Forums

Hi everyone.

I've just installed one of viletim's FM boards and it currently sounds terrible. I'm hoping someone has experienced this before or knows whats wrong.

The FM board is the latest version, 2.2.

The console is a SMS PAL VA3.

I have followed the instructions as per his site, removing C62 and wiring the red to positive and white to negative, and grounding the shield wire.

Video:

Should sound like this:

I've tried multiple games - both genuine copies and ROMs on a Master Everdrive - they all give the same problems where its distorted and sounds like there are channels missing.

PSG still works fine.

There's not much that can go wrong with this install, so I'm out of ideas, any help would be appreciated.

Thanks

Crap... That's a problem...

Put the capacitor that you pulled out back in between the red wire and the motherboard. I'm pretty sure that will fix it.

Why do you have a fan in there? The voltage regulator is supposed to run hot, it's not an issue. The fan will only provide unnecessary noise. :-)

Trolleri wrote

Why do you have a fan in there? The voltage regulator is supposed to run hot, it's not an issue. The fan will only provide unnecessary noise. :-)

Yeah seriously? LOL

viletim wrote

Crap... That's a problem...

Put the capacitor that you pulled out back in between the red wire and the motherboard. I'm pretty sure that will fix it.

Thanks for the suggestion viletim.

Adding the cap back in has changed the sound properties, but unfortunately has not improved on the initial problems.

It still sounds like there are parts missing, and still has random glitch moments like in the first video I posted.

I purchase a lot of YM2413 for my FM Power Base Converters. While I cannot really speak for this module's FM chip, I will point out that I scrap roughly 15% of the chips I purchase mostly for two reasons:

1 - no sound output at all
2 - garbled or wrong sounding instruments (something missing drum channels too)

In my experience, and maybe viletim can comment on his experiences as well, these chips are notorious for being deffective.

I posted an unlisted youtube video of a few bad chips:

Oddly enough we both tested with Double Dragon!

You should sell them at a premium price as "pre-circuit-bent" :)

I thought viletim had found a lot are fake (with the quality control that implies).

Maxim wrote

You should sell them at a premium price as "pre-circuit-bent" :)

Haha! You're not the first one to tell me that!

Edit: I actually shipped many of them back to the seller because they "claim" that all their stock is 100% tested and operational - bs.

unhuman wrote

viletim wrote

Crap... That's a problem...

Put the capacitor that you pulled out back in between the red wire and the motherboard. I'm pretty sure that will fix it.

Thanks for the suggestion viletim.

Adding the cap back in has changed the sound properties, but unfortunately has not improved on the initial problems.

It still sounds like there are parts missing, and still has random glitch moments like in the first video I posted.

Hi...long time lurker. First time poster.

I bought one of these first run new revisions too. I got to installing it the other night and had the exact same problem you did. Apparently there's a flaw in Tim's new design and it is missing the sound output cap on the board. You can make it work but you'll need the modify the install instructions a little.

Remove the specified capacitor (varies by board/region revision) and solder the white wire in to the positive side of the board (my solder pad broke off so I had to solder directly to pin 10 of the VDP but it's the same thing). Next, solder the red wire to the negative leg of the capacitor (striped side) and solder the positive leg of the capacitor to the negative side of the board. Then solder your ground wire to a ground and you'll be good to go. Awesome sound and all!

I'd like to thank Tim for his immediate response to my cries for help! A small design oversight that has a pretty easy fix.

I don't guarantee that this will work for all revision of SMS but it worked well for my original NTSC SMS.

Thanks,

Frank

edit: Looking at the install instructions for all the different board revisions it seems that the red and white wires change to different sides of the board (+ or - side of cap). I would guess that if you follow the instructions as normal for your particular SMS and install the capacitor with the negative leg to the red wire and the positive leg to the board (which ever position the instructions tell you) you'll be fine.

yimg-1130908088-1-1638007532.jpg (3.27 MB)

I installed a v2.2 FM module, a few days ago, in my original NTSC Master System (removing C49) and had no issues. As far as I can tell, it sounds correct.

I can't post links yet but you can search YouTube for video TQq6z-gAXDQ

Either my board is fixed or the problem only occurs on some variations of the MS and the issue is unique to the point where the capacitor is pulled and the audio is reinserted.

When did you order your board? Mine shipped out on Feb 19 2015.

Edit: One more thing. Are you sure that the polarity on cap C37 isn't backwards?

Author	Message
unhuman Joined: 14 Jul 2009 Posts: 9 Location: New Zealand	FM Mod Sound Issues Posted: Sun Mar 01, 2015 1:33 am
	Hi everyone. I've just installed one of viletim's FM boards and it currently sounds terrible. I'm hoping someone has experienced this before or knows whats wrong. The FM board is the latest version, 2.2. The console is a SMS PAL VA3. I have followed the instructions as per his site, removing C62 and wiring the red to positive and white to negative, and grounding the shield wire. Video: Should sound like this: I've tried multiple games - both genuine copies and ROMs on a Master Everdrive - they all give the same problems where its distorted and sounds like there are channels missing. PSG still works fine. There's not much that can go wrong with this install, so I'm out of ideas, any help would be appreciated. Thanks

viletim Joined: 24 Sep 2006 Posts: 191 Location: Sydney, Australia	Posted: Mon Mar 02, 2015 2:34 pm
	Crap... That's a problem... Put the capacitor that you pulled out back in between the red wire and the motherboard. I'm pretty sure that will fix it.

