Nope. No issues - 16MHz is the maximum rated speed; it will run happily at speeds below that rating.

therevisiona wrote on 2021-04-11, 18:11:

Horun wrote on 2021-04-10, 01:00:

This board but is near exact to my Protek 286 board but slightly different layout. Same chipset, same support chips, same DIP and SIPP memory layout.

What CPU clock does your motherboard use? My board has some markings on the back (P-286-16, not recognized by the internet), from which I assume the board used to have a 286-16 processor, but there is a 286-10 processor installed. Can this make the motherboard not boot up? Either way I'm not installing my known good 286 in fear of it being destroyed.

Mine is a 12Mhz cpu. The crystal is a 48.0Mhz just like yours. A 10Mhz 286 can usually run at 12Mhz except some of the variants run very hot (compared to Harris) so may not run well at 12Mhz.
Yes you can run a 16Mhz 286 at 8, 10, 12 or 16mhz.....

It's an original Intel CPU do maybe it is not rated for 10 MHz

I got the original monitor and it freaking worked all along. But now I'm getting something interesting. Everytime I need two tried to turn it on. I need to turn it on, turn it off, and then when i turn it on it will start up. Anybody know what could be causing it?

Bad capacitors?

evasive wrote on 2021-04-12, 14:28:

Bad capacitors?

Do tantalum capacitors go bad? They're not shorted or anything but i will replace them

Oh yeah tants go bad and fail shorted and then explode when you power on the systems. If the parts are out of a case you get quite the fireworks display.

yeah, that's the way you know a tantalum has gone bad, it has exploded 😁

therevisiona wrote on 2021-04-12, 15:06:

evasive wrote on 2021-04-12, 14:28:

Bad capacitors?

Do tantalum capacitors go bad? They're not shorted or anything but i will replace them

Well my PSU was shutting off when I first powered it up, so I cut out 3 tantalums and now it works like this. Could there be more dying that don't show symptoms of a failing tantalum?

I'd personally replace all the tantalum caps cause if 3 of them are shorted and popped the the rest aren't far behind.

Tantalum capacitors, especially those produced decades ago, are the more likely to fail the nearer they are operated at their maximum voltage.
Most manufacturers used the same voltage (25V) for 5V and 12V rails. Those in the +12V and -12V rails fail often and should be replaced completely if some have already failed.
In most cases I left those in the 5V rails unreplaced and can´t remember any problems in the years to come.

These ones are 16V, so it may be even closer to dying when run at 12V

I actually was talking about the PSU, did you check its condition as well?

evasive wrote on 2021-04-13, 08:21:

I actually was talking about the PSU, did you check its condition as well?

Yes, the PSU is fully recapped

jesolo wrote on 2021-04-09, 18:57:

You can try to dump the BIOS with Navrátil System Information (NSSI), but I can't remember how complete the image file will be, if your motherboard has an odd and even BIOS. It will most likely create one combined image which will then need to be split up again.

There is WinHex for that, when we put this board in UH19 I'll make sure it is split properly bytewise.

I think there's freeware/scripts out there too for achieving this. As long as we have all the bytes from the chips we can reorder them.

From my measurements I found out the processor is being held in reset when in the weird state, which means probably an unstable voltage, which goes back to the capacitors. I have been reluctant to desolder these capacitors in fear of damaging this multilayer board.

Also the people over at the UH19 Discord server identified my motherboard - http://www.win3x.org/uh19/motherboard/show/5234.

No idea if you have a battery connected or not, but definitely add a battery, some boards just won't boot without it.

therevisiona wrote on 2021-04-14, 06:44:

From my measurements I found out the processor is being held in reset when in the weird state, which means probably an unstable voltage, which goes back to the capacitors. I have been reluctant to desolder these capacitors in fear of damaging this multilayer board.

A pretty common problem is battery spill eats the power good signal from PSU - that will keep the CPU in reset. On these mobos there can be a gate or two between this signal and chipset, so trace that, it might be a break between the gates or the last gate and mobo chipset - that chip is usually close to battery and RTC. The (usually CMOS NOT or NAND) device itself could've failed too but it's rare. Gated power good is also often used to lock out chip enable on the RTC/NVRAM chip, but that shouldn't keep the CPU in reset (but might prevent boot with a black screen - but you will get some early codes on a POST card at least).

Note that power good is just a simple logic signal, usually just a delay, and doesn't not indicate if the +5V is actually any good. But unstable rail will not cause a permanent reset unless it's really low (like 3V or less).

EDIT: Also, using NSSI (or any other software) to dump BIOS can result in bad image if the mobo supports RAM shadowing. Preferably disable that before dumping and always verify the checksum of the file. It is usually possible to fix the image, there's just a small range that needs to be zeroed out, but that depends on the particular mobo and BIOS.

It now boots properly, I put a 6V CMOS battery on the external headers and it finally works so I will send the bios here and on the UH19 Discord server