Star Wars sound board - No Speech

SaminVA

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Now that my Star Wars board is working it's time to figure out what's wrong with my sound board.
Just to recap, the sound board was completely dead as I tested it in my working game. I replaced the CPU, ROMs, SRAM ,PIA and tested the speech chip in my working sound board so with all these chips tested and replaced I now have music and sound effects but the board still has no speech. Instead of speech you get either nothing, popping or white noise. I made a video which first shows my working sound board in test mode. Then it shows my board with missing speech wile in game play and last wile in test mode. In short all it shows is what sounds should be present in test mode and which are missing on my board. I couldn't find any video of the sound test on the web so I figured it might be of some help if someone is testing their sound board and don't have a working board to compare.
Now for looking for the problem. At first I was thinking their might be a problem with the op amp buffer at 4C LF347 or TL084 because the output of the speech synthesizer pin 8 runs to pin 12 of 4C but testing pin 8 of the speech IC it has the same pops that's coming out the speakers and sense I know the speech IC is good it had to be something inputting to that IC causing the problem. Sense the PIA IC is new and tested good as well as the ROMS and SRAM and CPU and the music and sound effects are working I could rule out that and look for something in the speech section. That left the speech clock which points to 2F CD4069 or 74C04. I tested 2F with my logic probe on both the working board and the bad board and got a very different set of readings .I am putting that info and video together now so I'll post it soon. Maybe someone can tell me if I am on to something or on a wild goose chase. :)



More on the way :D
 
Hi Sam

Nice video!
Your sound, sounds kind of wobbly or is it just a problem with the video?
Have you checked the power supply to the speech chip...pin 4...should go -5v when speech is called for. Other than that you are probably in the right area..4096, 74C04 or the 161 at 3F.

I had a popping sound problem with a speech board in the past....IIRC it was the 161 at 3f....another board would constantly pop about 2 times a second...that was down to a bad 4096 at 2F.
 
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Thanks omegaman for the suggestions. I checked the -5volts on pin 4 of the speech Synthesizer chip and the -5 volts is present on both the working and nonworking boards.
I took my logic probe and checked all the pins of 2F and 3F on both boards and compared the results. I didn't find a big difference between the two 74LS161 ICs at 3F but their was a big difference with the chips at 2F. Pin 1 and 13 both connect to Q1 and I get the same readings with the logic probe on both boards which is a High Low Pulse with no beep, but on the output of pin 2 and 12 which are tied together and connect to pin 6 which is the Oscillator input of the Speech Synthesizer chip I have different readings. On the working board I get High Low Pulse with no beep just like the inputs but on the bad board I get High Low Pulse with audio beeps. Also on the working board pins 3,4,5,6,7,8,9,10 and 11 all are Low. But on the Bad board pins 3,5,7,9,and 11 are Low but pins 4,6,8 and 10 are High. Could this mean this chip is bad ? I don't think 3F could be affecting 2F even though their was a slight difference, 3F is up stream of 2F and the inputs of 2F are the same, only the outputs of 2F are different so I feel 2F might be the problem. So I think I will replace 2F but that's one of the chips I don't have but I ordered a few from Bob Roberts so I should have them in a couple days. Until then I'll pull the old chip and install a socket so I'll be ready when my package arrives . Hopefully that will fix the problem so I'll report back with the results.

 
I have a Star Wars that I collected and assembled piece by piece and it dosn't have a conventional test switch inside of the coin door. Where your test swtch is on your game? How do you put your game in swith test mode? Can you PM me
 
There is a tag labelled self test on the main board, connect it to a ground tag with a jumper cable. You can also power up the sound board on the bench without the other boards.
 
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Great video's and thread ! I didn't even know it was possible to test the sound like that.

I do think that ESB has a bit more elaborate sound tests from the test menu's than SW and since you have the Vectorlabs kit there you could have tried that as well.

Anyway, hope 2F fixes your problem.
 
I got my order from Bob Roberts today so I could hardly wait to put a new 4069 in the sound board and try it out. I had already pulled the old chip and installed a new socket so I popped in a new chip and put the sound board back on the board set and fired it up. Put it in test mode and I have speech. The Force is back. :D
So now the only thing I need to make it 100% again is another VGA replacement chip and both boards will be done. Now I need to rebuild my control yoke which has some slop because half of the screws are missing and the rest are loose and I have one split gear and the rubber bumpers have melted. That might be another thread.
I would like to thank everyone for the help, especially omegaman, I appreciate all the advice.

 
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