Joust that is a mute

trissa

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Hoping someone can help me with a no sound joust.

Have no sound at all. does not play any sound when the diagnostic sound board button is push.

went thru diagnostic checklist.

getting 10v at TP1 and pin 5 IC1

Getting 5 v where I should be

power supply is giving 11.7 v @ power supply and 11.4 at header pin on sound card

did the test for volume pot and speaker and test ok
did test for analog section and test results as should be.
Check data lines from rom to sound board both at rom board and sound board and data is behaving as should.

Is 10v to low to fire sound board?
Cap problem?
is it a rom (ic12), PIA, or some other IC problem.

Any help is appreciated.

Trissa
 
You need to get a logic probe and check:
1) the invertors that are between the cable and the PIA (IC5 & IC7).
2) If those check good, you need to try the pins 2-9 of the PIA to see if it is pumping data to the DAC.
3) If it is, then you need to test the output of the DAC. This is on pin 4. Use a multimeter.
4) If you are getting voltages that vary on the output of the DAC, try Q2. You should see higher voltages at the collector (measure at the + side of C29).
5) Measure at the - side of C29. If not seeing voltage fluctuations, replace C29.
6) Test that you are seeing data on the data lines. THis might indicate a dead CPU or bad ROM.

Or you could just shotgun it and start replacing the caps, the voltage regulators, the CPU, the PIA and the ROM.

10V is sufficient to run the amp.

If you are not getting any sound at all when you press the diagnostic button, it is likely either the amp or one of the sata related chips, CPU, PIA, ROM or DAC. The reset button bypasses the invertor chips and locks the CPU into a loop playing sound 1.

ken
 
You need to get a logic probe and check:
1) the invertors that are between the cable and the PIA (IC5 & IC7).
2) If those check good, you need to try the pins 2-9 of the PIA to see if it is pumping data to the DAC.
3) If it is, then you need to test the output of the DAC. This is on pin 4. Use a multimeter.
4) If you are getting voltages that vary on the output of the DAC, try Q2. You should see higher voltages at the collector (measure at the + side of C29).
5) Measure at the - side of C29. If not seeing voltage fluctuations, replace C29.
6) Test that you are seeing data on the data lines. THis might indicate a dead CPU or bad ROM.

Or you could just shotgun it and start replacing the caps, the voltage regulators, the CPU, the PIA and the ROM.

10V is sufficient to run the amp.

If you are not getting any sound at all when you press the diagnostic button, it is likely either the amp or one of the sata related chips, CPU, PIA, ROM or DAC. The reset button bypasses the invertor chips and locks the CPU into a loop playing sound 1.

ken

Sorry for my lack of knowledge but what should the logic probing of inverters values be?

All of the 2-9 pins on the PIA probe high

Pin 4 DAC -.628

How do I check for data on data lines?

Sorry Ken for the dumb questions
 
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