Chosen Solution
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.
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.
(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.
