Master System FM Sound Mod (Etim's Board) - No Sound

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lechu
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Joined: Sat Aug 15, 2015 12:52 am

Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

I just installed Etim's FM sound exapansion into my Master System, but I'm getting zero audio. I used the instructions for the original 1986 NTSC system. I removed capacitor 49, wired the white to positive and the red to negative, the shielding to the RF modulator metal casing. I put in After Burner, and the system is showing that it recognizes the board (flashing Sega Mark III on game start-up). It just gets not audio at all. I tested my connections with a multimeter for continuity, and it seems like everything worked. The Master System had no issues before hand. I've tried on a CRT and the XRGB-Mini.

Any ideas guys? Thanks in advance.
lechu
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

Don't mean to bump, but I have an update. Still not working, but progress.

I put the capacitor back in, and kept the wires from the SMSFM board soldered in as well. I get the original sound, but still no FM sound.

I used my continuity tester again, I find continuity with the negative side of the capacitor to the audio output. I tested those points with the SMSFM board and have continuity. I can't find any continuity with the positive side of the capacitor anywhere on the board. If there's a point it's for sure connected to, I may be able to work with it. But I don't know enough about the Master System to do so. If anyone knows a point, please let me know.

Other than that, I got nothing. Any ideas?
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keropi
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by keropi »

Not really a solution but have you tried contacting Tim? He is super helpful and a great guy :mrgreen:
lechu
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

keropi wrote:Not really a solution but have you tried contacting Tim? He is super helpful and a great guy :mrgreen:
I emailed Tim a couple days ago. Waiting on a response. He's helped me in the past. Seems like a cool guy.
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RGB32E
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by RGB32E »

Can you post a picture of your installation? The installation instructions still include an outdated picture for the NTSC model, so perhaps you've got in/out swapped? Do you have one of the newer PCB revs that has a "Loud Output" connection so that you can test audio directly from the SMSFM?
lechu
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

RGB32E wrote:Can you post a picture of your installation? The installation instructions still include an outdated picture for the NTSC model, so perhaps you've got in/out swapped? Do you have one of the newer PCB revs that has a "Loud Output" connection so that you can test audio directly from the SMSFM?

I'm away from my console at the moment, but I can take pictures when I get a chance. I was not using that picture because my motherboard didn't match. It's the one labelled "Original NTSC SMS (1986)" on Tim's instructions. I can try swapping the white and red wires.

I don't know if I have the Loud Output connection or not.
lechu
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

Ok, update time. Here's some pics: http://imgur.com/a/4THNR

Sorry about the quality. Not a photographer. Also don't mind the messy soldering. I'm still learning, and I just haven't been bothered to clean it.

I've used the wires on the top and bottom of the board and nothing both times. I wired a headphone jack to the Loud Output part of the board and... nothing. Disappointed. Still have no clue why it's doing this. So frustrating.

And if it helps, my Master System is the original model, with no built in game (other than Snake)
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ApolloBoy
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by ApolloBoy »

Why is the capacitor still there? It's supposed to be completely removed.

Also the positive lead for C49 (the capacitor that you remove for the SMSFM) goes to two places. If you look closely at the board, you can see it goes off to R47 which is a pulldown resistor (meaning that the other end goes to ground) and also to Q48, which is a transistor that acts as part of an amplifier for the audio signal. The audio signal comes from pin 10 of the VDP.
Last edited by ApolloBoy on Mon Jul 04, 2016 4:18 am, edited 1 time in total.
lechu
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

ApolloBoy wrote:Why is the capacitor still there? It's supposed to be completely removed.
I did remove it. I put it back just so I could try several combinations with and without. I get absolutely no sound without it. When I put the capacitor back, I at least get the original sound. I have not had any combination of things that give me sound without the capacitor.
lechu
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Re: Master System FM Sound Mod (Etim's Board) - No Sound

Post by lechu »

My apologies for bringing up a dead thread, but I have an update. Just in case others folks have the same issue.

I emailed Tim a while back about the issue. He said it sounded like a fault with the amplifier on his board. Being the nice dude that he is, he sent me a replacement board. Swapped out the boards, removed the capacitor (for about the 30th time) and soldered the three points. Soon enough, I hear some sweet FM audio from my Master System.

So if anyone else has this issue, it may be something wrong with the board. If it happens to you, I'd email Tim, but no guarantee that he'll send a replacement board to everyone.
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