PCE Duo-R hum

[Amerika]

So, this is going to be a shot in the dark.  But I have already eliminated some potential causes.

MY PCE Duo-R (RGB modded...newer Doujindance mod) has a hum that happens with some games.  I am using the latest Turbo Everdrive.  The games that cause a hum during the pause menus are:

Ninja Spirit
Impossimole
Bonk's Adventure
Bonk's Revenge (oddly, Bonk 3 does not)
Image Fight (but only directly after a death but not during a pause)

Also, if I use the 240p test ROM and I run the horizontal or vertical line scroll test, I get hums but they are both different pitches with one being quite a bit higher pitched than the other.  But if I do the normal scroll test (looks like the Sonic Green Hills Zone background) there is no hum.

Also, with games like Impossimole and the Bonk's, it sounds like the last note is what is always repeated and the hum's pitch is based on that.

I've randomly tried tons and tons of games and most of them seem to not display the issue.

Things I have tried:

Changed power sources 3 times (using an genuine NEC power source that has been recapped)
My PCE has been fully recapped
I moved the RGB mod around to make sure it wasn't causing interference due to improper shielding near any components that might cause the hum.
I've changed RGB cables from the doujindance to a fully shielded retro-access cable
I get the same hum using composite
I've tried different ROMs
I've jiggled the RGB cable to see if it's a bad connection with the DIN (I guess those can cause issues...but not like this).

Sadly, I do not have any of the physical games that actually cause the problem.  I'm debating on buying Ninja Spirit since it's just freaking awesome and I love it but it's a bit expensive.  Even the Bonk games are a bit expensive even though they aren't exactly rare.

Has anybody heard of this or has a similar setup that could test those particular games?

Thanks!

[SignOfZeta]

How long have you had a PCE? I ask because none of these systems are quiet so I'd hate to have you tracking down an unfixable problem.

[Amerika]

How long have you had a PCE? I ask because none of these systems are quiet so I'd hate to have you tracking down an unfixable problem.

I've had it for not quite a year.  I've had another friend check their system, which is a core grafx 2 hooked up via an SSD3, and it does not have the same humming issue with those titles (or any humming at all).

I've read that some PCE's do hum, especially when the screen gets brighter, but that isn't the case with mine (and that issue is usually caused by an improperly shielded cable).  It's just certain games and the pitch/frequency seems to change based on the last note played a lot of times.  Or in the case of the 240p test, the horizontal and vertical tests produce different hums.

[SignOfZeta]

I don't know much about flash stuff but every PCE I've ever used is squeaker and squaukier than other machines. They can't produce silence from my experience and yeah the game does matter. I can't remember which PCE have the "fixed" (not really) soundchip or if it's related to this. I think the Core 2 is one of the updated ones though so...I'm still not sure we aren't taking about regular PCE noise.

When you soft reset a game sometimes, as you sort of are saying, the last sound gets stuck on slightly. Hard power cycles fix it. Ninja Spirit in particular does this, IIRC. However because flash carts usually use a multi game loader app I'm not really sure how soft resetting is affected. It could be a related thing to what I'm familiar with or not.

[Amerika]

I don't know much about flash stuff but every PCE I've ever used is squeaker and squaukier than other machines. They can't produce silence from my experience and yeah the game does matter. I can't remember which PCE have the "fixed" (not really) soundchip or if it's related to this. I think the Core 2 is one of the updated ones though so...I'm still not sure we aren't taking about regular PCE noise.

When you soft reset a game sometimes, as you sort of are saying, the last sound gets stuck on slightly. Hard power cycles fix it. Ninja Spirit in particular does this, IIRC. However because flash carts usually use a multi game loader app I'm not really sure how soft resetting is affected. It could be a related thing to what I'm familiar with or not.

