Author Topic: Fixing RGB output from a X68000 XVI  (Read 6257 times)

Offline thorias

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Fixing RGB output from a X68000 XVI
« on: July 09, 2012, 02:09:08 am »
Hi all!

I'm the proud owner of a X68000 XVI, which is working perfectly fine. But being tired to be limited to 31Khz games, I got an chinese converter board called GBS 8220 which have kind of VGA input with two vga output, was expecting it to convert directly 15Khz to 31Khz Vsync as per its manual/specs, I plug everything together: X68000->vga cable->GBS 8220 input-> vga cable-> my lcd vga monitor....Switch on everything, got the converter menu on my vga lcd screen, but nothing from the X68000 (lcd screen says no input) played with the converter menus and check everything again same. Well connect back the X68000 direct to the lcd screen, no picture!! monitor was switching on/off/on/off damn, this thing killed something!!  >:(
dismantle the X68000 mobo and rgb out and after troubleshooting I figured out that pin 2 on the SN74ALS05AN have a bad output (both Hsync and Vsync signals go directly to the SN74ALS05AN from RGB output pin 14 and 15), it is a HEX INVERTERS WITH OPEN-COLLECTOR OUTPUTS, it is located next to the white onboard RGB connector and there is only one type of this component out of the entire mobo so you can't miss it!!!.

Bought 5 of them and at the same time a 14 pins DIP round pin socket, removed old component from mobo solder the 14 pin DIP socket (in case if something happen again easier to change out!! hope no!!  :P), put brand new SN74ALS05AN, put back everything together and tadaaa picture was back on my lcd screen!! I was so happy!!

This is just to share my experience with you guys as I saw other people had a similar issue with connecting some LCD TV and having lost their RGB output.

Sorry didn't took any pictures but these below will help you.




« Last Edit: July 10, 2012, 08:04:41 am by thorias »

Offline eidis

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Re: Fixing RGB output from a X68000 XVI
« Reply #1 on: July 09, 2012, 07:30:04 am »
 Hi Thorias !

 This is a very good tutorial and thank you for sharing it with us. The repair division is growing :)

Eidis
X68000 personal computer is called, "X68K" or "no good good" is called, is the PC that are loved by many people today.

Offline Nelsinho

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Re: Fixing RGB output from a X68000 XVI
« Reply #2 on: July 10, 2012, 10:42:17 am »
Very nice!
Thank you for share ! ;D

Offline Lawrence

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Re: Fixing RGB output from a X68000 XVI
« Reply #3 on: July 10, 2012, 06:53:20 pm »
Front page!

Good work, thorias.  =)

Offline thorias

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Re: Fixing RGB output from a X68000 XVI
« Reply #4 on: July 12, 2012, 10:01:52 am »
Humm! Nice thank you!! Later on will give some nice interesting stuff about X68000...stay tuned!  :P
« Last Edit: July 12, 2012, 10:03:52 am by thorias »

Offline doubleflash

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Re: Fixing RGB output from a X68000 XVI
« Reply #5 on: July 13, 2012, 09:44:31 pm »
Thanks for the manual, i have the same error on a x68000 expert, v-sync never reached the monitor, after a change it shows me a picture again

greetz Doubleflash
Evil Mad Science always win

Offline thorias

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Re: Fixing RGB output from a X68000 XVI
« Reply #6 on: July 14, 2012, 08:32:04 pm »
Thanks for the manual, i have the same error on a x68000 expert, v-sync never reached the monitor, after a change it shows me a picture again

greetz Doubleflash

Cool I'm happy that you fixed it!! one more X68000 alive!!  :D

Offline stt1

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Re: Fixing RGB output from a X68000 XVI
« Reply #7 on: September 17, 2012, 09:10:57 am »
Sidenote:

If you have X68030 and it's missing the picture on screen. Try first changing the caps on video board. I encountered once a twin-tower which did not have other problems than worn caps (debugged with another video board, which worked just fine - after changing caps all was fine again with the other as well)...

- Saku

Offline DustyBits

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Re: Fixing RGB output from a X68000 XVI
« Reply #8 on: July 18, 2013, 09:04:54 pm »
Hi all!

I'm the proud owner of a X68000 XVI, which is working perfectly fine. But being tired to be limited to 31Khz games, I got an chinese converter board called GBS 8220 which have kind of VGA input with two vga output, was expecting it to convert directly 15Khz to 31Khz Vsync as per its manual/specs, I plug everything together: X68000->vga cable->GBS 8220 input-> vga cable-> my lcd vga monitor....Switch on everything, got the converter menu on my vga lcd screen, but nothing from the X68000 (lcd screen says no input) played with the converter menus and check everything again same. Well connect back the X68000 direct to the lcd screen, no picture!! monitor was switching on/off/on/off damn, this thing killed something!!  >:(
dismantle the X68000 mobo and rgb out and after troubleshooting I figured out that pin 2 on the SN74ALS05AN have a bad output (both Hsync and Vsync signals go directly to the SN74ALS05AN from RGB output pin 14 and 15), it is a HEX INVERTERS WITH OPEN-COLLECTOR OUTPUTS, it is located next to the white onboard RGB connector and there is only one type of this component out of the entire mobo so you can't miss it!!!.

Bought 5 of them and at the same time a 14 pins DIP round pin socket, removed old component from mobo solder the 14 pin DIP socket (in case if something happen again easier to change out!! hope no!!  :P), put brand new SN74ALS05AN, put back everything together and tadaaa picture was back on my lcd screen!! I was so happy!!

This is just to share my experience with you guys as I saw other people had a similar issue with connecting some LCD TV and having lost their RGB output.

Sorry didn't took any pictures but these below will help you.






Hi there ...

I have a X68k compact :-)

But the same error - black screen :-(

But my problem - no sn74als05 on the whole mainboard :-) I need a little help :-)

Offline lydux

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Re: Fixing RGB output from a X68000 XVI
« Reply #9 on: July 18, 2013, 09:43:49 pm »
Hi DustyBits,

On Compact XVI models, the sync inverter is IC118 (a 74ALS04), located on the back of the motherboard.

Let us know if that fix your problem !


Offline DustyBits

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Re: Fixing RGB output from a X68000 XVI
« Reply #10 on: July 19, 2013, 03:43:25 am »
Hi DustyBits,

On Compact XVI models, the sync inverter is IC118 (a 74ALS04), located on the back of the motherboard.

Let us know if that fix your problem !

Thanks !!! :-) I will try to replace this IC :-) Thanks for your support !!! :-)

Offline DustyBits

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Re: Fixing RGB output from a X68000 XVI
« Reply #11 on: July 30, 2013, 12:50:06 am »
Hi DustyBits,

On Compact XVI models, the sync inverter is IC118 (a 74ALS04), located on the back of the motherboard.

Let us know if that fix your problem !


THX ... video out is now in function again...


BIG THX

Offline BlueBMW

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Re: Fixing RGB output from a X68000 XVI
« Reply #12 on: July 30, 2013, 01:51:09 am »
Do you guys thing this hex inverter should be replaced as a preventive measure or just wait til it fails?

Offline lydux

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Re: Fixing RGB output from a X68000 XVI
« Reply #13 on: July 30, 2013, 07:25:57 am »
Quote
THX ... video out is now in function again...

BIG THX

Thank for the report !

Quote
Do you guys thing this hex inverter should be replaced as a preventive measure or just wait til it fails?
It seems to me to be a possible common failure for every x68000 models ! Not really surprising as it's an highly solicited IC...
I think while you are at replacing capacitors or doing any kind of maintenance involving the main board, it will not hurt changing it for prevention.