aknot wrote on 2021-10-22, 18:18:

This poor granny was in very bad condition. So be respectful 😀 a few things left to finish this project, but now I'm stuck with this turbo thing...

Hey it should suffice for a 10Mhz 286 😀
i also would use it! 😁

weedeewee wrote on 2021-10-23, 12:34:

Broken or faulty contact on one of the oscillators ? looks like you've got two, one I assume 16 MHz, divided by two would give the 8MHz cpu speed, and one 32MHz which would deliver the 16MHz.
One of the ceramics around them could also be at fault.

I don't have knowledge and equipment to test them, possible easiest way for me is to replace 32Mhz oscillators. Then check the issue.

Thanks!

Hey it should suffice for a 10Mhz 286 😀
i also would use it! 😁

Of course 8Mhz is enough 😀 but it would be incomplete project to left it with broken TURBO!

aknot wrote on 2021-10-24, 13:44:

weedeewee wrote on 2021-10-23, 12:34:

Broken or faulty contact on one of the oscillators ? looks like you've got two, one I assume 16 MHz, divided by two would give the 8MHz cpu speed, and one 32MHz which would deliver the 16MHz.
One of the ceramics around them could also be at fault.

I don't have knowledge and equipment to test them, possible easiest way for me is to replace 32Mhz oscillators. Then check the issue.

Thanks!

Wonder what would happen if you swapped the two temporarily just to see what would happen?

oh man nostalgia! i just remembered back in 1996 i discovered the oscillator crystal was the reason turbo malfunctioned! hope that helps but doubt eBayt has replacement need hobbyist supplier. crystals eventually crack from oscillating (vibrating) it goes to show nothing man made lasts forever. I miss playing with this stuff like the othert day i discovered some old 8086's would make a bunch of beeps when turned on but that was because when basic got forgotten people pulled the chips out of the bios bank 😀

zapbuzz wrote on 2021-10-24, 18:25:

... doubt eBayt has replacement need hobbyist supplier. ...

Dunno where aknot is based, but quickly checking on ebay in the UK there's a seller offering them for a bit over £5 including postage, so might get lucky. Before that though, Jakethompson1's idea of putting the 16MHz oscillator in place of the 32MHz one sounds like a good way to check if that's the source of the problem.

snufkin wrote on 2021-10-24, 19:40:

zapbuzz wrote on 2021-10-24, 18:25:

... doubt eBayt has replacement need hobbyist supplier. ...

Dunno where aknot is based, but quickly checking on ebay in the UK there's a seller offering them for a bit over £5 including postage, so might get lucky. Before that though, Jakethompson1's idea of putting the 16MHz oscillator in place of the 32MHz one sounds like a good way to check if that's the source of the problem.

Thanks guys for suggestion. I ordered a few oscillators and will let you know the status as soon as I will replace them. I'm EU located 😀

Hi all,

Well it took a some time to get oscillator and change it, but... oscillator wasn't the issue. After soldering work, there was the same behavior. So, forced to find I guy with measurement tools to check existence of 16Mhz on the motherboard. We found out that there is no problem with oscillator as we found these 16Mhz.
In short, two RAM chips was faulty. They was working fine on 8Mhz and passed the RAM tests, but issue came out only when CPU was working in 16Mhz.
Attached tests with faulty RAMs and when they was swapped to another + sysinfo and CPU performance 😀
So, now it works fine and the restoration project is almost finished 😀

Thanks!