling capacitors on the game gear (main board). Does anyone have experience with this and do you find it effective to reduce static,buzzing, electronic noise on the game gear?

I've read up a bit and found out that you can put a decoupling capacitor on the power board on the 5 v pin and ground pin. Any size from 460 uf to 1000 uf.

Also, I came across an old topic, 2015, in this forum and read:

"By the way, to prevent shutdown problems as I had previously (because of the larger decoupling capacitors), I increased the CPE (C1) from 0.68uF to 4.7uF. This way, the time constant for the short circuit protection (t = C1*0.6) increased from the default 0.4s to 2.82s :D

This is the only way I can have a couple of 1000uF capacitors inside the GG to minimize ripple. I should add some 100nF ceramic capacitors too.

I have to say, the machine feels (and appears) as brand new. "

So I'm lost on where to put the 1000 uf capacitors and where the cpe c1 capacitor is to change it.

And final question, someone told me that adding decoupling capacitors will slightly drain your batteries more. Wondering if that is in fact true.

Thanks a lot!

I can't imagine adding such a huge capacitance as 1000uF is a good idea.

For audio problems it would be related to the circuitry on the sound board, specifically the TDA2822 amplifier that drives the headphone jack and speaker at location IC1.

Comparing the schematic (Game Gear Service Manual VA1) to the amplifier datasheet, Sega uses a 100uF and 0.1uF capacitor for decoupling on pin 2 of IC1, whereas the manufacturer uses 10uF.

If I was trying to isolate audio issues related to digital noise I'd keep the original caps and add an additional 10uF there to be compliant with the manufacturer's suggested implementation, and perhaps experiment with an additional 1uF and 0.01uF cap as well.

Maybe as a last-ditch effort if everything else failed you could try a 220uF or 470uF but I wouldn't go higher.

Thank you for the insight about the sound board.

The person who put a few 1000 uf on.... I believe he did it on the main board to help with ripple and electronic noise. So for example, when you first turn on the game gear, with the sound turned off...

You hear a hum and buzz. I believe this can be heard more with things like a new LCD.

I know where to put a decoupling capacitor on the power board. I'm wondering if anyone knows what he is talking about as far as the main board. And changing the cpe c1 from .68 uf to 4.7 uf.

Much appreciated

Author	Message
GGBat Joined: 28 Oct 2020 Posts: 5	Game Gear Help - Ripple/Electronic noise Posted: Wed Oct 28, 2020 2:28 pm
GGBat Joined: 28 Oct 2020 Posts: 5	Hello (sorry for the long post), I'm wondering if anyone can help me. I'd like to know more about putting decoupling capacitors on the game gear (main board). Does anyone have experience with this and do you find it effective to reduce static,buzzing, electronic noise on the game gear? I've read up a bit and found out that you can put a decoupling capacitor on the power board on the 5 v pin and ground pin. Any size from 460 uf to 1000 uf. Also, I came across an old topic, 2015, in this forum and read: "By the way, to prevent shutdown problems as I had previously (because of the larger decoupling capacitors), I increased the CPE (C1) from 0.68uF to 4.7uF. This way, the time constant for the short circuit protection (t = C1*0.6) increased from the default 0.4s to 2.82s :D This is the only way I can have a couple of 1000uF capacitors inside the GG to minimize ripple. I should add some 100nF ceramic capacitors too. I have to say, the machine feels (and appears) as brand new. " So I'm lost on where to put the 1000 uf capacitors and where the cpe c1 capacitor is to change it. And final question, someone told me that adding decoupling capacitors will slightly drain your batteries more. Wondering if that is in fact true. Thanks a lot!

Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Posted: Wed Oct 28, 2020 3:10 pm
Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	I can't imagine adding such a huge capacitance as 1000uF is a good idea. For audio problems it would be related to the circuitry on the sound board, specifically the TDA2822 amplifier that drives the headphone jack and speaker at location IC1. Comparing the schematic (Game Gear Service Manual VA1) to the amplifier datasheet, Sega uses a 100uF and 0.1uF capacitor for decoupling on pin 2 of IC1, whereas the manufacturer uses 10uF. If I was trying to isolate audio issues related to digital noise I'd keep the original caps and add an additional 10uF there to be compliant with the manufacturer's suggested implementation, and perhaps experiment with an additional 1uF and 0.01uF cap as well. Maybe as a last-ditch effort if everything else failed you could try a 220uF or 470uF but I wouldn't go higher.

GGBat Joined: 28 Oct 2020 Posts: 5	Posted: Thu Oct 29, 2020 1:30 am
GGBat Joined: 28 Oct 2020 Posts: 5	Thank you for the insight about the sound board. The person who put a few 1000 uf on.... I believe he did it on the main board to help with ripple and electronic noise. So for example, when you first turn on the game gear, with the sound turned off... You hear a hum and buzz. I believe this can be heard more with things like a new LCD. I know where to put a decoupling capacitor on the power board. I'm wondering if anyone knows what he is talking about as far as the main board. And changing the cpe c1 from .68 uf to 4.7 uf. Much appreciated

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