386sx sometimes boots in mono. \ VOGONS

386sx sometimes boots in mono.

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First post, by flynth

Posted on 2022-11-11, 13:42

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I'm in a process of setting up a 386sx-25 system. However I'm having a weird issue. The system sometimes runs fine, other times it boots in mono. One just has to try many times then to get color again.

My motherboard has a mono/color jumper. I replaced it. I also tried scratching through any possible corrosion on the pins by repeatedly removing and installing the jumper. This made no difference.

The video card is trident 9000. It has no mono/color selection. It does however have one jumper I'm not sure how works. It is the "bios auto detect configuration" jumper. Could it being on enable have anything to do with this?

I tried wiggling the monitor cable etc, with o difference.

So I wonder if I have a dodgy video card, or a motherboard that somehow thinks it is supposed to output mono instead of color. Unfortunately I haven't got another isa video card to test here.

Reply 1 of 8, by zyga64

Posted on 2022-11-11, 13:52

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Problems with 8-bit TVGA9000 based ISA video card

TLDR:

Grzyb wrote on 2020-04-17, 02:03:
TVGA9000i pin 46 (MONITOR) is connected to the VGA connector pin 12 (Monitor ID Bit 1) […]
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TVGA9000i pin 46 (MONITOR) is connected to the VGA connector pin 12 (Monitor ID Bit 1)

So, it works as designed.
WIth DDC2, pin 12 is serial I²C data, ie. sometimes 0, sometimes 1.
If you want a DDC2 monitor always detected as color, you need to disconnect that signal.

If you don't want to desolder this pin, you have to use Trident's smonitor.exe utility.

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4) i440BX /P!!!750 /256M /MX440 /SBLive!
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Reply 2 of 8, by flynth

Posted on 2022-11-11, 17:51

flynth Offline

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zyga64 wrote on 2022-11-11, 13:52:
Problems with 8-bit TVGA9000 based ISA video card […]
Show full quote

Problems with 8-bit TVGA9000 based ISA video card

TLDR:

Grzyb wrote on 2020-04-17, 02:03:
TVGA9000i pin 46 (MONITOR) is connected to the VGA connector pin 12 (Monitor ID Bit 1) […]
Show full quote
TVGA9000i pin 46 (MONITOR) is connected to the VGA connector pin 12 (Monitor ID Bit 1)

So, it works as designed.
WIth DDC2, pin 12 is serial I²C data, ie. sometimes 0, sometimes 1.
If you want a DDC2 monitor always detected as color, you need to disconnect that signal.

If you don't want to desolder this pin, you have to use Trident's smonitor.exe utility.

Cool, thank you for this. I really thought I have some hardware fault. I was going to be washing the motherboard as a next step...

Reply 3 of 8, by MarkP

Posted on 2022-11-14, 15:03

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I have a Zenith that does this if the monitor is still switched off when firing it up and then switch the monitor on.

Reply 4 of 8, by maxtherabbit

Posted on 2022-11-14, 16:14

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You don't necessarily need to desolder, you can just cut the trace - or even add a pull up/down depending which logical state the chip looks at as color.

Many of the trident 8900 cards I've worked with even have a jumper to override the monitor detect

Reply 5 of 8, by Namrok

Posted on 2022-11-14, 16:37

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Recently I addressed this in one of my own systems by just getting a Male to Female VGA Port Saver/Adapter, and snipping pin 12 off the male end. Makes for an easily reversible fix.

Win95/DOS 7.1 - P233 MMX (@2.5 x 100 FSB), Diamond Viper V330 AGP, SB16 CT2800
Win98 - K6-2+ 500, GF2 MX, SB AWE 64 CT4500, SBLive CT4780
Win98 - Pentium III 1000, GF2 GTS, SBLive CT4760
WinXP - Athlon 64 3200+, GF 7800 GS, Audigy 2 ZS

Reply 6 of 8, by konc

Posted on 2022-11-14, 16:57

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Namrok wrote on 2022-11-14, 16:37:

Recently I addressed this in one of my own systems by just getting a Male to Female VGA Port Saver/Adapter, and snipping pin 12 off the male end. Makes for an easily reversible fix.

Ingenious, I like this one!

Reply 7 of 8, by cyberluke

Posted on 2023-02-09, 22:58

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FYI: SMonitor utility has some bug, someone fixed it here: https://forum.vcfed.org/index.php?threads/tri … nochrome.79054/

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ColorMono.zip

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Reply 8 of 8, by Horun

Posted on 2023-02-09, 23:53

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MarkP wrote on 2022-11-14, 15:03:

I have a Zenith that does this if the monitor is still switched off when firing it up and then switch the monitor on.

I have one that does same, also have one that does opposite. 🤣 yeah it is a real thing 😀

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

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