bostonvintage1993 wrote on 2022-12-30, 18:57:

Hi all,

I have a motherboard (photo attached) with a Cyrix MediaGX processor. I have been able to find absolutely no information on the motherboard. I have gotten it to POST with the traditional power connector (picture shown) but I want to put the motherboard in an ATX case. I have plugged in the ATX power connector, but then (as I show in the attached photos) I have no clue how to attach this connector to the appropriate header on the motherboard. I’d like to find out more information about this board. How can I get this motherboard to boot with an ATX power supply? Thank you so much for any help you can provide!

According to the bios string, it seems to be a DataExpert MGX7520...

https://web.archive.org/web/19981203044142/ht … rix/mgx7520.htm

https://theretroweb.com/motherboards/s/dataex … mgx7520-baby-at

...but with both AT & ATX power connectors - at the 2nd link above (downloads > jumper manual) it suggests ATX soft power is on pins 10 & 11 of the JP7 jumper block.

You seem to be on the latest v2.0 bios, but you'll find some vga / sound drivers here (first two links only) - https://web.archive.org/web/20020220124454/ht … R/MB/D7520.html

PC Hoarder Patrol wrote on 2022-12-30, 22:19:

According to the bios string, it seems to be a DataExpert MGX7520... […]
Show full quote

bostonvintage1993 wrote on 2022-12-30, 18:57:

Hi all,

I have a motherboard (photo attached) with a Cyrix MediaGX processor. I have been able to find absolutely no information on the motherboard. I have gotten it to POST with the traditional power connector (picture shown) but I want to put the motherboard in an ATX case. I have plugged in the ATX power connector, but then (as I show in the attached photos) I have no clue how to attach this connector to the appropriate header on the motherboard. I’d like to find out more information about this board. How can I get this motherboard to boot with an ATX power supply? Thank you so much for any help you can provide!

According to the bios string, it seems to be a DataExpert MGX7520...

https://web.archive.org/web/19981203044142/ht … rix/mgx7520.htm

https://theretroweb.com/motherboards/s/dataex … mgx7520-baby-at

...but with both AT & ATX power connectors - at the 2nd link above (downloads > jumper manual) it suggests ATX soft power is on pins 10 & 11 of the JP7 jumper block.

You seem to be on the latest v2.0 bios, but you'll find some vga / sound drivers here (first two links only) - https://web.archive.org/web/20020220124454/ht … R/MB/D7520.html

Thanks for the reply! This is really helpful - is there any chance you could diagram exactly where I need to place my connector on the header from the photo? I seem to only have twenty pins. I’m still confused on where it should go. Thank you so much!

bostonvintage1993 wrote on 2022-12-30, 22:41:

PC Hoarder Patrol wrote on 2022-12-30, 22:19:

According to the bios string, it seems to be a DataExpert MGX7520... […]
Show full quote

bostonvintage1993 wrote on 2022-12-30, 18:57:

Hi all,

I have a motherboard (photo attached) with a Cyrix MediaGX processor. I have been able to find absolutely no information on the motherboard. I have gotten it to POST with the traditional power connector (picture shown) but I want to put the motherboard in an ATX case. I have plugged in the ATX power connector, but then (as I show in the attached photos) I have no clue how to attach this connector to the appropriate header on the motherboard. I’d like to find out more information about this board. How can I get this motherboard to boot with an ATX power supply? Thank you so much for any help you can provide!

According to the bios string, it seems to be a DataExpert MGX7520...

https://web.archive.org/web/19981203044142/ht … rix/mgx7520.htm

https://theretroweb.com/motherboards/s/dataex … mgx7520-baby-at

...but with both AT & ATX power connectors - at the 2nd link above (downloads > jumper manual) it suggests ATX soft power is on pins 10 & 11 of the JP7 jumper block.

You seem to be on the latest v2.0 bios, but you'll find some vga / sound drivers here (first two links only) - https://web.archive.org/web/20020220124454/ht … R/MB/D7520.html

Thanks for the reply! This is really helpful - is there any chance you could diagram exactly where I need to place my connector on the header from the photo? I seem to only have twenty pins. I’m still confused on where it should go. Thank you so much!

