In that case insert it the right way around and check if it gets really hot in a short time. If not, it might have survived (Maybe also check the other chips on the board). And try a CPU that works with the preset voltages.
1+1=10
wrote:In that case insert it the right way around and check if it gets really hot in a short time. If not, it might have survived (Maybe also check the other chips on the board). And try a CPU that works with the preset voltages.
The BIOS chip is now correctly orientated. I powered on the mobo, and tried to sense the temperature (increase) with my finger on this chip, but it was difficult to determine if there was any heat coming from it. The CPU was getting warm, but not the BIOS chip. Also, I tested the 2 SiS chips for warmth, but felt none. The AMIKey chip did not emit any heat either, neither did the cache chips.
I will now remove the DX CPU, and replace it with an AMD DX4-100 CPU. I think this requires 3V...
Nope - using the DX4-100 won't make the mobo POST. I tried both BIOS chips; the old and the new.
Damn...it's not looking good 🙁
And we don't even know for sure that the BIOS is the problem. Might aswell be some loose solder joint or some chip that's ESD-zapped to death.
Could also be a capacitor, those don't always fail with a bang or show visible bulging (even though 486 was looong before the capacitor plague).
wrote:Damn...it's not looking good 🙁
I know. I tried removing 4 of the 9 cache chips. This new cache configuration = 128K. That didn't work. I could remove the other 5 cache chips (4 chips, plus the 1 TAG chip), but there's no 0kb cache mobo jumper option.
wrote:4) CPU type = […]
4) CPU type =
-.-.
-.-.
-.-.
-....
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This doesn't look right. Compare with the settings from the manual:
wrote:This doesn't look right. Compare with the settings from the manual: […]
This doesn't look right. Compare with the settings from the manual:
You're absolutely correct. I got the jumpers wrong. To be completely honest, about 45 minutes after I posted my "dot dot dash dash" configuration thing, I realised I had made a mistake. I corrected this mistake on the mobo itself, and retested it. No joy. I decided not to edit my erroneous post through a combination of apathy and shame! 🤣
wrote:wrote:Damn...it's not looking good 🙁
I know. I tried removing 4 of the 9 cache chips. This new cache configuration = 128K. That didn't work. I could remove the other 5 cache chips (4 chips, plus the 1 TAG chip), but there's no 0kb cache mobo jumper option.
You were absolutely right about it not having any jumper settings for 0kb cache. I read some 486 manuals from th99 and some have the jumpers for 0kb and some don't.
Even if the mobo is dead, you 'could', if you're up for it, remove the remaining cache chips and put them in a known working motherboard and do some testing to see if it's broken. If not, then atleast you'll have some extra cache chips on hand (which is a good thing in itself).
Back when I was finding lots of 486 mobo's when dumpsterdiving I found many 486 mobo's had been damaged by corroding batteries and before tossing those boards I removed all the cache chips as I thought I might have a use for them later.
That, and I knew that at one time 486 mobo's would 'run out' and start getting scarce and that a few years down the road it would become much more difficult to obtain these cache chips.
I still have them, though most are I think 20ns instead of the more useful 15ns.
When I declare a mobo definately dead, I strip it of all it's potential useful components, including cache chips, jumpers and perhaps even the socket lever...yup, I actually fixed 2 'broken' motherboards that had the lever broken off and replaced those levers with ones from mobo's that had intact levers as spares.
...ok, maybe I'm going a liiittle bit overboard hehe 😜. Call me crazy 😜
