VOGONS


Reply 80 of 237, by Yvan256

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Jepael wrote:

It is a bit difficult to find info, but some sources say the Sound Master has a DAC and it supports DMA for the DAC, so the PAL chip would be handling DMA protocol. Now, I can't find any timebase chip to trigger DMA transactions, so you guys with the schematics can re-post it or figure out if the sampling rate is fixed or somehow selectable.

I'll have to fetch up the programming manual. You guys also have it... right?

Reply 81 of 237, by carlostex

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Yvan256 wrote:

I'll have to fetch up the programming manual. You guys also have it... right?

I can only speak for myself, AFAIK no one here in vogons has any kind of Sound Master documentation. I have never found anything digitally on the web either.

Reply 82 of 237, by Yvan256

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carlostex wrote:
Yvan256 wrote:

I'll have to fetch up the programming manual. You guys also have it... right?

I can only speak for myself, AFAIK no one here in vogons has any kind of Sound Master documentation. I have never found anything digitally on the web either.

I guess that's something else I will have to scan.

Reply 83 of 237, by bristlehog

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If there is a programming manual, I could try and make MIDI drivers for this, provided that I have a card exemplar (or some means of emulation) to test on.

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Reply 84 of 237, by Stiletto

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Yvan256 wrote:
carlostex wrote:
Yvan256 wrote:

I'll have to fetch up the programming manual. You guys also have it... right?

I can only speak for myself, AFAIK no one here in vogons has any kind of Sound Master documentation. I have never found anything digitally on the web either.

I guess that's something else I will have to scan.

Did some quick looking around online and it's not leaping out at me, so yes this would be appreciated, thanks!

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Reply 85 of 237, by Fagear

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I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse.
1052198.jpg

Awful layout. And lots of traces are invisible under ICs. But still, I didn't finished with all visible traces yet. And a GAL/PAL device is a bit of concern...

New BIG soundcard: FMonster.
Covox Sound Master replica
Innovation SSI-2001 replica & DuoSID.
My audio/video collection.

Reply 86 of 237, by Yvan256

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Fagear wrote:
I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse. http://fotkidepo.ru/photo/229919/ […]
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I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse.
1052198.jpg

Awful layout. And lots of traces are invisible under ICs. But still, I didn't finished with all visible traces yet. And a GAL/PAL device is a bit of concern...

I don't have much time on my side either at the moment, but I'll make a list of all the resistors values, transistor numbers, etc.

As for that GAL, by seeing where it is connected to maybe we can deduce its function.

Reply 87 of 237, by carlostex

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Fagear wrote:
I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse. http://fotkidepo.ru/photo/229919/ […]
Show full quote

I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse.
1052198.jpg

Awful layout. And lots of traces are invisible under ICs. But still, I didn't finished with all visible traces yet. And a GAL/PAL device is a bit of concern...

What would be the normal procedure to figure out the hidden traces? Desoldering the IC's?

Reply 88 of 237, by awgamer

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carlostex wrote:
Fagear wrote:
I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse. http://fotkidepo.ru/photo/229919/ […]
Show full quote

I'm slowly getting there... I have not much time to do this and PCB is really hard to reverse.
1052198.jpg

Awful layout. And lots of traces are invisible under ICs. But still, I didn't finished with all visible traces yet. And a GAL/PAL device is a bit of concern...

What would be the normal procedure to figure out the hidden traces? Desoldering the IC's?

That's what I'd do.

Reply 89 of 237, by Fagear

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awgamer wrote:

That's what I'd do.

That's the "destructive way". Of course you can solder everything back, but you can damage PCB or parts in process.
First, we need to try another way.
Light some light through the board, look at shallow angles under ICs, check some assumptions with multimeter continuity test.

1052306.jpg 1052307.jpg

New BIG soundcard: FMonster.
Covox Sound Master replica
Innovation SSI-2001 replica & DuoSID.
My audio/video collection.

Reply 90 of 237, by carlostex

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Fagear wrote:
That's the "destructive way". Of course you can solder everything back, but you can damage PCB or parts in process. First, we ne […]
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That's the "destructive way". Of course you can solder everything back, but you can damage PCB or parts in process.
First, we need to try another way.
Light some light through the board, look at shallow angles under ICs, check some assumptions with multimeter continuity test.