Well, the crazy thing is that tons of games are entirely silent.  Zero hum/noise/anything.  It's perfect.  But the games I listed, and I'm sure many more, seem to have this issue or at least partially has this issue.  I'd like to fix it if possible but I'm also curious from a technical/troubleshooting standpoint as to what could cause something like this and if it's actually common or this issue is specific to my Duo-R and/or my Turbo Everdrive.  I should probably pick up a copy of one of those games I listed and try to rule out the turbo everdrive being the culprit.

[nopepper]

I just tried Ninja Spirit both with the original chip and on an ED 1.1 in a black gonk of doujindance-death Duo R through a PVM and a receiver. Also tested it on the ED in a Coregrafx 1/blue through a Sony Wega using the set's speakers (don't have the PCE version, so can't try the og there), and they all have the hum when you stop the music from the sound test. I then tried Image Fight, both original and ED in both systems, and also heard the hum after a death, just as you described.

As Zeta indicated, a lot of games have that hum, where the last note gets "stuck" after a reset, transition, etc. AFAIK, this is just normal and just an idiosyncrasy of the system. I'm not sure if there are any differences between the Coregrafx 1 and 2, but at least on mine, that hum is clearly there.

[JoeQuaker]

Yeah, I would agree with nopepper. This sounds like common quirks of the system in my opinion.

[Amerika]

I just tried Ninja Spirit both with the original chip and on an ED 1.1 in a black gonk of doujindance-death Duo R through a PVM and a receiver. Also tested it on the ED in a Coregrafx 1/blue through a Sony Wega using the set's speakers (don't have the PCE version, so can't try the og there), and they all have the hum when you stop the music from the sound test. I then tried Image Fight, both original and ED in both systems, and also heard the hum after a death, just as you described.

As Zeta indicated, a lot of games have that hum, where the last note gets "stuck" after a reset, transition, etc. AFAIK, this is just normal and just an idiosyncrasy of the system. I'm not sure if there are any differences between the Coregrafx 1 and 2, but at least on mine, that hum is clearly there.

Thank you very much for confirming that for me.  A friend checked and said he couldn't hear anything with Ninja Spirit but could hear the hums with the 240p vertical/horizontal scroll tests.  His sound setup, I believe, goes through a receiver so it might be filtered out.  Or maybe it's louder with some systems than others.  Or maybe he's part deaf haha.

I seriously appreciate the assist in testing this and everyone else's input.  Now, I wonder why this is something that exists with the PCE and if there is a way to suppress it.  It sounds like a coding issue where they didn't properly terminate the music/last sound produced and it might be common as it is due to a lot of those devs using the same SDK's.  Maybe I'll look into a speaker setup that might filter out high frequencies like that.  I'm currently just using the speakers on my WEGA.

[NightWolve]

I dunno if this is similar to the standard hum you hear with a TurboExpress which is more pronounced when you use headphones. Our tech guru TheSteve actually solved this by using tantalum capacitors. If you don't wanna totally use those in a full capacitor replacement job you just need to target the 4 capacitors related to power and you can use regular electrolytic caps for the rest of the PCB.

That's what I remember from my discussions with him about it, but yeah, just concerning the TurboExpress, I don't remember a hum problem for my consoles.

[thesteve]

on the express its power hum, but thats not the OP issue
he is having SCART hum which has to do with the current running through the grounds on the SCART cable
there are a few ways to reduce it (mostly shorter cables or larger wires) but you wont completely eliminate it especially on bright screens.
a dark screen will have little hum due to the low image current

[nopepper]

I don't think the issue is specific to SCART, as I think the symptoms the OP described (and that I corroborated) are more akin to the last note "sticking" when a previously played note is stopped into what you would expect to be silence. If you go into the Ninja Spirit sound test, turn the volume up, start playing a song, then press II to stop, you should hear what is being discussed here. This happens in my RGB modded Duo R through SCART, as well as in my virgin Coregrafx through composite through different TVs and speakers.

Image Fight (coincidentally, another Irem game) exhibits the same behavior and can easily be heard through the sound test as well.

[thesteve]

im not saying that doesnt happen, but my impression was it was image related and the OP did specify it was an RGB modded system
this can easily be checked by using composite instead