Terrible hissing after changing capacitors

[Peeteris]

Hi!

I've decied to change capacitors on my IPS modded GBA. Before changing caps, it was noisy, but not out of ordinary for GBA. Thought that changing to new Panasonic caps wouldn't hurt and maybe would make buzzing less noticeable.

Somehow, after I changed CP1, CP2, CP3 and CP4, it got unbelievably worse. Now it's hissing and screetching and just making unbearable noises at any volume (although noises do get louder on max volume).

Checked everything - as fas as I can see I haven't knocked anything off, volume potentiometer is clean, power switch cleaned thoroughly, tried to add 220uF cap to amp chip. Nothing made any difference.

Really confused here, no ideas left, what's wrong.
Any help appreciated! Check out picture kf motherboard and video attached.

 

[tech3475]

Have a look at the solder on the amp, the top left seems a bit off.

 

[Peeteris]

Have a look at the solder on the amp, the top left seems a bit off.

That's the lightning, pads are not bridged and are connected to the motherboard.

Also, if I don't attach display, audio is clean and there isn't any noise.

Just strange that with old caps there wasn't such a problem. Maybe my caps aren't correct values?

 

[tech3475]

That's the lightning, pads are not bridged and are connected to the motherboard.

Also, if I don't attach display, audio is clean and there isn't any noise.

Just strange that with old caps there wasn't such a problem. Maybe my caps aren't correct values?

I've been looking at the caps, uf seems correct but can't tell the voltage.

Did you get them from a reputable dealer?

Have you tested with the original display if you can?

 

[Peeteris]

I've been looking at the caps, uf seems correct but can't tell the voltage.

Did you get them from a reputable dealer?

Have you tested with the original display if you can?

Yes, got from the most reputable local store.

For CP1 and CP4 it's Panasonic EEEFPJ101UAR 100uF 6.3V
For CP2 it's Panasonic EEEFT1V101AP 100uF 35V
For CP3 it's Panasonic EEEFK1C471GP 470uF 16V

 

[Sono]

I have actually knocked off a capacitor on my GBA SP, and I had bad noise even with IPS and stock screen.

I have replaced the capacitor going into the amplifier VREF (check gekkio schematic, C21 on my AGS), and that made the noise quieter than it was before.
Seems like for you, it's C39 that goes into the VREF pin.

I have stolen one of the the LCD high voltage capacitors from a blown DS Lite, and now the noise is even quieter than before knocking it off.

 

[Peeteris]

I've been looking at the caps, uf seems correct but can't tell the voltage.

Did you get them from a reputable dealer?

Have you tested with the original display if you can?

It's totally silent with original display, that's a relief.
I have installed 720*480 Drop in 3.0" V5 Laminated GBA IPS

 

[tech3475]

It's totally silent with original display, that's a relief.
I have installed 720*480 Drop in 3.0" V5 Laminated GBA IPS

Did it still sound that way even with the backlight off on the replacement display? I'm wondering if there's something about the mod causing the issue e.g. a faulty display, drawing too much current, etc.

Is there a chance the display is shorting against something?

Note: I've never dealt with this kind of mod myself

 

[Sakitoshi]

i'm no expert, but those caps are rated differently than the originals.
based on what i could find, the 470 uF cap says CFK. that indicates it's rated for 16v while the original is rated for 6.3v.
didn't check the rest, but that would explain why those caps are noisier.

but outside of that.
changing the caps helped with supercard compatibility?
i'm still curious about why it doesn't work for you even with original firmware.

 

[tech3475]

i'm no expert, but those caps are rated differently than the originals.
based on what i could find, the 470 uF cap says CFK. that indicates it's rated for 16v while the original is rated for 6.3v.
didn't check the rest, but that would explain why those caps are noisier.

but outside of that.
changing the caps helped with supercard compatibility?
i'm still curious about why it doesn't work for you even with original firmware.

I always thought having higher voltages didn't matter so long as the uf was correct?

Also, could you please tell me how you know the voltage from the letters? I had a quick look last night but struggled to find out what they meant.

 

[Peeteris]

Did it still sound that way even with the backlight off on the replacement display? I'm wondering if there's something about the mod causing the issue e.g. a faulty display, drawing too much current, etc.

Is there a chance the display is shorting against something?

Note: I've never dealt with this kind of mod myself

With old caps display didn't make such noise.
Yes, with new caps if I make screen brighter, noise gets louder and if dimmer - noise gets lower.

Nothing changed about display, nothing shorts AFAIK.

Post automatically merged: Apr 7, 2025

i'm no expert, but those caps are rated differently than the originals.
based on what i could find, the 470 uF cap says CFK. that indicates it's rated for 16v while the original is rated for 6.3v.
didn't check the rest, but that would explain why those caps are noisier.

but outside of that.
changing the caps helped with supercard compatibility?
i'm still curious about why it doesn't work for you even with original firmware.

No, changing caps didn't help with Supercard compatibility at all. Supercard still behaving the same, same glitches etc.
Anyone can confirm that biger voltage caps could impact this? Always thought that the only donwside to bigger voltage caps is the size usually, but they shoud, behave the same?
Also, all these are pretty pricy, low ESR caps. Could low ESR which makes caps more power-efficient and less heating also influence something?

Post automatically merged: Apr 7, 2025

Additionally, tried every trick that's written here: https://www.retrosix.wiki/dehum-dehiss-removing-noise-from-gba-audio

By this instruction (Over Current Noise) Tried adding 680uF cap to CP1, it made noise a bit lower, but not by much. 1000uF sounded the same as 680pF.

Not sure what to do as it's unplayable like this and I don't have old or even other new caps anymore.

 

[Sakitoshi]

as i said, i'm no expert.
but as far as i know, the rating of the cap affects which noise frequency it filters. it is better to ask someone that knows about it.

Also, could you please tell me how you know the voltage from the letters? I had a quick look last night but struggled to find out what they meant.

i just searched until i got the data sheet of caps with the letters and compared to the writings in caps of a stock gba.

 

[Peeteris]

Maybe someone can suggest good capacitors that will work for recap?
For example, these are from Handheldlegends page, but I can't seem to find any information about these caps in the picture.
Can't really purchase from them as shipping costs 3x more than caps,

 

[moon_rabbit]

How about trying to replace the AA batteries? Panasonic capacitors are reliable components.
What kind of AA batteries are you using? Try using high-quality rechargeable ones like Eneloop Pro.

 

[Peeteris]

How about trying to replace the AA batteries? Panasonic capacitors are reliable components.
What kind of AA batteries are you using? Try using high-quality rechargeable ones like Eneloop Pro.

Yes, I'm using eneloop batteries.
Still not good, if old, smelly and dry capacitors didn't produce such noise and Panasonic caps do.

I think it might be because I bought more expensive low ESR caps, but maybe GBA expects more resistance from caps.

 

[Peeteris]

Update:
Yes, the problem was better quality, low ESR capacitors.

When buying caps for GBA, be sure to buy cheaper, standart capacitors with higher resistance.