First post, by Predator99
...to continue this topic in the wrong thread..
Re: Bought these (retro) hardware today
You're welcome. You should start by figuring out if the oscillator is working at all e.g. see if there is a CLK signal at the ISA slots (test between pin B20 and ground http://www.hardwarebook.info/ISA#Pinout)
It was about this board:
In the mean time I have
- cleaned with a toothbrush
- (temporaly) replaced the crystal and the 8284. Now my Mutlimeter shows 4.77 MHz on the ISA bus
- added missing CAP on C7
- replaced the CPU
But still: Nothing 🙁
Therefore I assumed a bad BIOS. I build this adapter
https://www.elektronik-technik.biz/liste/%234 … rs/READ2364.gif
And read the ROM in my TL866 and the image its exactly the same as the one found in the net. Therefore the BIOS is OK.
For further diagnostic I build the opposite adapter to use the Supersoft ROM:
This is the construction you see on the photo 😎 I verified this with the other Adapter and it works.
But also with the Supersoft-ROM: Nothing. No Beep, nothing on the CGA.
Somebody has an idea where to continue? I suspect some of the logic ICs as some seem to be rusty (as U62 / U79)...but I cannot desolder one after one and check them?