(Topic ID: 293920)

System 11 Music but no speech ( Jokerz and Cyclone)

By R67en

1 year ago

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  • 9 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by R67en
  • Topic is favorited by 1 Pinsider


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#1 1 year ago

My Jokerz has music, but no speech. (Fortunately, I have a functioning Cyclone with the same CPU board)

On boot up - I get one beep indicating everything's working.

In diagnostics, it advances through music, all music tracks play. Sounds advance through from 1 to 7 with no errors, but no speech/sfx sounds play.

I hit the button on the left side of the CPU board. It's supposed to play two test sounds, one for CVSD, one for DAC. Neither play.

I swapped U15 and U24, after reading that if one was bad, it wouldn't boot. It booted and played just fine tho.

I swapped sound Roms into my Cyclone, and all the speech/sfx worked, so U21 and U22 are good.

I swapped the whole CPU board from my Cyclone into the Jokerz (Jokerz Roms swapped in), and everything works there, so I know it's a CPU board issue.

I'm looking at the manual, and it's vague enough that I can't follow. (I'm also a noob trying to learn)

1. It says to test pins 2-9 on U9 to see if they pulse on sound test. Noob question, how do i know which ones are pins 2-9? Do I test this with an electrical tester? How? connect to pins 2 and ground and see if it lights up?

2. It says to check -12 voltage. I put my meter on the -12 test spot and the ground on the board. A buzz came from the speakers, but it showed 0v. I'm sure I'm doing something wrong there. I tested the working board and it did the same thing. How, specifically, do I check for 12v?

3. It says to check if AC ripple is too high? How do I test this, and what exactly is "too high"?

4. The gray and Gray Green wires are supposed to be tested for 19.4 VAC. I don't think that's an issue since the board swap works, right?

5. It says to check the C26 capacitor for -12VDC. How exactly do you do this? Where do leads go on multimeter?

I've read up a bit on here, and I'm about ready to just shotgun approach it and replace the PIA at U9, the CVSD at U3, the amps at U4 and U5, resistor at SR1? Any idea how I can test and narrow down the issue?

Thanks for all your help!

#2 1 year ago

The CVSD is a possibility if you are just guessing. The mixer section has a lot of discrete components and is best traced with an oscilloscope following the audio path. I found a shorted capacitor in the mixer section on my F-14 that was causing no voices.

A lot of your questions are basic electronics questions. ICs have a mark such as dot indicating pin 1, or a half circle cutout indicating one side of the IC. Pin 1 starts on the left and counts up in a counter-clockwise direction. You can use an oscilloscope or logic probe to determine highs and lows of digital signals, an oscilloscope to analyze audio waveforms, or frequency counter for timing analysis.

Make sure your meter is set to DC volts for checking that -12vdc. To measure AC ripple take the same measurement with the meter set to AC Volts. Typically you want ripple less than 1volt AC and the lower the better. 2 VAC or more is a big failure, usually filtering capacitors.

I've run out of time for more at the moment. But will check on this thread another time.

Screenshot_20210523-081436 (resized).png
#3 1 year ago

Thanks! I am admittedly a noob trying to learn.

Looking at the schematics, there's a lot of parts that the entire circuit passes through that could be the issue. Any advice on isolating it I'd appreciate!

Someone has socketed the cvsd and the soldering doesn't look great. I'm going to dig into that, and maybe just replace the chip since it's obviously gone bad before.

#4 1 year ago

One thing I'm noticing is that my 10k resistors vary wildly. Some show 6K, others 10.5K. How concerning should that be? When a resistor 'fails', what tends to happen to it's resistance?

#5 1 year ago
Quoted from R67en:

One thing I'm noticing is that my 10k resistors vary wildly. Some show 6K, others 10.5K. How concerning should that be? When a resistor 'fails', what tends to happen to it's resistance?

My first question is, are you disconnecting one end of the resistor to measure it? That is the most reliable way to get a valid measurement. When a resistor is measured in circuit, other components connected affect the measurement...not always, but it depends on the circuit. Resistors have a tolerance around the rated value. A common tolerance is 20% (tolerance values are often indicated by the resistor color code banding) A resistor that is marked as 1000 ohms can measure between 800 and 1200 ohms and still be in its rating. A hard "open" resistor that measures near infinite restance or a "shorted" resistor measuring very low ohms can be a problem. The effects of a failed resistor vary widely with its use in a circuit. One suggestion is take some good clear photos of both sides of the board around the CVSD - perhaps we can identify something visually.

#6 1 year ago

Ive had the cvsd fail in a pinbot and taxi.

#7 1 year ago

Fixed this issue dozens of times

IF it's no speech AND no sound effects then it's the Op Amp at U5 it's a 1458 chip. 100% will be this if you have good Roms, good Ram at U23, good PIA at U9 and good CPU at U24. Next possible culprit would be a bad Ram at U23. seen that quite a few times.

If it was just NO speech but the CPU based sound effects worked then you would do these

Change these parts in this order.
Op amp at U4 a 1458 chip
Cap at U15 10 uf
CVSD at U3 55536 chip or equivalent

Find it's the Op amps 45% of the time, CVSD 45% of the time and the Cap 10% of the time. I've never had it be anything other than these parts.

If it was just no sound effects but the speech worked then you would do the 10 Uf cap at C8 or the 1408 DAC at U2

2 weeks later
#8 1 year ago

Update! Finally got some new parts. I first replaced the cvsd, since it was socketed.

Game ran and more sounds are playing. Plays a sound on every sound test.
What's interesting is that I've swapped boards in cyclone and Jokerz. Now the cyclone is playing new sound I've never heard before. Some speech is incorrect tho. Starts at the wrong spot and ends early.

Fixed a couple other minor playful issues and started it up. Now it says u10 pia failure on the display and won't start a game.
The CPU board diagnostic led flashes 8 times. Then there blinking led flashes 10 times.
The sound board test at left now beeps 2 sounds like it should.

Should I go ahead and replace u10?

#9 1 year ago

Once in a while the game boots and starts a game. When that happens, there are no flippers.
I've got 4.82 volts at test port and pin 20 of u10. Did a diode test on u10 pins 2-17 and the tested fine with the chip still on the board.
Should I replace c8? It just go for u10?

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