need a guru to look at a sound card drawing

pinnut

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i uploaded the schematic for my coney island gun game. its supposed to generate a gunshot sound, with a ricochet sound. the ricochet is fine, the gunshot non existant. both pots test good. originally, i thought one pot for each sound, but it looks like otherwise. i replaced some caps with what i had in stock, am waiting for a few more. can anyone interpet the drawing and let me now what might be suspect as to no gunshot. i tried a diff speaker. pots are cleaned, and check good on an analog meter. the image is also here:

http://s408.photobucket.com/albums/pp163/mhooker32/coney island sound card/

i can email a copy if needed. i'm stuck as to what could be causing that sound to go missing.

thanks
mike
 

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If I were you, I'd just give that sound card to me - I've got a "Shoot Out" that's missing that sound card (it uses the exact same board), and I'll take one sound over none :)

My understanding is that this board is only for creating the gunshot sound. One pot is for adjusting the "tone" of the gunshot, and the other is the master volume control. Looking over my Shoot Out schematic shows a single input going into that "tone" pot, which in turn feeds into the volume pot, which goes through the amp. and out to the speakers.

In short - I think your sound board is working as intended.

See: http://www.youtube.com/watch?v=RIA4Il9DcSQ

Hard to tell whether the gunshot sound is even active in that video though.

Now, if you're getting a sound, but it's just not quite right, you're probably going to just have to go through the whole circuit. Replace the electrolytic cap's (I'd just do them all - big ones for filtering the AC, as well as the smaller ones in the actual sound generation circuit given their age, it's a good idea to replace them anyway). Use a meter to verify that the various resistor values match up with the schematic, that the diodes are all good, and checking out the 7 transistors should be quick/easy as well.

If you happen to have an extra one of these, or know somebody that does, I've been hunting for one for a while. I found one guy selling one, but he was asking $86 + shipping - a bit steep for my tastes, and I'm about 25% through building one from scratch anyway - there's really not that much to it.

Good luck!
 
If you could email me a better version of the schematic I might be able to read it better. The one posted is too hard to decipher when enlarged. No promises, but I wouldn't mind taking a stab at it.
 
i'll try to make a better scan, in a few days

thanks
 
Check each of the transistors. I believe the gunshot is noise generated by Q6 or Q7, but all of the other transistors are related to the amplification and delivery of both sounds. Testing these components should be fairly easy since there are only two types, and the schematics for each are on that drawing.
 
sorry, i hit send too soon. sprout, does your game have the gunshot shot sound, the ricochet sound, or both sounds?

thanks
mike
 
Mike,

In my case, neither :) I'm missing the board altogether as noted in my earlier response - I just have the 8-track tape with the background music.

I started building one from scratch since it's a very simple board, but now that the game is over at my brother's, I've not really been motivated to finish up the board since I don't have easy access to the game for testing it.
 
if you get an urge to finish the board, you could mail it to me and i could try it in my game. how did you plan for connecting it? are you going to use an edge connector like originl/
 
Without looking too deeply at it, the control line is fed to Q1 thru C1, shaping the pulse to a set time which drives the base of Q2.

This is where things might get useful: the pulse from the control then feeds D1 & D2 - this looks like 2 different oscillators. And thats about where I stop. If I had to guess, I'd say the osc that is fed by D2 is the gunshot, and D1 the ricochet, just based off of complexity.

Try jumpering from the emitter of Q2 to the cathode of each diode and see what you hear. You might be able to narrow down which part of the circuit is not functioning.

Good luck.
 
Oh, one last thing; from C6 to the right appears to be nothign more than sound filter/summing amp.

There are an awful lot of electrolytics on that old board - start with replacing them all.
 
if you get an urge to finish the board, you could mail it to me and i could try it in my game. how did you plan for connecting it? are you going to use an edge connector like originl/

Yep - just going to make my own edge connector - small number of pins, and shouldn't be much of a hassle. My brother's about 20 min's away, so not a huge hassle to test it once it's finished, but since I'm not staring at the game in my garage, I've just not had the incentive to work on it lately - especially since I've had pinball after pinball to repair and shop out..
 
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