I dont know if this would make a difference, but it seems JP2 is set to Mono on your board?

Clearly CPU/RAM/cache is OK if you are able to get a beep and (blindly) access the bios setup.

(https://stason.org/TULARC/pc/motherboards/A/A … ISA-486SIQ.html)

Ooops. Yes, I had it set that way as part of the testing when I took the photo. I have tried it both ways with both cards and it doesn't seem to make a difference either way. 🙁

The Mono/Color switch is intended for monochrome and CGA cards. With EGA/VGA either of the two jumper positions should work.

What monitor are you using for testing? I have some older cards that work just fine but won't display anything on an LCD for example, even though the system is able to complete POST just fine.

Also, if you haven't it's always a good idea to try the cards in different slots, sometimes the contacts have some crud that prevents cards from working properly. If you have some contact cleaner (or just alcohol) you can try scrubbing the slots to clean any corrosion.

In any case, the motherboard appears to be working and seems to be in good physical condition. Can you take a pic of the backside in case there's any corroded traces?

EDIT: regarding the Tseng card, are you sure that one works with only 2 memory chips? Currently it has 256KB of RAM in total, which should be OK for VGA, but I wonder if filling at least 4 sockets is necessary... that should be 1 bank I believe? Unless it has 4 banks, but that's not really common in my experience.

Thanks for that info and suggestions. I do have a modern widescreen on techbench because I primarily work on much newer systems. That being said, that video card has initialized and worked fine on that monitor on other 486 boards I have around.

BUT, per your suggestion, I pulled the oldest monitor I have laying around. Its still an lcd panel as I dont have any CRT's around at all. Its and old Gateway FPD1520 from around 2001 I think. Still no video.

Here is a picture of the underside of the MB. Sorry about the glare.

As for the Tseng card.. I had not thought about the cache. I know for a fact that card has worked on one of my boards. But I do think it has not worked more often than it has and maybe thats the issue with it. I'm going to look around to see if I find any spare cache that will work in it and give it a try and get back to you. I may need to temporarily borrow some chips from the other card.

Oh. The board had a full cleaning a few weeks before I started testing it. I have tried the card in all the slots and also taken QD Electronics Cleaner to them and the card as well.

This motherboard seems to have an ISA bus fault as none of the slots are working. A corrupted BIOS image could also prevent MB to complete a POST, but it's probably not it in this case.

If fault is really in the ISA bus, then you can suspect: bad ISA bus address/data buffer chips, damaged tracks, vias, short circuit in or under the slots, or cold soldering of the chipset joints.

Try the following steps:
1. Force one of the graphics cards to run in 8 bit mode (if any support that) on a motherboard that is known good;
2. Put that video card in the faulty motherboard's 8 bit slot and see what happens.

If you get video - fault is in the 16 bit section, if there is no video - fault might be in the 8 bit section or both. Knowing this will make it easier to find the cause of the failure.

Yeah, it's quite strange. Personally I think the board is mostly fine... what happens if you try to turn it on without a video card? Do you get the AMI beep code for missing video consistently? There are indeed some boards that are quite finicky about what graphics cards they like, but usually in those cases you don't get a POST as the board behaves like there is no video card installed. Additionally, ASUS boards of this era are quite hassle-free, they really started to build their brand with these... I have the larger cousin of this one (the ISA-486, also a SiS chipset and AMI BIOS) and it works with every Tseng and WD card I've thrown at it.

By any chance do you have a programmer that can read the BIOS chip? In that case, we could compare it with the one in UltimateRetro (and maybe even try that one on your board). Still, if you get a memory count it means the BIOS is executing code and it's most likely fine... I guess there is a possibility that the BIOS is corrupt and the code that initializes the video ROM is affected, but I don't remember if the system BIOS checksum is verified before or after video init.

Also, good suggestion above about trying cards in 8-bit mode if you can!

pc_oldtimer wrote on 2022-12-15, 23:52:

Hello retro PC fans. This is my first post here so please be gentle. :-) I have a a 486 motherboard that seems to work. Except […]
Show full quote

Hello retro PC fans. This is my first post here so please be gentle. 😀
I have a a 486 motherboard that seems to work. Except I get no video. I am just getting started collecting retro hardware so I only have 2 ISA video cards to work with. Both of the video cards are known good. If I put one of those video cards into this board, the board gives no video, no beeps, and no response from the keyboard. A diag card stops at 2C (AMI). If I put the other card in there, I get no video but I do get the memory tick sound and a beep. At that point I can press F1 ( and get another beep). This is presumably the BIOS needs setup, press F1 to continue message and makes me feel the board is probably still in descent shape. But thats all I get. It doesn't matter which slot I use, the results are the same. No video. I've checked and re-checked all the jumpers (the best that I can). Does anyone have any ideas what the issue could be? Could it just be this board is super fickle about video cards?