On second reading, your JP7 pin block (2 x 10) differs from that shown in the link (2 x 12), so the quoted pins 10 & 11 are probably wrong for this board version. However, the silkscreen printing on your board does seem to suggest that the 2 two pins shown below in red are reset (RST) and the two in green are ATX power (PSW) - so without attaching your connector, plug in your ATX power supply and short the two green pins together momentarily with a screwdriver (does the board boot?) then do the same with the two red pins (does the board reboot?)

PC Hoarder Patrol wrote on 2022-12-31, 01:31:

bostonvintage1993 wrote on 2022-12-30, 22:41:

PC Hoarder Patrol wrote on 2022-12-30, 22:19:

According to the bios string, it seems to be a DataExpert MGX7520... […]
Show full quote

According to the bios string, it seems to be a DataExpert MGX7520...

https://web.archive.org/web/19981203044142/ht … rix/mgx7520.htm

https://theretroweb.com/motherboards/s/dataex … mgx7520-baby-at

...but with both AT & ATX power connectors - at the 2nd link above (downloads > jumper manual) it suggests ATX soft power is on pins 10 & 11 of the JP7 jumper block.

You seem to be on the latest v2.0 bios, but you'll find some vga / sound drivers here (first two links only) - https://web.archive.org/web/20020220124454/ht … R/MB/D7520.html

Thanks for the reply! This is really helpful - is there any chance you could diagram exactly where I need to place my connector on the header from the photo? I seem to only have twenty pins. I’m still confused on where it should go. Thank you so much!

On second reading, your JP7 pin block (2 x 10) differs from that shown in the link (2 x 12), so the quoted pins 10 & 11 are probably wrong for this board version. However, the silkscreen printing on your board does seem to suggest that the 2 two pins shown below in red are reset (RST) and the two in green are ATX power (PSW) - so without attaching your connector, plug in your ATX power supply and short the two green pins together momentarily with a screwdriver (does the board boot?) then do the same with the two red pins (does the board reboot?)

MGX7520 FP Header.jpg

Hi,

Yes, the screwdriver worked! However, when I went to plug in the connector it would not power on, and now the screwdriver also does not power on the motherboard. Any idea what went wrong? Any help would be greatly appreciated! Thank you for your help so far!

bostonvintage1993 wrote on 2022-12-31, 15:38:

PC Hoarder Patrol wrote on 2022-12-31, 01:31:

bostonvintage1993 wrote on 2022-12-30, 22:41:

Thanks for the reply! This is really helpful - is there any chance you could diagram exactly where I need to place my connector on the header from the photo? I seem to only have twenty pins. I’m still confused on where it should go. Thank you so much!

On second reading, your JP7 pin block (2 x 10) differs from that shown in the link (2 x 12), so the quoted pins 10 & 11 are probably wrong for this board version. However, the silkscreen printing on your board does seem to suggest that the 2 two pins shown below in red are reset (RST) and the two in green are ATX power (PSW) - so without attaching your connector, plug in your ATX power supply and short the two green pins together momentarily with a screwdriver (does the board boot?) then do the same with the two red pins (does the board reboot?)

MGX7520 FP Header.jpg

Hi,

Yes, the screwdriver worked! However, when I went to plug in the connector it would not power on, and now the screwdriver also does not power on the motherboard. Any idea what went wrong? Any help would be greatly appreciated! Thank you for your help so far!

Unless the connector wring matched the pins I marked, it was never going to work - detail (with pics) which connector wire goes to which position on the connector, their function (if you know it) and how you plugged it into the board pin header. Maybe you shorted something by doing so? Does the board still power on when using the traditional AT power connector?

Gotta be careful with those front panel headers. Sometimes you can fry the power button or board all together.

