Author Topic: PC Engine GT - Speaker audio good but... Weaker than it used to be.  (Read 1420 times)

pipi

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Hi all,

My Pc Engine GT has a very long story.
It was recapped the first time by someone that produced a fair amount of damage to its motherboard but in the end "made it work".
After that many years passed and I've sent it to another modder to get RGBDRV mod. The result is frankly stunning.
The modder also suggested a full recap because of the not great job done previously (gorilla glue, pads ruined, etc).
In the end my Pc Engine is now working fine with a marvelous screen but the audio compartment is not as flawless and powerful as it used to be.

In earbuds I hear a hum, it could be related to RGBDRV mod.
If someone has a suggestion it would be great but it is something I can live with (using earbuds with a volume potentiometer makes it a LOT better).
The main problem is using the unit with its speaker...
Volume sounds...
A bit lower.
It is not super low but I remember my PC Engine shouting with marvelous bass and now it is just...
Loud but...
Decent, not great.

Am I dreaming or not?

I've read in the forum that some modders put 47uf capacitors for audio instead of the designed 33uf so it could be that maybe the 1st modder used the 47uf and the second put 33uf so I hear all this difference?
How can I test if everything is how it should be?

If I want to test functionality with 47uf I need to remove the current 33uf or I can put them connected together (or add a 14uf to the 33uf)?

Please forgive my ignorance and thanks for your time and help.

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #1 on: July 08, 2021, 06:40:50 PM »
Hi all,

Tonight I opened the unit and took some pictures about the current status, maybe someone can point out potential issues:
https://photos.app.goo.gl/Lmbur4rBHHnrmGr68

Thanks :)

Keith Courage

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #2 on: July 12, 2021, 08:09:23 AM »
I can't notice anything from the pics but your problem is either 1 of two things.

Either there is a bad trace for 1 of the 4 caps just behind the headphone port(2 100uf and 2 33uf)

or, the internals of your heaphone port have been damaged from being heated too much during the cap change. Years ago when I recapped my first Turbo Express I did that very thing. Had to replace the headphone port. 

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #3 on: March 17, 2022, 07:08:18 PM »
Hello and sorry for taking ages to reply to this post but life sometimes gets crazy and we have to put projects in the drawer for...
Too long :)

I am ready to get back in the fight and I totally want to fix my bad boy...
But I have 2 questions:
1) Can I connect the speaker directly to the caps in order to check if the volume pot is the issue or not? Where should I connect it?
2) in case the volume pot is faulty, where can I get a nice compatible part to change the earphone plug?

Thanks for your help, as always!
« Last Edit: March 18, 2022, 03:56:58 AM by pipi »

MasterofBiscuits

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #4 on: March 18, 2022, 04:42:26 PM »
How is the audio level when you adjust the volume pot? Does it change smoothly or is there a lot of crackling/ uneven change? If it sounds smooth then the pot is probably fine.

My concern would be the repair work around the audio caps - I would guess that perhaps one of these is not fuctioning in the circuit properly so you are only getting half the capacitance you need. I would suggest removing those caps, and all that solder and make sure everything is wired correctly. If you zoom this pic in, you can see what that area is supposed to look like with no caps in the way: https://i.imgur.com/bO65mVM.jpg
CC102 in particular looks suspicious to me.

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #5 on: September 26, 2022, 08:12:46 AM »
Hi all!

I am still fighting this horror.
I checked the capacitors using an enamel wire soldered on their feet and checking continuity one by one, seem OK.

I should man up and replace the earphone connector but I am scared to make mistakes...

Is it only anchored in 3 points?

Another weird question...
My earphone audio is LOUD AS HELL.
It really hurts if I cranck it to maximum...
I am thinking...
Could it be that somehow the speaker and the earphone got inverted?
If yes, how could this be possible?

Thanks :)

Keith Courage

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #6 on: September 27, 2022, 04:38:47 AM »
It's normal for the headphones to get crazy loud on these systems. However, they can get even louder if the headphone port doesn't do the switching correctly. So yes the speaker volume can get pumped through the headphone port and this is caused by a bad headphone port when the switching mechanism is damaged.

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #7 on: October 01, 2022, 06:50:18 PM »
I think you are right and it is the time I take courage and replace this part...
Can you kindly suggest where I can get a good quality and compatible one?

Thanks :)

Keith Courage

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #8 on: October 02, 2022, 08:17:00 PM »
Pretty sure console5 has them. Same as the Sega game gear headphone jack.

I should mention that you will have to slightly drill out the headphone opening on the case of the express ever so slightly for any headphone port replacement. All the replacement Jacks I have found are just a little bit larger for the opening.

MasterofBiscuits

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #9 on: October 03, 2022, 04:59:07 PM »
I think you are right and it is the time I take courage and replace this part...
Can you kindly suggest where I can get a good quality and compatible one?

Thanks :)

https://www.aliexpress.com/item/32722775267.html

These are the ones you need, PJ-307D. As Keith says the 'neck' is slightly larger than the original so will need some modification - personally I prefer to file the socket rather than the console case.

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #10 on: October 05, 2022, 05:19:34 PM »
Deeply thanks to both, parts ordered!

You guys are awesome :)

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #11 on: November 21, 2022, 04:28:10 AM »
Dear all, a small update from the field.

Parts were in for a bit but I was just scared to death.

Today I took action, put all the time, patience and care in the world.
The part was just STUCK AS HELL.
I see that connections 10 and 2, on the bottom part of the board, had lifted pads.

Do you happen to know how i can test those connections before replacing the parts and maybe patch them with enamel wire?
Is this beyond salvation?

Thanks for your time and help.



« Last Edit: November 23, 2022, 05:47:23 AM by pipi »

pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #12 on: November 21, 2022, 03:05:51 PM »
Latest news:
The speaker was faulty, ruined by the guy that did the rgbdrv mod.
I want to explode  :boom:

Long story short there was no need to remove the 3.5 plug.
I have replaced the speaker with a 8ohm 2 watt.
Sadly still no sound, probably the damage made removing the 3.5mm :(

I am not done for the day...
I tried the connectors from aliexpress suggested by master of biscuit and also an original game gear connector.

The game gear one has a lot less pins but both provide the same result: loud earbuds, zero speaker.
« Last Edit: November 21, 2022, 06:03:49 PM by pipi »

MasterofBiscuits

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #13 on: November 25, 2022, 07:40:45 AM »
If you have sound in the headphones but not in the speaker it must be either the switching part of the headphone socket (which is the 3 pins at the back side of it) or the connection to the speaker.

That board is kind of a mess with bits of solder and flux, you need to clean all of that up, stray bits of solder can cause shorts and other damage. I've highlighted some parts of concern, get some wick and clean these areas up and make sure nothing is broken or shorting to other parts.

To remove the headphone socket you need either hot air or some low melt solder (my preferred method) - removing just with regular solder and a soldering iron is not ideal when there's that many pins, no wonder you had trouble.



pipi

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Re: PC Engine GT - Speaker audio good but... Weaker than it used to be.
« Reply #14 on: November 26, 2022, 10:40:45 AM »
Hi Master and hi to all readers...

Problem is solved!
It was the flat connecting the controller board XD

I replaced the 3.5mm connector for nothing but I am deeply happy it is finally fixed.

Thanks for all the help and all the learning to you and the almighty Keith Courage and a special mention to @PointerFunction (twitter handle) that opened up his PCE GT and checked continuity in order to give me troubleshooting material.

Love this forum and the people contributing to it, you rock!
« Last Edit: November 29, 2022, 06:03:35 AM by pipi »