Falcon sound problems (DSP)

[kohli79]

That is strange, if anything it should be more stable with delay on. I wonder if your falcon master clock is to low voltage on the input of the clock patch or more noise than normally there, can you scope all the clocks in and out of the patch ?

But please try disconnect everything plugged in, also have you tried s different PSU ?

The power supply is recapted with your capacitor kit! But I can also try another one again.
Unfortunately, I can't test it, I would have to send it back to my computer specialist. He's got an oscilloscope.

First I test with a different PSU and without connections.
Can I also use a multimeter to test which voltages are present on the clock patch? I would have that there. Sorry I don't have the experience!

[exxos]

The power supply is recapted with your capacitor kit! But I can also try another one again.
Unfortunately, I can't test it, I would have to send it back to my computer specialist. He's got an oscilloscope.

First I test with a different PSU and without connections.
Can I also use a multimeter to test which voltages are present on the clock patch? I would have that there. Sorry I don't have the experience!

Recap won't solve every PSU problem. So worth trying a second. You can't check signals with multimeter...

If you wanted to get to the bottom of it all, I could take a look if you send me your motherboard if you pay for return postage. Of course I cannot guarantee anything but I think this tends to be a common problem on falcons,so think it would help if the issue could be found, and if its a simple fix or not..

[kohli79]

The power supply is recapted with your capacitor kit! But I can also try another one again.
Unfortunately, I can't test it, I would have to send it back to my computer specialist. He's got an oscilloscope.

First I test with a different PSU and without connections.
Can I also use a multimeter to test which voltages are present on the clock patch? I would have that there. Sorry I don't have the experience!

Recap won't solve every PSU problem. So worth trying a second. You can't check signals with multimeter...

If you wanted to get to the bottom of it all, I could take a look if you send me your motherboard if you pay for return postage. Of course I cannot guarantee anything but I think this tends to be a common problem on falcons,so think it would help if the issue could be found, and if its a simple fix or not..

We can try that and would be happy! Postage is not a problem, I pay of course ...
I'll be shipping next week (tomorrow is a public holiday in Germany), I still need the address for that. Thanks again for the help, I want it to work again.

[exxos]

This machine just arrived

It's a bit odd as after about 10 mins it starts to go nuts...

IMG_6501.JPG (104.19 KiB) Viewed 4491 times

It seems one of the clock lines is not happy and needs a 100K resistor on it to keep it happy.. Easy fix..

IMG_6502.JPG (88.51 KiB) Viewed 4491 times

So onto the sound stuff...

This is with nothing plugged in the audio jack..

IMG_6503.JPG (54.05 KiB) Viewed 4491 times

If I put my headphones in and change the volume control ( on the headphones it is very noisy pot) it generates this below..

IMG_6504.JPG (60.02 KiB) Viewed 4491 times

[exxos]

@kohli79 Said the audio would malfunction after just 30 seconds.. so this was running for 6 mins..




Also will leave DMA2DSP.PRG running for some more hours...

The machine has been on almost a hour already now...

IMG_6506.JPG (84.65 KiB) Viewed 4477 times

[kohli79]

@kohli79 Said the audio would malfunction after just 30 seconds.. so this was running for 6 mins..
Also will leave DMA2DSP.PRG running for some more hours...

The machine has been on almost a hour already now...

Incredible!
Exxos is the best!

[exxos]

It's been drawing green for almost 2 hours now, so will try it again tomorrow to make sure the same thing happens

[Steve]

@exxos for educational purposes could you please describe how you realised the clock line needed that resistor, and as a side note do you have any idea why this falcon might be different to others? Thx

[exxos]

Exxos for educational purposes could you please describe how you realised the clock line needed that resistor,

I used the best diagnostic tool available,"finger on board" = works

and as a side note do you have any idea why this falcon might be different to others? Thx

It's just "dumb luck" with this stuff. Its very hard to design a "one size fits all" fix for machines when every Falcon has different odd quirks with it. Now I am aware of this issue I will update my website to mention it as it may help others in future.

My clock board needs some small loading to function correctly (hence adding the 100K) but normally the SDMA is enough to load it and things are happy. On this Falcon, nope. For some reason it's not enough. Signal just looks bad, lots of ringing, The voltage if I remember rightly looks higher on the clock than it would ordinarily be as well. Could be some slight harmonic resonance going on somewhere around 100mhz. It could just be this board inherently more noise problems. Though this resistor is only relevant to my clock board anyway. It won't help just adding 100K on it on any other clock boards.

Unfortunately these things are a lot of guesswork. I mean if I had personally fitted and tested a batch of 1,000 Falcons, then a lot more would be learned and diagnosed right at the start.. But of course such things cannot happen. So I really have to make best guesses on how to fix problems, so it is just inevitable that every now and again a Falcon will malfunction.

The clock patch has solved the original noise problems in any case. Just this Falcon needed some a bit extra to get it to behave. #WelcomeToAtari

[Steve]

Thanks