Trolleri Joined: 11 Feb 2015 Posts: 17	Posted: Mon Mar 02, 2015 7:26 pm
Trolleri Joined: 11 Feb 2015 Posts: 17	Why do you have a fan in there? The voltage regulator is supposed to run hot, it's not an issue. The fan will only provide unnecessary noise. :-)

ApolloBoy Joined: 30 Jan 2007 Posts: 317 Location: San Jose, CA	Posted: Mon Mar 02, 2015 7:38 pm
	Trolleri wrote Why do you have a fan in there? The voltage regulator is supposed to run hot, it's not an issue. The fan will only provide unnecessary noise. :-) Yeah seriously? LOL

unhuman Joined: 14 Jul 2009 Posts: 9 Location: New Zealand	Posted: Fri Mar 06, 2015 7:26 am
	viletim wrote Crap... That's a problem... Put the capacitor that you pulled out back in between the red wire and the motherboard. I'm pretty sure that will fix it. Thanks for the suggestion viletim. Adding the cap back in has changed the sound properties, but unfortunately has not improved on the initial problems. It still sounds like there are parts missing, and still has random glitch moments like in the first video I posted.

db-electronics Joined: 06 Dec 2013 Posts: 335 Location: Canada	Posted: Fri Mar 06, 2015 7:30 pm
	I purchase a lot of YM2413 for my FM Power Base Converters. While I cannot really speak for this module's FM chip, I will point out that I scrap roughly 15% of the chips I purchase mostly for two reasons: 1 - no sound output at all 2 - garbled or wrong sounding instruments (something missing drum channels too) In my experience, and maybe viletim can comment on his experiences as well, these chips are notorious for being deffective. I posted an unlisted youtube video of a few bad chips: Oddly enough we both tested with Double Dragon!

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Fri Mar 06, 2015 8:16 pm
	You should sell them at a premium price as "pre-circuit-bent" :) I thought viletim had found a lot are fake (with the quality control that implies).

db-electronics Joined: 06 Dec 2013 Posts: 335 Location: Canada	Posted: Fri Mar 06, 2015 8:28 pm
	Maxim wrote You should sell them at a premium price as "pre-circuit-bent" :) Haha! You're not the first one to tell me that! Edit: I actually shipped many of them back to the seller because they "claim" that all their stock is 100% tested and operational - bs.

fcorona76 Joined: 05 Mar 2015 Posts: 1	Posted: Sat Mar 07, 2015 2:39 pm
fcorona76 Joined: 05 Mar 2015 Posts: 1	unhuman wrote viletim wrote Crap... That's a problem... Put the capacitor that you pulled out back in between the red wire and the motherboard. I'm pretty sure that will fix it. Thanks for the suggestion viletim. Adding the cap back in has changed the sound properties, but unfortunately has not improved on the initial problems. It still sounds like there are parts missing, and still has random glitch moments like in the first video I posted. Hi...long time lurker. First time poster. I bought one of these first run new revisions too. I got to installing it the other night and had the exact same problem you did. Apparently there's a flaw in Tim's new design and it is missing the sound output cap on the board. You can make it work but you'll need the modify the install instructions a little. Remove the specified capacitor (varies by board/region revision) and solder the white wire in to the positive side of the board (my solder pad broke off so I had to solder directly to pin 10 of the VDP but it's the same thing). Next, solder the red wire to the negative leg of the capacitor (striped side) and solder the positive leg of the capacitor to the negative side of the board. Then solder your ground wire to a ground and you'll be good to go. Awesome sound and all! I'd like to thank Tim for his immediate response to my cries for help! A small design oversight that has a pretty easy fix. I don't guarantee that this will work for all revision of SMS but it worked well for my original NTSC SMS. Thanks, Frank edit: Looking at the install instructions for all the different board revisions it seems that the red and white wires change to different sides of the board (+ or - side of cap). I would guess that if you follow the instructions as normal for your particular SMS and install the capacitor with the negative leg to the red wire and the positive leg to the board (which ever position the instructions tell you) you'll be fine. yimg-1130908088-1-1638007532.jpg (3.27 MB)

zborgerd Joined: 16 Mar 2015 Posts: 1	Posted: Tue Mar 17, 2015 5:13 pm
zborgerd Joined: 16 Mar 2015 Posts: 1	I installed a v2.2 FM module, a few days ago, in my original NTSC Master System (removing C49) and had no issues. As far as I can tell, it sounds correct. I can't post links yet but you can search YouTube for video TQq6z-gAXDQ Either my board is fixed or the problem only occurs on some variations of the MS and the issue is unique to the point where the capacitor is pulled and the audio is reinserted. When did you order your board? Mine shipped out on Feb 19 2015. Edit: One more thing. Are you sure that the polarity on cap C37 isn't backwards?

Forums

View topic - FM Mod Sound Issues