PCE GT - Earphone Sound Issue

brettlee · 10/31/2008, 08:16 AM

Hi fellow PCE freaks,

I just acquired a GT from eBay. It's my first ever PC Engine!! Always wanted one as a kid. Looks sweet. Everything is in working order. The speaker is also loud. However when I plugged in an earphone, the right channel seem very soft compared to the left. Is there a problem? Or can it be fixed? Thanks guys.

nat · 10/31/2008, 10:46 AM

Someone did the GT "audio fix" on this but only repaired the left channel (the channel that affects the speaker), apparently.

You have two options-- put a shunt in that jumps the two channels together, or, for a proper fix you can replace the caps that affect the right channel.

brettlee · 10/31/2008, 12:52 PM

Quote from: nat on 10/31/2008, 10:46 AMSomeone did the GT "audio fix" on this but only repaired the left channel (the channel that affects the speaker), apparently.

You have two options-- put a shunt in that jumps the two channels together, or, for a proper fix you can replace the caps that affect the right channel.

Hey Nat,

Thanks for the reply. I've read that somewhere in this forum. Hmm.. since I don't have experience in soldering, I think I'll just let it be for now.

I noticed the GT heats up quite abit after an hour's play. Will this affect the components in the long run? Geez.. I'm quite paranoia after hearing so many failed GT stories..

Duo_R · 11/18/2008, 06:41 AM

Nat,

do you know which cap affects the left or right channels? I have a unit now that has the issue. Would it be one of these caps (besides the circled normally fixes the issue cap)?

thanks,

Duo-R

Quote from: nat on 10/31/2008, 10:46 AMSomeone did the GT "audio fix" on this but only repaired the left channel (the channel that affects the speaker), apparently.

You have two options-- put a shunt in that jumps the two channels together, or, for a proper fix you can replace the caps that affect the right channel.

agt_dale_cooper · 11/20/2008, 04:58 PM

Replace all four of them, don't bother mucking about with one or two....I substituted 47uF for the two 33s (Nat mentioned this results in louder sound), and straight replaced the two 100s. I haven't found subminis that will mount in that location yet...RRR...had to mount them down the side.

nat · 11/20/2008, 08:31 PM

agent speaks the truth. Just replace 'em all. Use 47ufs in place of the 33's for a slight boost in overall volume. (47s are more common anyway.)

blueraven · 11/20/2008, 08:33 PM

Quote from: agt_dale_cooper on 11/20/2008, 04:58 PMReplace all four of them, don't bother mucking about with one or two....I substituted 47uF for the two 33s (Nat mentioned this results in louder sound), and straight replaced the two 100s. I haven't found subminis that will mount in that location yet...RRR...had to mount them down the side.

I'm going to have to agree that if the console is open, just replace all 4.

brettlee · 11/21/2008, 01:46 AM

Wowie. Thanks for the replies here guys. I'm not in favour of opening up my GT (at the moment) let alone do some soldering on it! It doesn't seem so bad listening to only one channel with headphones

Anyhow I really appreciate and respect those who have shared their hardware knowledge for fixing this problem! Maybe not now but in the future, I will eventually have to get those caps replaced myself..

THANKS!

Duo_R · 11/21/2008, 04:56 AM

47uf is a great substitute for the 33's, since I have plenty of those "in stock." Thanks for the info. Should there be a sticker on the repaired units that says:

"Warning! Listening to your PC Engine GT with 47uf caps installed could result in hearing loss"

Platinumfungi · 11/22/2008, 11:13 AM

Quote from: nat on 11/20/2008, 08:31 PMUse 47ufs in place of the 33's for a slight boost in overall volume.

Really? That's awesome news. I'll add that info to that chart I put up here awhile back.

Duo_R · 11/23/2008, 04:52 AM

I found the cap today that was bad on one of the sound channels. The small 33uf to the left of the cap that is circiled fixed one of the sound channels that were lower than the other. I imagine the two 33uf's are associated with each sound channel.

Quote from: Duo_R on 11/18/2008, 06:41 AMNat,

do you know which cap affects the left or right channels? I have a unit now that has the issue. Would it be one of these caps (besides the circled normally fixes the issue cap)?

thanks,

Duo-R

Quote from: nat on 10/31/2008, 10:46 AMSomeone did the GT "audio fix" on this but only repaired the left channel (the channel that affects the speaker), apparently.

You have two options-- put a shunt in that jumps the two channels together, or, for a proper fix you can replace the caps that affect the right channel.

nat · 11/23/2008, 05:36 AM

Yes, these have already been identified as culprits for the bad sound issue... These are the 33's I suggest replacing with 47's.

Duo_R · 11/23/2008, 06:05 AM

Thanks nat and others for reply. I had two units exactly described as the first post but now have full stereo with the 4 audio caps replaced.

I was really trying to narrow it down to the main cap that fixes aud, and just the cap related to sound channel. I guess doing the 4 cap combo is the way to go.

brettlee · 11/29/2008, 04:33 PM

Hey guys. Today I decided to open up my GT and clean its casing and I noticed that there was one leaking cap that is located between the vol and brightness dial as seen in the pic below.

Any idea what that cap affects? So far I've only got the low right earphone vol issue with this unit. Others work perfect. However, Street fighter II Hucard which was working all the time whenever I inserted it is now not booting. But I guess that could be the HU card cause I tried others and they all work.

nat · 11/29/2008, 09:23 PM

I haven't figured out what that cap does, but in nearly every case I've seen it looks just as nasty as yours. I usually always replace it when I'm in there, but on the other hand, it doesn't seem to affect anything one way or the other. I'm sure it's not part of the sound circuit. Beyond that.... Your guess is as good as mine.

brettlee · 11/30/2008, 12:19 AM

Hi Nat, appreciate your feedback on this. Yeah, I can't help but noticing that that's the only caps that's gone bad.. Anyhow I'll leave it for now. Does leaving bad caps on the board affect other circuitry? Just abit worried what harm it'll cause in the long run...

