Phoenix
Williams, 1978You're currently viewing posts by Pinsider barakandl.
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if you have the sound board with one fuse it needs modified to work with a 6821. I think they forgot a pulldown resistors on CB2 or something and it causes only the 6821 to act up. The diag button makes noise, but it does not respond to inputs from the main cpu/driver. The flash manual has information on modding the one fuse sound board to work with a 6821. Page 21
you have the first generation sound board with one fuse and a few design mistakes that got fixed with the red wires. Please download and review the flash manual if you dont have one. Check around page 21. Otherwise you may be spinning your wheels just doing stuff. It looks like you need to solder together p39 and p40 of the pia at the least.... can't say thats the only issue tho as that usually only makes the sound board not respond to the cpu/drive stimulation but the NMI button produces sound.
The ceramic package CPUs have better temperature ranges... I think that is it. They are long obsolete still can and do fail. Specially if zapped by over 5v or negative voltage. I was told by someone at Rochester Electronics they where going to spin up more 6800 series stuff (be they would be crazy expensive). Not sure if that is true...
The red wires on the back of the board.... looks like it could be impaled by a lead and shorted out. Seen that happen.
Break the sound board into three sections.
The power supply. +12v, -12v, +5v all must be good.
The computer. Is the CPU running? Check the E pin for 0.85mhz clock. Put a logic probe on the PIA ports that service the digital to analogue converter. Push the diag button and monitor. Does the PIA start doing work when sound plays??? If so the computer is problem running.
The sound amplifier. If the computer is running but no sound you probably have an analogue failure. You can send some noise through the amps to see if they are working.
If you wan to just take the easy way out. You can buy an entire new replacement from http://nvram.weebly.com. The trace routing errors are all fixed and they generally produce cleaner / better sound than the worn out originals do.
Quoted from MaxAsh:zacaj barakandl Cap kit done, not a big surprise it didn't fix the issues. Tomorrow I guess I will tackle replacing the two 40-pin SCANBE sockets to see if that does anything. I may stare at the 80 solder points for a bit and just order a board instead, but we'll see. I do like a challenge, and I've done plenty of these now. That doesn't mean they're fun though!
I'll probably try to figure out some of barakandl's suggested tests first though, since I have it hooked back up at the moment.
The digital to analogue converter chip, MC1408L i believe, is connected to the 6820 PIA. When you push the diag button on the sound board some/all of these pins should become active or pulsing with a logic probe. If that happens the computer is at least mostly running.
When you replace the IC sockets it will give you a chance to do / check the mods in the flash manual. You don't have to change the jumpers. It appears you are using a masked PROM and the flash manual is talking about a ROM or something with a 2716 pinout / operation.
Pages from Williams_1979_Flash_Manual-2 (resized).png
Pages from Williams_1979_Flash_Manual (resized).png
Quoted from MaxAsh:barakandl - just wanted to say thank you, the new board works great! Simple plug and play, hooked it up and it worked immediately. Only comment I'd have on it is that the sound was defaulted to "chime" and not the more modern sounds. SW2 had no jumper connector on it. I had plenty of PCB jumpers from various computer motherboards, so I threw it on there and it worked great!
zacaj - thank you as usual for all your help as well. I'm going to keep working on the old sound board since I have this machine to test it in for now. Hopefully I can fix it and have it as a future part, or sell it if need be. For now, I'm just happy to have a working sound board in this nice Phoenix!
Time to move on to the other stuff... new rubber rings, leveling some cupped inserts, cleaning and adjusting more switches, rebuilding some flippers. Fun stuff!
OK great to hear. I normally send the board out with the jumper shunt in for the advanced sound mode. I must have forgotten to do so on that PCB. Interesting to me is the Lazerball I use to test the sound boards must not have a chime mode with the sound 2 ROM as it was playing the same advanced sound effects when I tested it. I will have to check out to see what games / ROMs have a chime mode.
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