1052306.jpg 1052307.jpg

To be honest i thought about light too, and with the images you posted make the traces really visible. But since the design of the Covox was a bit of a mess, i was wondering how difficult it would be even with the light.

We'll have to wait until Yvan can do that. Maybe he can put some light under the card each side and then take some pics again. Maybe after we can speculate or figure out what is the GAL actually doing.

Reply 91 of 237, by Yvan256

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Here's the best I can do at the moment, without a scanner.

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Reply 92 of 237, by bristlehog

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carlostex wrote:

What would be the normal procedure to figure out the hidden traces? Desoldering the IC's?

I have heard that X-Ray can be used to detect the hidden traces. Not sure though if X-Ray is harmful to electronic components.

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Reply 93 of 237, by Jepael

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bristlehog wrote:

I have heard that X-Ray can be used to detect the hidden traces. Not sure though if X-Ray is harmful to electronic components.

If it was harmful, we would have broken laptops and cell phones after airport security. X-ray is also used for inspecting bad solder joints under chips.

I know it is annoying and slow, but if no other equipment is available, it can be done by just looking at the PCB real hard and using multimeter. Light helps, especially with cards that have only two layers and no solid planes so light can pass it easily.

I do not suggest using multimeter in continuity test mode, as it will beep if the resistance is just under some largish threshold.
It is better to have it in resistance measurement mode and see for yourself if the measured resistance is same than just connecting the wires together.
Otherwise it will beep sometimes even if traces are not connected together, but through some component.
(OK, continuity test beep mode is fine if all components are removed, but I don't suggest that either).

Sometimes if it is hard to see, it is possible to make a good guess where traces are connected, and verify the guess with multimeter. For example, an output from a chip is connected to one or more inputs of another chips (there are exceptions if they are open collector outputs) etc.

Edit: On a side note, did anyone have a link to the programming manual? It might help figuring out the hardware as well.

Reply 94 of 237, by Yvan256

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Jepael wrote:

On a side note, did anyone have a link to the programming manual? It might help figuring out the hardware as well.

I have the original programming manual, once I have access to a scanner I'll scan it.

Reply 95 of 237, by vetz

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Yvan256 wrote:
Jepael wrote:

On a side note, did anyone have a link to the programming manual? It might help figuring out the hardware as well.

I have the original programming manual, once I have access to a scanner I'll scan it.

if you have problems getting it to a scanner, taking pictures with a newer smartphone also works very well 😀

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Reply 96 of 237, by Fagear

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Yvan256 wrote:

Here's the best I can do at the moment, without a scanner.

Thanks, but it doesn't give much more information. Shallow angle and better focused image would help.

Now I copied almost every visible track (not including filled polygons). And wrote down values of all resistors.
1053463.jpg

New BIG soundcard: FMonster.
Covox Sound Master replica
Innovation SSI-2001 replica & DuoSID.
My audio/video collection.

Reply 97 of 237, by carlostex

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Fagear wrote:
Thanks, but it doesn't give much more information. Shallow angle and better focused image would help. […]
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Thanks, but it doesn't give much more information. Shallow angle and better focused image would help.

Now I copied almost every visible track (not including filled polygons). And wrote down values of all resistors.
1053463.jpg

Amazing work Fagear. 😎

Reply 98 of 237, by carlostex

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Good news!

I contacted Nick Skrepetos on facebook a few months ago. I was not sure he was the Nick Skrepetos who worked for Covox but since this person was from Eugene, Oregon i thought it was worth the shot.

Well he replied to me yesterday, confirming he is the Nick Skrepetos who worked for Covox. I sent him a message again asking for whatever help he can give to us to this project, so let's hope for the best. He did software at Covox if i'm not mistaken, but maybe he can also give us a hand to maybe figure out faster what that GAL is actually doing, or better yet, get the correct logic and be done with it.

Stay tuned.

Reply 99 of 237, by shock__

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Nice effort!
Don't expect too much tho, I managed to find the guy who designed the SSI-2001 who actually promised me schemes & docs ... and possibly a card. After a year of "I didn't get to check yet" I stopped asking. That was a bit less than 4 years ago.

Current Project: new GUS PnP compatible soundcard

[Z?]