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A color version of the Nintendo Game Boy, released in 1998. Repair of this device is straightforward.

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Cannot get sound from the main speaker

Hello everyone. I am at my wits end here trying to repair a special Pikachu edition of a Gameboy Color. I have read several articles saying this edition seems to have a lot of sound issues. So, these are the things that are working and not working and what I have replaced/tested.

Currently, there is no sound coming out of the main speaker. I replaced it with a brand new speaker (twice) and still no luck. I have conducted a conductivity test on the speaker itself (good), on the wires leading from the speaker to the motherboard (good), and on the motherboard solder joints (good).

I have tested the headphone jack. When headphones are plugged in, I do get sound from them. Spinning the volume control does increase and decrease the sound. Unplugged and no sound from the main speaker. Tested conductivity from the headphone disconnect to the motherboard and it’s good (so the speaker disconnect doesn’t appear to be stuck). Just to be sure, I plugged in and out a jack a dozen times just in case to loosen it. Still no sound.

I tested the original speaker that came with the Gameboy, it actually still has conductivity so it appears to be working fine. This Gameboy was stored for the past 10 - 12 years in a cardboard box in an outdoor garage. No water damage to the box but it was subjected to extreme conditions (-10 to -60 degree winters, 80 to 100 degree summers). No batteries were stored in the Gameboy so no erosion or acid damage. Before being placed into storage, the speaker worked fine. All other aspects of the Gameboy seem to be working just fine; no screen distortion, powers on and off fine, and plays any game put into it.

I can’t figure it out and it’s bugging me. Sure, I can play games with headphones on but I REALLY want sound from the main speaker. If I’m missing something, I can’t figure out what it is. Any help (besides buying a new GBC, hehe) would be helpful. Thank you.

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Hi,

Check that there is an earth at the SW test point on the circuit board (goes to pin #6 U3 IC) when there are no headphones inserted.

I realize that you said that you “Tested conductivity from the headphone disconnect to the motherboard and it’s good (so the speaker disconnect doesn’t appear to be stuck).” but I wasn’t sure whether you tested it back all the way to the IC.

If it tests OK then here’s an image taken from the service manual for a Game Boy Colour showing the audio section. Hopefully it is the same for your edition.

Block Image

(click on image to enlarge for better viewing)

Some things to check and do to try and isolate the problem:

Check that the capacitors marked with the green arrows are OK and not either open circuit or short circuit. For example if C38 was open circuit there would be no audio through the speaker. If C14 were short circuit it would shunt the audio from going through the speaker and if C27 were faulty it would affect how the audio amp for the speaker in the IC would function (there are two amps in the IC, one for the headphones and one for the speaker).

Unsolder the non earth side of the C14 capacitor so that it is no longer connected to the board and check if there is audio. If there is then C14 is faulty, replace it

Tap a wire from earth to the A-GND terminal that the speaker is connected to and check if there is audio. If so then the C38 capacitor is faulty, replace it

Replace the C27 capacitor and check.

If still no good you may have to replace the U3 IC audio amp.

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Hi I know its been awhile but im also having this issue and Im a beginner so I have some questions you can hopefully answer if youre still around. My multimeter comes in tomorrow so i didnt test any connections but i switched the speaker and the head phone jacks with two known working and good parts and still nothing. When i bought the gameboy it appeared that someone put a new speaker in and did a horrible job. The wires werent in the through holes but just soldered on top of the pad and one of the wires was soldered to one of the speaker pads AND on of the headphone jack pads (assuming it was an accident)

I have several questions - by earth do you mean a ground? and where is the SW test point? How would i unsolder only one side of the c14 capacitor its very tiny? and by taping a wire do you just mean running a wire from a normal ground to the A-GND? and where is the A-GND? Im sorry if this is alot to explain im very new to this.

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@garywastaken

Earth = Ground The terms are interchangeable and mean exactly the same thing.

C14 would have to be removed if is is an smd component (surface mount device) and then you could test it "out of circuit" with a Ohmmeter and it should test OL or open circuit as capacitors are open circuit to DC but not to AC. Audio signals are effectively an AC signal and not a DC signal

If you solder a wire from the side of C38 that goes to the earth connection NOT the side that goes to the speaker terminal (A-GND) and then solder the other end it to the AGND speaker terminal i.e it bypasses the capacitor - side that would normally connect to C38) and then try for audio and it works then the C38 capacitor is faulty because it should pass the AC audio signal that comes from the audio amp, through the speaker and then to gnd. You could always simply short out the C38 capacitor and then also try it.

I think that AGND is the manufacturer's schematic reference for the ground side of the speaker AGND = Audio ground perhaps idk.

The capacitor is only used to isolate the earth which would go through the speaker to the amp for DC currents which may affect the back end of the amp.

If still no good connect one test probe from your Ohmmeter between pin 3 of U3 IC chip and the other meter probe to the speaker terminals one at a time you should see continuity to and then through the speaker. Always disconnect the power from the board when using an Ohmmeter.

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Okay thanks im gonna just try replacing C38 and see how it goes and let you know thank you so much for the quick answer!

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