PC Hoarder Patrol wrote on 2023-01-01, 02:02:

bostonvintage1993 wrote on 2022-12-31, 15:38:

PC Hoarder Patrol wrote on 2022-12-31, 01:31:

On second reading, your JP7 pin block (2 x 10) differs from that shown in the link (2 x 12), so the quoted pins 10 & 11 are probably wrong for this board version. However, the silkscreen printing on your board does seem to suggest that the 2 two pins shown below in red are reset (RST) and the two in green are ATX power (PSW) - so without attaching your connector, plug in your ATX power supply and short the two green pins together momentarily with a screwdriver (does the board boot?) then do the same with the two red pins (does the board reboot?)

MGX7520 FP Header.jpg

Hi,

Yes, the screwdriver worked! However, when I went to plug in the connector it would not power on, and now the screwdriver also does not power on the motherboard. Any idea what went wrong? Any help would be greatly appreciated! Thank you for your help so far!

Unless the connector wring matched the pins I marked, it was never going to work - detail (with pics) which connector wire goes to which position on the connector, their function (if you know it) and how you plugged it into the board pin header. Maybe you shorted something by doing so? Does the board still power on when using the traditional AT power connector?

Hi,

Thanks again for the help. The board does still power on with the traditional AT connector. Here is the exact configuration I used on the board, and another picture of the connector for reference. I wired the connector the way I thought it should go. Blue and black together are the power button wires. The white and black wires at the end of the connector are for the reset button but I don’t plan to use them so that’s why I put them on the outside. The green and yellow wires are for the power led, and the blue and red wires are for the hdd led. I wired it up to what I thought corresponded to the board, but then it wouldn’t power on anymore and now I can’t get it to go. Any advice would be greatly appreciated. Thank you.

From motherboard's front to back.

I reset, I power, I stand by switch, I stand by sleep LED, I hard drive LED. _ pin 1 and 4 is speaker, _ pin 1 and 3 power led and pin 4 and 5 keylock.

I means across two pins. _ means oriented to front and back.

Cheers,

pentiumspeed wrote on 2023-01-01, 22:11:

From motherboard's front to back. […]
Show full quote

From motherboard's front to back.

I reset, I power, I stand by switch, I stand by sleep LED, I hard drive LED. _ pin 1 and 4 is speaker, _ pin 1 and 3 power led and pin 4 and 5 keylock.

I means across two pins. _ means oriented to front and back.

Cheers,

Hi,

Thanks for the info. I unfortunately still can’t get the board to power on anymore using ATX power. Like I said, when I plugged in the connector I had rearranged the board turned on but then turned off quickly, and now I can’t get it to power back on using the screwdriver trick. What can I do to get the board back using ATX?

Let me know, thanks.

bostonvintage1993 wrote on 2023-01-04, 20:32:

Hi, […]
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pentiumspeed wrote on 2023-01-01, 22:11:

From motherboard's front to back. […]
Show full quote

From motherboard's front to back.

I reset, I power, I stand by switch, I stand by sleep LED, I hard drive LED. _ pin 1 and 4 is speaker, _ pin 1 and 3 power led and pin 4 and 5 keylock.

I means across two pins. _ means oriented to front and back.

Cheers,

Hi,

Thanks for the info. I unfortunately still can’t get the board to power on anymore using ATX power. Like I said, when I plugged in the connector I had rearranged the board turned on but then turned off quickly, and now I can’t get it to power back on using the screwdriver trick. What can I do to get the board back using ATX?

Let me know, thanks.

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g.

- power on board by shorting two pins (OK)
- power off board by shorting same two pins, either momentarily or 4 sec hold (?)
- reset powered on board using other two pins (?)
- repeat any of the above steps (?)

Your connector re-wiring looks OK, though clearly something has changed since the first shorting trial - have you tried a complete CMOS reset or coin battery removal incase its BIOS related?

PC Hoarder Patrol wrote on 2023-01-04, 20:45:

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g. […]
Show full quote

bostonvintage1993 wrote on 2023-01-04, 20:32:

Hi, […]
Show full quote

pentiumspeed wrote on 2023-01-01, 22:11:

From motherboard's front to back. […]
Show full quote

From motherboard's front to back.

