Cinematronic Armor Attack Sound Problems

divingbuddy

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http://forums.arcade-museum.com/showthread.php?t=265168

I have a working Armor Attack, but the sounds for the tanks and the jeep fire is not working. I have started to replace some of the ic chips but before I get to far into the IC replacement, I would like to know if anyone can help me pinpoint the IC chips that I need to replace?

I bought several IC chips and sockets. I am using the manual trouble shooting guide to help me start the process in replaceing the ic chips.

If anyone has a working AA sound board, I am interested in purchasing it.
 

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I don't have an AA, but looking at the schematics, do all the other sounds work? Before I replaced IC's, I'd check the transistors. Q2, Q3, Q8, Q9. Those would tend to fail first... you can check them with a multimeter. Also C22, C23, C24 and C31, C32, C33 are in those circuits. If those don't do it, try IC19 and IC22.

There's really no chips that just share those two sounds, so nothing obvious. You probably have two seperate problems making the two sounds dissapear.
 
I will check the board again and try one thing at a time......thanks for your help.

Yes the other sounds are working great.
 
O.K., I was just checking because there's a chip that 4 of the sounds run through, and another that 8 run through... they could have dead lines on just those two sounds though... but it's more likely something specific to each of those signals.
 
I found this information on the Vector List. I will be doing more parts replacements.

A post from Bill Boucher:

Re: Armor Attack sounds and rom versions
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From: William Boucher <boucher_at_mnsi.net>
Date: Thu Jun 04 2009 - 17:49:38 EDT

>what do the opamps do? What actually amplifies the audio to send to
>speakers?

The opamps IC19,20,21,22 are voltage-controlled current amplifiers
(transconductance amps). They output a current signal proportional to the
sum of the noise generator and the voltage envelope signals that are
generated by 5 groups of R, C, and Q components. Each of the current
signals represents a shaped-noise sound effect. These current signals
comprise group one of sounds (Tank fire, Lo explosion, chopper, jeep fire, &
hi explosion). These current signals then all pass through a resistor R90
(100k) where the sum of the currents is converted into a voltage signal.

The voltage signal representing the group one sounds then goes through opamp
IC25 which is nothing but a buffer (unity gain amp) and then is coupled by
cap C43 into another opamp IC26. The resistors R91 and R92 set the gain of
the opamp IC26 to about 2.4.

Resistors R7 and R14 bring the Tank engine & squeak sounds into IC 26 also.
Resistor R7 sets the gain for the tank engine to about 0.8. If the value of
R7 is too low, the engine sound will be too loud. R83 brings into IC26 the
beep signal from the 555 oscillator IC23. The tank engine, squeak, and beep
sounds comprise group two of the sounds. IC26 has summed together both
groups.

The output of opamp IC26 represents the sum of all sounds but it is a
relatively weak signal. It goes out through the volume pot and returns to
the input of opamp IC24 (at pin 3). Resistors R25 and R84 basically set the
DC gain to about 26. C39 limits AC gain to reduce noise and to keep the
amplifier from oscillating. The output of IC24 through R85 and R87 drive
the bases of the final power amp stage transistors Q12 & Q13 which then
drive the speaker through R88 & R89. The two diodes D6 & D7 protect the Q12
& Q13 base-emitter junctions from damage from reverse-bias voltage that
would otherwise occur during the half-cycle at which the transistor is off.

William Boucher

Thanks Bill
 
Bump.......still working on the board....WTBorrow a working sound board to help trouble shoot my sound issue.

Or, WTBuy a working sound pcb. Send me an asking price..I will consider all offers..
 
I got the CPU pcb and sound pcb board today from Quarter Arcade. Both boards were untested. I installed the boards, powered them up and I got no chatter and both power reset switches popped. Shut down and pulled the CPU pcb board and installed the original CPU pcb. Powered up the game and heard chatter, the game came up on the display, coined up and started a 1 player game. The sound was still the same with the new sound pcb.

I now know the problem is on the CPU pcb because both sound pcb's are missing the tank squeak, jeep engine, gun fire, and explosion of the tanks when hit.

Reseated the all the socketed chips, no luck.

Changed ribbon cable coming from the sound pcb, no luck.

Pulled the CPU pcb and checked the underside of the board, clean and no burn marks. So I started to follow the trace lines from the ribbon cable connection on the CPU board to the IC chip located at F2. This chip was socketed, checked the chip numbers and they were different #'s.

So now it was time start chip swapping. So I decided to start with IC F2 on the CPU pcb because it was the first IC connected to the sound ribbon cable.

I swapped the chips, crossed my fingers and powered up the game. I got the explosion sound on startup as normal, waited for the monitor to power up and the game started in attract mode as usual. Coined up the game, pushed the start player one button, the Morse code sound played, so far so good. The tanks appeared and started to roll.......and I now have all the sounds working, Oh YEA!!!!!! I played a couple games with all the sounds working.

The working IC chip is SN74LS259N and the bad IC chip is 74LS59PC.

I read and reread the manual. I could not find any reference to the IC chip in the trouble shooting section in the manual referring to the CPU pcb @ F2, which is described as an IC 8 bit latch chip. I hope this thread helps someone else out fixing their sound problems.

My work is done.....time to go play some Armor Attack!!!!!!
 
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