Been distracted by work, but I'll desolder the op-amp when I get a chance.
- Thread starter Kujako
- Start date
Been distracted by work, but I'll desolder the op-amp when I get a chance.
Hi
This is what I hear on mine for audio probe for music
YM2151 pin 21
YM3014 pins 2, 4, 8
JRC A2004B pins 1-3 and 5-7
Volume POT pin nearest the amp
Some other things to check
The YM2151 is what creates the music, but other sounds (PCM) will be coming from the rom at IC30. You should try using a logic probe on one of the data pins and see if it pulsed when a sound would be playing. When a sound is not suppose to be playing it should be stuck low.
Logic probe pin 2 (IRQ) on the YM2151 and confirm its pulsing. It appears the sound program is setting up a timer on the YM2151, which when it expires will trigger an IRQ pulse on that pin. If this is stuck low or high maybe there is something wrong with the z80/sound rom/path from z80 to YM2151?
My sound program rom and pcm rom are physically smaller (28pins) then yours, with the left side of each socket having 4 empty pins. This maybe accounted for by @Hammy's comment regarding jumpers.
This is what I hear on mine for audio probe for music
YM2151 pin 21
YM3014 pins 2, 4, 8
JRC A2004B pins 1-3 and 5-7
Volume POT pin nearest the amp
Some other things to check
The YM2151 is what creates the music, but other sounds (PCM) will be coming from the rom at IC30. You should try using a logic probe on one of the data pins and see if it pulsed when a sound would be playing. When a sound is not suppose to be playing it should be stuck low.
Logic probe pin 2 (IRQ) on the YM2151 and confirm its pulsing. It appears the sound program is setting up a timer on the YM2151, which when it expires will trigger an IRQ pulse on that pin. If this is stuck low or high maybe there is something wrong with the z80/sound rom/path from z80 to YM2151?
My sound program rom and pcm rom are physically smaller (28pins) then yours, with the left side of each socket having 4 empty pins. This maybe accounted for by @Hammy's comment regarding jumpers.
OK... so checking pin 2 on the YM2151 I get nothing but noise
Tried it with a logic probe first, and it was constantly "high", then tried an oscilloscope and I just see noise.
Going to recheck everything and try swapping out to a different chip, but this would seem to indicate an iRQ issue from upstream of the Yamaha.
Tried it with a logic probe first, and it was constantly "high", then tried an oscilloscope and I just see noise.
Going to recheck everything and try swapping out to a different chip, but this would seem to indicate an iRQ issue from upstream of the Yamaha.
IRQ / pin 2 is an output of the YM2151. But I would agree the issue would be upstream from the YM2151 if you've confirmed its a known working chip. The YM2151 generating the interrupts is dependent on the z80/sound program setting up one of the timers on the YM2151.
Can you tell me what eprom chip you used for your sound program rom (ic33)? I will try it and see if that setup works in mine.
Can you tell me what eprom chip you used for your sound program rom (ic33)? I will try it and see if that setup works in mine.
Still working on this... code release week, so work is going to be a distraction.
Took a look at the YM2151 under a thermal camera.
Nothing too outrageous. Couldn't find any other hot spots on the board.
Took a look at the YM2151 under a thermal camera.
Nothing too outrageous. Couldn't find any other hot spots on the board.
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So it appears I have the same board and sound PAL as you. My sound rom (ic33 / 27c512) dumps to crc b8d8108c, which matches up with bbm2-sp-b.ic33 from bbmanwja mame romset. If I double up this rom and write it to a 27c1001 it works fine.
If I try to do the same with bbm2-sp.ic33 from bbmanw mame romset, it does not work. There is a specific comment in mame about them having changed the sound io ports.
https://github.com/mamedev/mame/blo...c192b817c900ad18b/src/mame/irem/m90.cpp#L1137
Perhaps you are just using the wrong sound rom?
If I try to do the same with bbm2-sp.ic33 from bbmanw mame romset, it does not work. There is a specific comment in mame about them having changed the sound io ports.
https://github.com/mamedev/mame/blo...c192b817c900ad18b/src/mame/irem/m90.cpp#L1137
Perhaps you are just using the wrong sound rom?
Yep the decrypted CPU roms are mine but the sound roms are from standard mame, so double check them!
Thanks to both you and @ack for the info, will try to recheck the audio ROMs when I can (worked some 18 hour days last week, so not doing anything this weekend).