I reset, I power, I stand by switch, I stand by sleep LED, I hard drive LED. _ pin 1 and 4 is speaker, _ pin 1 and 3 power led and pin 4 and 5 keylock.

I means across two pins. _ means oriented to front and back.

Cheers,

Hi,

Thanks for the info. I unfortunately still can’t get the board to power on anymore using ATX power. Like I said, when I plugged in the connector I had rearranged the board turned on but then turned off quickly, and now I can’t get it to power back on using the screwdriver trick. What can I do to get the board back using ATX?

Let me know, thanks.

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g.

- power on board by shorting two pins (OK)
- power off board by shorting same two pins, either momentarily or 4 sec hold (?)
- reset powered on board using other two pins (?)
- repeat any of the above steps (?)

Your connector re-wiring looks OK, though clearly something has changed since the first shorting trial - have you tried a complete CMOS reset or coin battery removal incase its BIOS related?

Hi,

When I initially got the board started I just powered on the board by shorting two pins. Then, I unplugged the power and rewired the connector. I plugged the connector onto the motherboard and then the board turned on for a split second before turning off. Now, I can’t get the power to power on at all with the screwdriver trick. I can only get it to power on with traditional AT power. The only thing that could’ve possible changed from when I first got the board working to now is my rewired connector, but I don’t see how that could’ve shorted the board. As always, any advice you can give would be very helpful.

bostonvintage1993 wrote on 2023-01-05, 20:20:

PC Hoarder Patrol wrote on 2023-01-04, 20:45:

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g. […]
Show full quote

bostonvintage1993 wrote on 2023-01-04, 20:32:

Hi,

Thanks for the info. I unfortunately still can’t get the board to power on anymore using ATX power. Like I said, when I plugged in the connector I had rearranged the board turned on but then turned off quickly, and now I can’t get it to power back on using the screwdriver trick. What can I do to get the board back using ATX?

Let me know, thanks.

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g.

- power on board by shorting two pins (OK)
- power off board by shorting same two pins, either momentarily or 4 sec hold (?)
- reset powered on board using other two pins (?)
- repeat any of the above steps (?)

Your connector re-wiring looks OK, though clearly something has changed since the first shorting trial - have you tried a complete CMOS reset or coin battery removal incase its BIOS related?

Hi,

When I initially got the board started I just powered on the board by shorting two pins. Then, I unplugged the power and rewired the connector. I plugged the connector onto the motherboard and then the board turned on for a split second before turning off. Now, I can’t get the power to power on at all with the screwdriver trick. I can only get it to power on with traditional AT power. The only thing that could’ve possible changed from when I first got the board working to now is my rewired connector, but I don’t see how that could’ve shorted the board. As always, any advice you can give would be very helpful.

Now that I've seen a board manual (albeit not for your exact power header / pin block layout), my first guess was a bit out!...try the one in the pic below, so you're following the bottom 20 pin colour coded version (the top version is straight from the manual), by shorting the two green pins (17 & 18) to test power on and then the two red pins (19 & 20) to test reset, and report back.

That's the one I'm saying all along.

Cheers,

PC Hoarder Patrol wrote on 2023-01-07, 04:21:

bostonvintage1993 wrote on 2023-01-05, 20:20:

PC Hoarder Patrol wrote on 2023-01-04, 20:45:

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g. […]
Show full quote

When you got the board started, by shorting the two pins, how much 'testing' did you do e.g.

- power on board by shorting two pins (OK)
- power off board by shorting same two pins, either momentarily or 4 sec hold (?)
- reset powered on board using other two pins (?)
- repeat any of the above steps (?)

Your connector re-wiring looks OK, though clearly something has changed since the first shorting trial - have you tried a complete CMOS reset or coin battery removal incase its BIOS related?

Hi,

When I initially got the board started I just powered on the board by shorting two pins. Then, I unplugged the power and rewired the connector. I plugged the connector onto the motherboard and then the board turned on for a split second before turning off. Now, I can’t get the power to power on at all with the screwdriver trick. I can only get it to power on with traditional AT power. The only thing that could’ve possible changed from when I first got the board working to now is my rewired connector, but I don’t see how that could’ve shorted the board. As always, any advice you can give would be very helpful.

