NEO-MVH 4 Slot, Crackling sound

Sypth

Mr. Big's Thug
Joined
Nov 14, 2010
Posts
206
Did the usual and replaced all the caps in the sound section. Went as far as replacing and socketing a few of the amps, dac, and ha13001. Still getting the same results. Anyone have any ideas what this might be caused by? It seems to be a thermal issue, because if I let it sit for a bit, it'll start up fine, but within 10-15 seconds it'll start crackling again.

Playing it on a mono cab, so it does sound already a little strange, but you can hear what I'm talking about in this video.

https://drive.google.com/file/d/0B23xUYIS4zgCZkJremg4LTNNMUE/view?usp=drivesdk

Here's the board

 

arcade game

Galford's Armourer
10 Year Member
Joined
Apr 28, 2012
Posts
466
Did the usual and replaced all the caps in the sound section. Went as far as replacing and socketing a few of the amps, dac, and ha13001. Still getting the same results. Anyone have any ideas what this might be caused by? It seems to be a thermal issue, because if I let it sit for a bit, it'll start up fine, but within 10-15 seconds it'll start crackling again.

Playing it on a mono cab, so it does sound already a little strange, but you can hear what I'm talking about in this video.

https://drive.google.com/file/d/0B23xUYIS4zgCZkJremg4LTNNMUE/view?usp=drivesdk

Here's the board

Had the same problem on a 6slot I recently got
Did a cap kit on sound section and problem didn't go away;(
Turns out it was the actual volume slider pot.replace it with one from a parts board and it's working like new again
i hope that helps
 

Sypth

Mr. Big's Thug
Joined
Nov 14, 2010
Posts
206
Huh, I cleaned it fairly well, but I'll try swapping it out.
 

Sypth

Mr. Big's Thug
Joined
Nov 14, 2010
Posts
206
Swapped out the volume slider. Still no go, thinking about tackling the ym2610.
 

drmadd220

n00b
Joined
Feb 8, 2006
Posts
43
I have the same problem with one of my 4-slot boards. I'll be interested what you find out.
 

Sypth

Mr. Big's Thug
Joined
Nov 14, 2010
Posts
206
Put a new 64 pin socket in and a YM2610. Fixed my issue.
 

drmadd220

n00b
Joined
Feb 8, 2006
Posts
43
I replaced my YM2610 this past weekend and the problem still exists. Already did a cap kit on it first but that didn't help.
 

BIG BEAR

SHOCKbox Developer,
20 Year Member
Joined
Dec 14, 2001
Posts
8,230
Your going to have to check the traces rumming from the YM2610 .On an MV2 I had bad traces at pins 10-13 as they run up toward the battery area and over to the slot(s) area.
I replaced my YM2610 this past weekend and the problem still exists. Already did a cap kit on it first but that didn't help.
 

GadgetUK

Ace Ghost Pilot
Joined
Sep 27, 2013
Posts
1,323
I think big bear is probably right - possibly an intermittant trace. I would be tempted to clarify where the sound issue is first, ie. is it all audio (as it sounds to me from that video), or is it PCM, FM, or both etc. If you run the sound test in diagnostics, how does that tone sound (for left, right, center). If there's distortion there I would be thinking about the op amp and amp section. I would also check the headphone output (that 4 pin white connector) - you could wire up a 3.5mm socket to that 4 pin connector and test that way, or do what I did and isolate the pins on the 3.5mm socket above it and join some wires up for left and right to the white connector underneath. If both headphone and main speaker outputs are still distorted you can look back a stage as both having a common fault indicates its the initial pre-amps or the output into the pre-amps. The other benefit of testing the headphone output is to work out if its left or right side related (or both). It could end up something as simple as a bad 12v line on your PSU?!? And if you're only testing the amplified mono output that could confuse things.
 

drmadd220

n00b
Joined
Feb 8, 2006
Posts
43
Hey Guys thanks for the help. Here is what was happening, startup intro would play sound fine, then had metal slug X installed and anytime there was an explosion the sound would be crackly but music in game was fine. Also put in Aero fighters 2 and again any explosions would be crackly but the rest of the music would play fine. I did the test tones, and all played normal and came out the correct speakers. I also tested the headphone jack (before I swapped out the YM2610) and heard the same crackling as on the speakers. So I decided to load up metal slug X on the neoSD (after reading BIG BEAR and GadgetUK's responses) and see what happens. That sound played fine. So I installed the Aero Fighters 2 cart that I also had problems with and it played fine. I reinstalled the metal slug X cart and it still has issues. So replacing the YM2610 chip did fix my sound issue on the motherboard but I guess the metal slug X cart also has an issue. Well one problem fixed and one to go.
 
Top