Remove dead battery, look for signs of corrosion/leaking. If none connect a good battery.

Yep, I snipped the battery and did not see any leakage. You think it's needed for the card to power on?

A missing/dead battery can cause all sorts of issues. It's kind of a long shot if it doesn't even power on, but that's the first thing I would try.

OK, I'll get a new battery.

Found a PDF on my ISA backplane: http://support.elmark.com.pl/advantech/downlo … B2Eusernote.pdf

I have connected power to the screw terminal posts (TB1), but now I'm wondering if that is wrong?

Terminal block connector export +/-5V, +/-12V

What does export mean?

To me it looked like it was wired to the AT connector, but maybe I'm supposed to use the AT connector instead.

I also found a PDF for a newer SBC by the same manufacturer, I-BUS. My board is not exactly the same layout but hopefully it will get me some hint as to were the PC speaker header is.

http://www.ibus.com/manuals/manual-orca.pdf

Is VCC identical with 5V?

I will have to check that.

I made some progress now, I measured directly on the ISA bus and saw that pin B3 (5V) was only about 4V. I had used 5V from a molex connector which was apparently a bad idea. I fixed that, and connected a PC speaker. I can hear sort of a faint click when I power it on, still no picture though.

What's worse is that I discovered that the OPTi 82C493B (chipset?) IC gets VERY hot immidiately on power-on. Maybe that IC is fried? 😢

The Cyrix CPU gets kind of lukewarm.

h-a-l-9000 wrote:

Is VCC identical with 5V?

Yep, I believe that VCC is labeled +5V on my backplane.

if it gets super hot immediately, its probably got a short somewhere

I've hat the 'chip get hot' when the external CMOS battery was missing on some 386SX boards. In this case the chips were going into latch-up. Fortunately it was fixed by adding the battery.

Alright, I hacked together a battery pack (three AA batteries), output was about 4V.

Still does not show any image, chip gets super hot. Hard to know where to start hunting for shorts.

One thing that I haven't tried yet is powering on without any RAM.

Chances are it's the chip itself. Do the 4 driver chips next to the RAM also get hot? Anything else getting hot?

Do you have an ISA POST card? If there are any POST codes being broadcast then it would mean there's some life, it's just not managing to put anything on the screen. But the hot Opti chip doesn't sound good.

connected a PC speaker. I can hear sort of a faint click when I power it on

Is this happening at the instant you apply power, or is it happening some seconds later? If it's happening later then it might be a programmed beep, which means some code execution is taking place which would be encouraging. If it's happening at the moment you apply power it might just be electrical noise though.

Is there a datasheet out there for the Opti 493B chip? If so, you could try to find which pins provide the supply voltage and what that voltage is supposed to be. Odds are those ceramic caps next to the chip are in parallel with that supply, and could be used to measure that voltage while it's running. If you need to probe in a tight space, wrap tape around the probes.

I notice in the picture there are a couple of SIP components (one black, one red) plugged into a socket near the Opti chip. Have you been able to verify if those are installed correctly, or at least the same as the eBay listing you saw?

@h-a-l-9000: The IC's near the RAM don't get hot, only the OPTi.

shamino wrote:

Do you have an ISA POST card? If there are any POST codes being broadcast then it would mean there's some life, it's just not managing to put anything on the screen. But the hot Opti chip doesn't sound good.

I was not aware of these POST cards, they look quite useful and really cheap too. I'll order one.

Is this happening at the instant you apply power, or is it happening some seconds later? If it's happening later then it might be a programmed beep, which means some code execution is taking place which would be encouraging. If it's happening at the moment you apply power it might just be electrical noise though.

At the time of power-on, so sadly I don't think it's from BIOS. The thing is I don't even know if I have connected it to the right header, just guessed on which would be the most likely.

Is there a datasheet out there for the Opti 493B chip? If so, you could try to find which pins provide the supply voltage and what that voltage is supposed to be. Odds are those ceramic caps next to the chip are in parallel with that supply, and could be used to measure that voltage while it's running. If you need to probe in a tight space, wrap tape around the probes.

Good idea, there are tantalum caps nearby on the back of the card too.

I notice in the picture there are a couple of SIP components (one black, one red) plugged into a socket near the Opti chip. Have you been able to verify if those are installed correctly, or at least the same as the eBay listing you saw?

I think this is a resistor pack, terminating the IDE bus or something? I honestly have no idea. They are not in the same place as the ebay listing.

The board is 5V only. If tantalum caps were shorted you would get the *bang*, smoke or no power symptoms.
The socket above the OPTI chip appears to be for a cache module (checking the pin assignment in the datasheet). Try to remove the SIL resistors.

Also, did you try to remove the SIMMS yet?