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IREM BomberMan World no audio diagnostics help request. YM2151?

Socketing in the new YM2151, the board wont even boot. If I put the old one back in, it boots but still no sound. Thinking the new one is fake... it doesn't look authentic.

Original on top in the socket, "new" one on the bottom looking suspect.
1652384480206.jpeg
 
Oh yeah, you gotta be careful with those, there are a bunch of fakes being sold.
 
The YM3014, is also fake (Y3014?, there's an M missing LOL)

I'll put you an original one of each with this namco motherboard.. I prob. have some of those LM's too.
 
Hammy said:
The YM3014, is also fake (Y3014?, there's an M missing LOL)

I'll put you an original one of each with this namco motherboard.. I prob. have some of those LM's too.
Click to expand...
Fairly sure the 3014 is legit, later runs dropped the 'M' it looks like. Hard to find one with the 'M' in new condition. But I could be wrong, not done any controlled tests... so I appreciate the offer.
 
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do you have a working game you can test them in?

btw, the 2151 is obviously fake, they milled the top down and added the print.
try wiping it with acetone :D
 
stj said:
do you have a working game you can test them in?

btw, the 2151 is obviously fake, they milled the top down and added the print.
try wiping it with acetone :D
Click to expand...
Agree re: the 2151. But it's sat around too long for me to complain to anyone about it. I may have another board that uses the 3014, but I would have to desolder a working chip to test this one out. Not really worth it...

As a sanity check, I went back and looked at the photos of the original IC.
1652447711930.png

It too lacks the aforementioned "M". That's just how a lot of these are labeled it looks like. Now the old one is marked YM3014B and the new is YM3014... I don't know that makes any difference. Not finding a spec sheet that lists differences in the A vs B models.
 
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stj said:
you could scope your working board - to learn what a good chip has on it's pins :)
Click to expand...

Far as I can tell with my scope, the new one is the same as the old. The problem is that I can't really interpret the digital signal coming in. So it may be digital static in, analogue static out. But I'll check what I have this weekend and see if there's anything I can use as a sanity check. Also may hunt around in the parts pile for a Y3014B just in case that 'B' is important...
 
Resurrecting this project having gotten some more YM2151 and YM3014 chips to try out from @Hammy, unfortunately they exhibit the same behavior. Based on my lil audio probe I'm fairly sure the issue is before the amplifier. Will see if I can find a working board with a similar chip setup in the vault (well the pile) to test as @stj suggested, and will also see if I can trace back from the input pins looking for breaks in the traces. Can't think of much else I can try...
 
Ah, that sucks...
On a good note it's at least narrowed down :)
 
Most of the results I can find re: testing a YM2161 with an oscilloscope seem to be my one failed attempts... however I did find a repair log for a Sega 16b that includes testing the input channels, saving me the trouble of doing that myself (the 16b being one of the systems I have around that I was going to utilize).
https://www.jammarcade.net/category/repair/page/2/

Probing with the oscilloscope revealed the YM2151 serial data were present on the input of the YM3012 (pin 4) but the output (pin 11) tied to the OP-AMP was silent :
YM312_scope_analyzing.jpg


I do get an output signal to the YM3014 (16b uses a 3012). But this at least confirms I'm checking the right places and my tests look correct.
 
well now i will tell you - change the op-amp.
incase it has a shorted input - opamps are cheaper than dacs
but first - does it have anything else on that line - like ceramic capacitors?
 
stj said:
well now i will tell you - change the op-amp.
incase it has a shorted input - opamps are cheaper than dacs
but first - does it have anything else on that line - like ceramic capacitors?
Click to expand...
To be clear, the picture in my last post was from an unrelated repair log. I only brought it up as it shows the input serial data I'm trying to compare against. In my case, I seem to have input to the YM3014 as well as output. But it's not "sound" in that through the built in amp or an audio probe it seems like a constant static background noise.
 
I had to do something similar to fix the audio on a Sega System 24 board: Broken audio on System 24

This also has a YM2151 but it's paired with a YM3012 (similar to the System 16b you mentioned). I used an audio probe on various parts of the circuit and I found I was getting something recognisable as the music on the SO pin (21) of the YM2151, which is likely wired to the SD pin (4) of the YM3014. Even though it's serial data, you could still hear the music with the probe (compared to say, what MAME sounds like) so I knew the YM2151 was good.

Turned out it was the YM3012 that had gone bad, but at the time I ordered both a new one of those and a new TL084 Op-Amp which was the next chip along in the circuit.
 
bodgit said:
I had to do something similar to fix the audio on a Sega System 24 board: Broken audio on System 24

This also has a YM2151 but it's paired with a YM3012 (similar to the System 16b you mentioned). I used an audio probe on various parts of the circuit and I found I was getting something recognisable as the music on the SO pin (21) of the YM2151, which is likely wired to the SD pin (4) of the YM3014. Even though it's serial data, you could still hear the music with the probe (compared to say, what MAME sounds like) so I knew the YM2151 was good.

Turned out it was the YM3012 that had gone bad, but at the time I ordered both a new one of those and a new TL084 Op-Amp which was the next chip along in the circuit.
Click to expand...
At this point I've swapped out both the YM2151 and YM3014 for known good chips with no effect. And while I do detect a signal in and out of the YM3014, it is not recognizable as "sound" but is more just background noise. So either there is an issue between the two, or an issue with the data coming in. Going to have to delve into testing the traces etc I think... but will also try re-probing with the new chips to triple check things.
 
Kujako said:
At this point I've swapped out both the YM2151 and YM3014 for known good chips with no effect. And while I do detect a signal in and out of the YM3014, it is not recognizable as "sound" but is more just background noise. So either there is an issue between the two, or an issue with the data coming in. Going to have to delve into testing the traces etc I think... but will also try re-probing with the new chips to triple check things.
Click to expand...
So I definitely could hear the tune being played, not perfect as it’s not analogue audio but enough to give me the hint the YM2151 was good and getting fed data.

If you have any other working board with a YM2151 on it, you could just try probing SO on that to make sure I’ve not been on the crackpipe :)

The only other thing I did before I got the audio probe was to pull every ROM and dump them and compare them to MAME just to make sure one hadn’t gone bad. Of course, they all verified 100% as that wasn’t the fault
 
bodgit said:
If you have any other working board with a YM2151 on it, you could just try probing SO on that to make sure I’ve not been on the crackpipe :)
Click to expand...
I do this same thing on ddragon boards when testing. You can hear the music on pin 21 with an audio probe if the ym2151 is working.

I'm just seeing this thread. I have a bomberman world I can probe around on to verify what chips/pins you should be able to hear sound on the audio probe.
 
Another possibility is the op amp is pulling 3014's the signal down.

RE: this ... maybe a bit late and you pulled it anyway...
You could bend the ym3014's OUT leg so it's not contacting the board and test it there rather than pulling the op amp. or testing in circuit...
 
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