Now that I've seen a board manual (albeit not for your exact power header / pin block layout), my first guess was a bit out!...try the one in the pic below, so you're following the bottom 20 pin colour coded version (the top version is straight from the manual), by shorting the two green pins (17 & 18) to test power on and then the two red pins (19 & 20) to test reset, and report back.

MGX7520 FP Header V2.jpg

Thanks for the diagrams! However, I shorted those exact pins and still no luck. I can no longer get the board to turn on at all with ATX, only with AT. I don’t understand how I could’ve shorted the connector. Like I said previously, I only put the newly wired connector in there and then everything stopped working.

I’m at a loss as to what to do next.

There are little chips next to these pin headers usually one probably got shorted.

You could try to replace them

Perhaps it is one of the transistors?

Sphere478 wrote on 2023-01-08, 16:46:

There are little chips next to these pin headers usually one probably got shorted.

You could try to replace them

Perhaps it is one of the transistors?

Thanks for the suggestion! I unfortunately don't see any socketed chips and don't really have the skills/tools to test/replace soldered-in chips. It's a shame I can't get this board to work with ATX. I almost had it! I have no clue how it could've shorted.

At least it still works with the traditional AT connector. Not sure what to do with this motherboard now... as I really wanted to use it in the ATX case 🙁

Sphere478 wrote on 2023-01-08, 16:46:

There are little chips next to these pin headers usually one probably got shorted.

You could try to replace them

Perhaps it is one of the transistors?

Hello everyone,

I’ve returned to this board and I’ve done some testing. When I power on the board using the AT power connector, I can get the reset button to work and the power led to work right off of the connector on the board. I just can’t seem to get the board to power on using ATX, and I’m not sure why! If the connector was shorted, then the power led and reset button wouldn’t work under AT power, right?

I could really use some help, thanks!

Keep in mind:

AT is what cause the motherboard reset circuits to operate at start up via POWER GOOD signal from AT power supply moment after AT power supply's own power switch is thrown on.

ATX power supply have one more signal pin that board need to ground low and kept low as to turn ATX power supply on when momentary button is pushed once via motherboard's power switch, then POWER GOOD is pulled high that causes the motherboard to reset the motherboard once to known state before CPU starts executing. While motherboard is on, the power signal must be kept grounded till either one of two conditions: select power off icon by mouse or hold the power button in for 5 seconds then this power singal is allowed to float high thus ATX power supply turns off.

Another feature of the ATX and motherboard's power button is holding the button in for 5 seconds powers the board off. Using ATX with this motherboard you only need to momentarily short power switch two pins together just once to turn on.

Momentary button is normally open, that closes a circuit (switch closed) when you press the button and is open again as button is released.

Keep in mind.

Cheers,

pentiumspeed wrote on 2023-02-12, 00:24:

Keep in mind: […]
Show full quote

Keep in mind:

AT is what cause the motherboard reset circuits to operate at start up via POWER GOOD signal from AT power supply moment after AT power supply's own power switch is thrown on.

ATX power supply have one more signal pin that board need to ground low and kept low as to turn ATX power supply on when momentary button is pushed once via motherboard's power switch, then POWER GOOD is pulled high that causes the motherboard to reset the motherboard once to known state before CPU starts executing. While motherboard is on, the power signal must be kept grounded till either one of two conditions: select power off icon by mouse or hold the power button in for 5 seconds then this power singal is allowed to float high thus ATX power supply turns off.

Another feature of the ATX and motherboard's power button is holding the button in for 5 seconds powers the board off. Using ATX with this motherboard you only need to momentarily short power switch two pins together just once to turn on.

Momentary button is normally open, that closes a circuit (switch closed) when you press the button and is open again as button is released.

Keep in mind.

Cheers,

Thanks for the information about ATX. I have tried shorting the two pins for the power button momentarily, to no success. Any idea why it’s not working? I don’t believe the connector is faulty since it works fine under AT power.

Let me know, thanks.