The board appears to be an ASUS ISA-486SIQ. I have attached a picture of the actual board.

Any thoughts or ideas would be greatly appreciated.

Motherboard w/DX-33 CPU and 4MB RAM
ISA-486SIQ.JPG

Video Card that seems to prevent the system from posting
DontWork.JPG

Video Card that the system seems to boot but nothing on display
AlmostWorks.JPG

Hi, I saw your post and your motherboard, and it occurs to me that some ISA16bit video cards work if installed in ISA8bit slots, I don't know if the ones you have can work on an XT, but maybe if you try them in ISA8bit slot (the one under the BIOS chip), and you're lucky you could have a video signal, in that case as they suggested before it could be the ISA16bit part that has a fault (somewhere?) or a contact problem, or some soldering from redo.
However, understanding where the fault is, i.e. for example in the ISA16bit, you avoid trying and testing at random, of course if you can have a second BIOS chip, I think it would give you some certainty that one of the two works, and therefore the problem it should be hardware only.

These look a bit weird to me, not sure...

Dang I submitted a reply to some of the above but it disappeared.. Sigh. Ill try again 😀

@ SSTV2: I dont know how to force either card into 8-bit mode as I have been able to locate any documentation for them. But in the 30+ years I've been a tech and in IT, it never occurred to me (even back in the day) to run them that way. Or even to put a 16-bit card into an 8-bit slot. Wow..

@ TheMobRules: I wish I had a BIOS programmer. I have several other board in "the pile" and I am almost positive some of them need a new chip or to be re-programmed. So getting a programmer / reader has been on my todo list for a while. I just need to figure one to buy that will work on most of the chips from the 90's and 2000's. Any suggestions? Maybe I can put it on my Christmas list and one of the kids will buy it for me. 😁

@ EduBat: Nice catch on those solder joints. I will re-do them later tonight when I clean up the old battery holes and add posts to them.

Update:
No video card installed = I get the 8 short beeps (no video)
WDC card installed in the 16-bit slots = System seems to boot but gives no video
WDC card installed into the 8-bit slot = 8 short beeps (no video)
Tseng card installed into any slot (8 or 16 bit) = no beeps, no video, nada. Diag card stops with a last code of 2C (AMI bios)

pc_oldtimer wrote on 2022-12-16, 21:41:

Any suggestions? Maybe I can put it on my Christmas list and one of the kids will buy it for me. 😁

Definitely the TL866. It's relatively cheap, reliable and works with pretty much everything (except maybe older stuff like Commodore ROMs that need higher voltages). Also you can use it to test logic chips and SRAMs. An invaluable retro tool really.

pc_oldtimer wrote on 2022-12-15, 23:52:

Hello retro PC fans. This is my first post here so please be gentle. :-) I have a a 486 motherboard that seems to work. Except […]
Show full quote

Hello retro PC fans. This is my first post here so please be gentle. 😀
I have a a 486 motherboard that seems to work. Except I get no video. I am just getting started collecting retro hardware so I only have 2 ISA video cards to work with. Both of the video cards are known good. If I put one of those video cards into this board, the board gives no video, no beeps, and no response from the keyboard. A diag card stops at 2C (AMI). If I put the other card in there, I get no video but I do get the memory tick sound and a beep. At that point I can press F1 ( and get another beep). This is presumably the BIOS needs setup, press F1 to continue message and makes me feel the board is probably still in descent shape. But thats all I get. It doesn't matter which slot I use, the results are the same. No video. I've checked and re-checked all the jumpers (the best that I can). Does anyone have any ideas what the issue could be? Could it just be this board is super fickle about video cards?

The board appears to be an ASUS ISA-486SIQ. I have attached a picture of the actual board.

Any thoughts or ideas would be greatly appreciated.

Motherboard w/DX-33 CPU and 4MB RAM
ISA-486SIQ.JPG

Video Card that seems to prevent the system from posting
DontWork.JPG

Video Card that the system seems to boot but nothing on display
AlmostWorks.JPG

On this WD video card:
Open all jumpers near metal bracket. This will be standard VGA mode.

Cheers,

@ TheMobRules: I've added the T48 version to my Christmas list. I'm sure one of the kids will buy it for me for Christmas as they always tell me they have no idea what to by me. So maybe next week I will get to check the rom out. 😀

@ pentiumspeed: I appreciate the info. I tried removing those two jumpers. But it did not seem to have any effect.

@ EduBat: I re-checked those solder joints. They are all solid and in good shape. I think it was just the odd lighting I have at the bench.

The kids didnt buy the rom programmer for me for Christmas so alas, I ordered it myself. Hopefully it will arrive this weekend.