Berzerk question-Popping sound before/after speech

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This was just one I figured I would throw out there because I have searched and can't find any info out there on it. My Berzerk makes a popping sound before and after every speech sound. All the sounds of the robots firing are fine. A friend of mine suggested replacing the TDA 2002 IC on the SB-1000 board which I did (twice) to no change. It's not something that affects gameplay, but I just would like to get rid of that popping sound if it's possible. Any ideas?
 
i would start by replacing any electrolytic capacitors that are in that circuit

without looking at a schematic, i dont know what value it might be

those things dry out and all kinds of screwy things can happen when they go bad

an ESR meter can test them so you can verify if it indeed is bad
 
You've got me trying to remember if mine does that or not as well. I think it does after some of the comments, but not all of the time.
 
Not sure if Berzerk mutes all the other sounds with the speech is playing. If so, you might consider the 4053 @ C2. It appears to alternatively select/ground some portions of the (regular) audio.

Also may look at the VSU board, which actually generates the speech. C5, C6, and of course the synthisis IC @ C3 (those are IC locations, not cap numbers). Any as mentioned any electrolytics on the board.
 
This is where an oscilloscope or audio probe would come in handy.

You use them to backtrack through the audio circuit to find the source of the problem. It sounds like a voltage spike is coming in somewhere in the circuit. Electrolytic caps are often used in audio circuits to block the DC component and allow the AC signal riding on top of it through. That's why they are common sources for this type of issue.

Bad op-amps can cause this as well. A scope or an audio probe should help you find that pretty quick.
 
This happens on my Berzerk as well.. just fired it up today. It was
pretty obvious.

Any ideas? I'm guessing the sound board but who knows. I am going to
swap the ZPU out and pop in a berzerk/frenzy zzpu to see if that helps.

Any ideas beside an oscilloscope? (which I havent boiught yet).
 
I always thought it was normal. I actually bought a filter for mine once (similar to the scratch filter on a record player) but never installed it. I was gonna use it to filter the sound before having the audio run to a stereo receiver. I never got around to it. The pops don't really bother me anymore.
 
My Berzerk has the popping too, and I made 2 other working board-sets for friend's Berzerk machines and they all showed the same pop sound. I've been switching voice and sound boards around, nothing made any difference.

I checked all the electrolytic caps with my ESR meter and they're all fine, I don't believe it is a cap issue (see others who have replaced them but still have it happening).

It probably is a "feature not a bug"....maybe it just happens when this speech chip gets turned on and off and they should have provided a means to mute the output while turning it on/off ?

Some Stern pinball machines used the VSU-100 board too so maybe these show the same popping ? Guess it's not as noticeable with a pinball machine though...
 
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Seems it's not the voice chip itself to blame.

I googled this document about the TSI S14001A speech synth:

http://www.docstoc.com/docs/42278782/TSI-S14001A-Speech-Synthesizer-LSI-Integrated-Circuit-Guide

It mentions some other devices using the same voice synth and I searched youtube for those devices to see, no hear what they sound like.

Here are two videos of the Talking Chess Challenger by Fidility Electronics. Both videos have rather poor sound quality and a lot of surrounding noise, but it's clear enough there are no pops before or after words being spoken:



 
Mmmm, this one has a bit better sound and I do seem to hear at least the pop at the end of each speech sample being played:



Of course this application uses a much smaller speaker compared to Berzerk so it may be a bit less noticeable.

(It's talking German by the way)

Seems like it maybe the speech chip itself after all.....in that case....JROK has some work to do ;)
 
Looking at the schematics for the voice stuff, it shows that everything is capacitively coupled. Speech Synth--> Low-Pass filter --> Volume control (IC C6 with ladder network)-->Buffer Amp.

Altho it could be anywhere, I would suspect it woudl be post-volume control - make sure the ladder network of resistors are all OK, and even the small-value caps (0.1uf) are not shorted.

As stated here by several, the best way to track where this starts is with a scope.
 
We need to remember the mfgr's were not shootin' for perfection when these games were released. I'm sure they could have resolved the pop issue (as could a clever tech on this forum), but I'd assume they thought it would not be noticed in the din of a noisy arcade. Good enough....send 'em out the door.

The conversion of the hardware from monochrome to color ("bullshit color") was another example of the good enough philosophy.
 
Hah, that was clever to use that song as a source from the past ! :) Stupid music editors too to not cut it out ;)

Anyway....if we all agree the pops belong in there, a "perfect" emulation would pop too :p
 
I seem to remember it both ways - there were some cabs out there that did pop (which worked every one of my anal-retentive nerves) and ones that didnt.

Maybe an undocumented manufacturing rework fix was put in place?
 
that could be. man, i don't know if I could handle a speech pop sound all the time myself. didn't the intercom in gradeschool do that during daily announcements in the morning? ;)
 
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