Also, when you turn on the GT/Express, how long it takes before you see the game's boot screen ? Mine when i first power on will be all white screen, followed by a 1 second delay and then only the game screen shows.. I wonder its normal. I have to note that mine's modded with a JP/US switch.

nat · 11/30/2008, 04:04 AM

That's normal...

Leaving bad caps won't affect other circuitry unless that brown goo leaks onto the board and starts touching other traces/caps. It's conductive and can cause issues if it does, essentially a short circuit. If it's isolated to the cap itself (as in your case), you have nothing to worry about except the cap itself failing completely.

brettlee · 11/30/2008, 04:29 AM

Phew.. What a relief. A little update, turns out that the SFII:CE HUcard was dirty (even though the contacts looked shiny at first, a transparent gummy grime was the culprit) I took some Q tips with rubbing alcohol and wiped those grime out and it's now working like new again.. Double relief!!!

Duo_R · 11/30/2008, 05:01 AM

isn't there a wire on the other side of the PCB connected to this cap that you were wondering about?

Quote from: brettlee on 11/29/2008, 04:33 PMHey guys. Today I decided to open up my GT and clean its casing and I noticed that there was one leaking cap that is located between the vol and brightness dial as seen in the pic below.

Any idea what that cap affects? So far I've only got the low right earphone vol issue with this unit. Others work perfect. However, Street fighter II Hucard which was working all the time whenever I inserted it is now not booting. But I guess that could be the HU card cause I tried others and they all work.

brettlee · 11/30/2008, 06:43 AM

Hi Duo_R, that's the blue/red wire that takes power from the battery compartment.

agt_dale_cooper · 11/30/2008, 10:22 AM

Damn, that cap is NASTY looking...haven't seen anything close to that in all my recent exploits.
Be sure to CLEAN THE BOARD in that vicinity after you've removed that leaked-all-the-place-looking mess...
Good luck!!

brettlee · 12/25/2008, 11:27 PM

Hey guys, remember I was complaining about this earphone issue? Well... I HAVE FIXED IT!! I took the plunge and decided to try the surgery out myself (with big hopes that I won't screw anything up!) Actually I was planning to perform a surgery on my other Sega White GG which had a display problem, so I decided to try this simple operation for the GT first for starters (isn't any easier than I thought!)

So, here's how my sound caps looked like before the operation :

As you can see, someone had already replaced a pair of 100uF and 33uF. I'm guessing that these pair corresponds to the Left audio channel which also sends out signal to the internal speaker.

With that in mind, I thought all I needed to do to restore the Right channel was to replace the other 33uF. I tried it with the remote mounting technique (it was my very first attempt doing it!!! I was so scared I'd fried something) Luckily it was a success, but it didn't restore the Left channel's volume level. I did noticed that the Left channel had a slight humming sound, indicating that maybe the new replacement cap had already open up the channel, but the volume level was still very low.
So, I thought it could be the last cap standing that could be the big culprit to this whole mystery. And I went ahead and changed it. This time I tried soldering the cap on the pad itself.. Thank god it turned out well. The spot there is so tight.. And yeah, I almost burnt the headphone port and the 100uF cap next to it!!!

Here's the end result

It looked like a mess, I had to used tapes to shield the exposed 33uF caps, my bad for not trimming it shorter :p. The new 100uF cap is also installed.

Here is a pic of the culprits!

The headphone audio is now PERFECT!! I can know here SFII's intro music in STEREO with the headphones!!!! I just love when the tomtom rolls from the right to left.

Being a total newbie in electronics soldering, I think I'm quite proud with my work

I need more practise, and plan to get more of those mini DIY electronic kits in prep for my White GG operation.

Thanks for watching. Oh yeah, I'd like to say a BIG THANK YOU TO RED GHOST for his TurboExpress Total Caps Replacement Chart!! Please download this chart and save it for future reference!!!

brettlee · 12/25/2008, 11:31 PM

Quote from: agt_dale_cooper on 11/30/2008, 10:22 AMDamn, that cap is NASTY looking...haven't seen anything close to that in all my recent exploits.
Be sure to CLEAN THE BOARD in that vicinity after you've removed that leaked-all-the-place-looking mess...
Good luck!!

Oh yeah, before this whole 33 and 100 uF caps replacement went on, I replaced this 470uF cap first and didn't noticed any improvements to the audio. I'm still wondering what does this particular cap functions in the circuit. Since it's located near the dials. Could it be used by them? I also cleaned up the leaked electrolite juices with rubbing alcohol.. Uggghh...

Duo_R · 12/25/2008, 11:43 PM

as Nat has stated, just replace all the caps in the audio circuit. It simply is not worth replacing one or two at a time, just shotgun the sucker. I have replaced a batch of these and different caps in that circuit go bad. For 100% fix, replace all of them.

brettlee · 12/25/2008, 11:50 PM

Quote from: Duo_R on 12/25/2008, 11:43 PMas Nat has stated, just replace all the caps in the audio circuit. It simply is not worth replacing one or two at a time, just shotgun the sucker. I have replaced a batch of these and different caps in that circuit go bad. For 100% fix, replace all of them.

Yeah, my bad for not listening to him

Nyways lesson learned and will know what to do in the future

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PCE GT - Earphone Sound Issue