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Jaguar sound static issue


Dr.Buddha

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I picked up a Jaguar that has the R/P board. Everything seems to work but theres terrible static over the top of any sound thats played. Its not static all the time, just when a sound is played. It does it both on RF and with one of those composite adapters. Reg1 is outputting 5v as normal and the whole board is recapped. I thought it might have been an issue with the cap job but that turned out not to be the case after further investigation. All the caps are the correct rating and seem to have intact traces. I posted a video to the consolerepair subreddit if that helps.

 

 

Thoughts?

Edited by Dr.Buddha
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7 hours ago, eightbit said:

Did you try to connect this to another audio source with the same result? A set of amplified speakers or a stereo receiver?

2 different tvs and the guy I got it from said it did the same so thats at least 3 different devices

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17 hours ago, oakcitycomics said:

Are you using the Atari power supply? I know some of these cheap ones everyone is hocking off on amazon and ebay cause static with a lot of the retro consoles. Very common issue on Genesis and SNES. Just a thought 

using a genuine power supply that works fine with other systems

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17 hours ago, Zerosquare said:

Check the audio signal on pin 6 (left channel) and pin 8 (right channel) of U5 (located on the bottom left of the PCB). Is it distorted as well?

is it a line level audio signal coming out of those pins? trying to figure out a way to check them without a scope.

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20 hours ago, Zerosquare said:

Check the audio signal on pin 6 (left channel) and pin 8 (right channel) of U5 (located on the bottom left of the PCB). Is it distorted as well?

Well I  soldered on some wires to pins 6 and 8 and connected them to some powered speakers. Yes, pins 6 and 8 are producing static hiss with game sounds barely audible underneath

 

Would that mean U5 is most likely needing to be replaced or something further back in the line?

Edited by Dr.Buddha
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- Check if the supply voltage on U5 is correct (pin 5 is +5V, pin 4 is ground).

- Check the voltage between the common point of R64 and R65 (AVREF) and ground. It should be about 3.3 V.

- If you have an oscilloscope : check that the waveforms on pins 1, 2 and 3 are clean. Pins 1 and 2 are square wave clocks, pin 3 is a digital bitstream.

 

If all those checks don't show anything wrong, U5 is likely defective.

Edited by Zerosquare
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4 hours ago, Zerosquare said:

- Check if the supply voltage on U5 is correct (pin 5 is +5V, pin 4 is ground).

- Check the voltage between the common point of R64 and R65 (AVREF) and ground. It should be about 3.3 V.

- If you have an oscilloscope : check that the waveforms on pins 1, 2 and 3 are clean. Pins 1 and 2 are square wave clocks, pin 3 is a digital bitstream.

 

If all those checks don't show anything wrong, U5 is likely defective.

5v supplied to U5 and 3.3v on R64 and 65. sadly I dont have a scope yet so I guess I'll just go ahead and try to replace U5. They seem to be around $5 on ebay so no big loss if it doesnt help. Thanks for your help. I really appreciate it.

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  • 3 weeks later...
On 6/9/2020 at 5:19 AM, Zerosquare said:

Try desoldering U10, and connecting pin 12 to pin 9.

went to desolder U10

wasnt paying attention and desoldered U9 instead

cursed a lot

went to resolder U9

dropped it off the table into carpet

cursed a lot

found and resoldered U9

desoldered U10

soldered a jumper from pin 9 to pin 12 where U10 used to be

same static audio issue

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43 minutes ago, Zerosquare said:

Last try: check continuity:

- Pin 58 on U15 ↔ pin 1 on U5

- Pin 59 on U15 ↔ pin 12 on U10

- Pin 60 on U15 ↔ pin 3 on U5

all have continuity... Itll be heart breaking to junk this system when its so close to working, but unplayable is unplayable.

 

Thanks for your help

Edited by Dr.Buddha
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