Are you sure? That's not generally how it works. E.g., the chip's pin (2) will usually be pulled up to +5V or down to Gnd to provide a default state just in case the jumper is missing or ineffective, and then Pin 1 will be +5 and Pin 3 will be Gnd (for example). If you set the state of pin 2 THROUGH a resistor to Gnd, then either pin 2 has to have a very weak pullup to +5v (100K? 500K?) or it's floating -- which is just bad design.

It's also possible that, for example, pin 1 is the chip's IO pin, pin 2 is tied to ground via resistor, pin 1 and 2 are connected, and pin 3 is tied to +5V. That way, if the jumper is in 1-2 position, it's not really doing anything -- just shorting the link that already exists on the PCB anyway. But, if you move the jumper to 2-3, you're over-riding the R to Gnd with +5V, and since 1-2 are connected, that sets the voltage on Pin 1 as well.

Ok i had time to poke around.

1.
JP1-6 and 8-11 have no connection on pin 1; and are connected to gnd via 10k resistors.
They only have an effect when i put them directly to gnd (1k also works).

2.
JP7 and 12-15 are IRQ jumpers (LPT/COM) and go to the chip and irq-buslanes, without resistors.

3.
Jumpers for:
- COM A/B enable/disable
- COM adress
- LPT enable/disbale
- LPT Bidirectional/Output
are going to the controller chip and further to this "HM8388P" dip20.

4. Jumper 6 "LPT Port"
pin 1 : not connected
pin3 : resistor -> gnd
pin2: controller chip -> cap (c4) -> gameport -> gnd

5. Strange gameport, what are 10pin gameports doing on PCs.

6. HMC HM8388P
I couldn't find a datasheet.
Pins:
1 : 12v
2-7: COM/LPT as descibed in 3.
8-9: NC
10: gnd

11-13: NC
14-19: COM-Ports
20: -12V

Measurements:
2-7: 5V... or when i pull them directly to ground (not going through the 10k resistors) change to 0V.
14-19: changing between -12/+12V depending on enabled/disabled COM-ports.

Some more things:
I got curious and pulled out the diodes through which the +-12V are going.
- The -12V side goes dark
- The +12V side gets from pin 2-7 5V.

So it seems the 5V for the defined state is originating at the controller chip.

Anyways what could be defective so that the jumpers have no effect. I mean it can't be a design mistake, or could it be that the wanted to put in 1k resistor and mistakenly got 10k ones?

Greetings and good night!

Come on, i'm in the magical Halls of Wisdom and no one has an idea?

Well i found some 1k smd resistors on a dead board and successfully relocated one to the controller...

Greetings!

but whyyyyyyyyy??????

Tough to say. Is pin 1 actually n/c, or is there a burnt/broken/corroded trace somewhere? What's the controller chip? (You say it's in parallel with the HM chip on that block of jumpers.) Is there maybe a problem with the on-chip pull-up, where it's providing a stronger pull-up than it's supposed to? Maybe the 10K Rs were replaced by somebody? Maybe it's just a piece of junk card. 😉

SirNickity wrote on 2020-02-21, 22:03:

Maybe it's just a piece of junk card. 😉

🤣 To be honest never saw a full red colored ISA HD card until now. I see lots of other ISA hd cards for sale for $10-20 on ebay and other sites but never a red one. Maybe that is an omen (I tag bad parts with a red sticker).

No, no, no... It can't be an omen or bad card. It has a sticker with "MEGA" on it. It must be megacool 😁