zuldan wrote on 2025-06-29, 11:40:

butjer1010 wrote on 2025-06-29, 11:31:

So, another card, inserted right (what an idi0t i am), shows all the voltages, and clk, frame, reset also, only irdy is turned off, but nothing on led display. Do i need to put ram and vga?

Is this a different post card or the same one? Try a different ISA slot.

No post codes = CPU not working. Are the jumpers configured correctly on the board? Maybe they are set to use the 486 socket?

that cpu socket sure looks lonely...

Deunan wrote on 2025-07-30, 15:21:

4.1V might be good enough, the mobo will generate a bit higher voltage to offset any drop in the traces (the regulator is quite […]
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butjer1010 wrote on 2025-07-30, 12:53:

As You said, all 4 leads of this coil "beeps". Upper and right are connected to pin 2 on regulator, and lower pin is going thru this thick via to this violet cap near cpu. There is a 4.01V on positive lead of cap. This cap is connected to at least 15 pins on CPU

4.1V might be good enough, the mobo will generate a bit higher voltage to offset any drop in the traces (the regulator is quite far from the CPU) and it also helps the stability a bit - at the cost of higher CPU temperature.

You can check the connection to the PGA socket, use this page to find the right pins: http://ps-2.kev009.com/eprmhtml/eprmx/h12203.htm
I'm not 100% sure now if that is view from the top or bottom but it should be the top. All the red dots should have the either 5V or that 4.1V from regulator, depending on CPU setup jumpers. There is also pin J1, that one should always have 5V on it, even for low-voltage CPUs. This is the I/O reference voltage.

Couldn't find pinout for this BL CPU 🙁

old school gamer man wrote on 2025-07-30, 15:38:

zuldan wrote on 2025-06-29, 11:40:

butjer1010 wrote on 2025-06-29, 11:31:

So, another card, inserted right (what an idi0t i am), shows all the voltages, and clk, frame, reset also, only irdy is turned off, but nothing on led display. Do i need to put ram and vga?

Is this a different post card or the same one? Try a different ISA slot.

No post codes = CPU not working. Are the jumpers configured correctly on the board? Maybe they are set to use the 486 socket?

that cpu socket sure looks lonely...

I bought that board because of this IBM BL 386/486 CPU, not for 486 😀
I wanted to have most powerful 386 PC 😀
I have dozens of 486 PCs

butjer1010 wrote on 2025-07-30, 17:22:

Couldn't find pinout for this BL CPU 🙁

I never had one of these CPUs to play with but I have a broken mobo that I got for parts, it seems it had one of these but somebody tried to remove the heatsink of the CPU and ripped it off completly, along with some pads. That mobo has pretty much 386SX pinout, except some pins that are not defined on 386SX are used by IBM for cache control. These extra signals are however not compatible with Cyrix pinout.

That's why I wanted you to check the PGA socket. If neither CPU works then it's not just the BL3 that's the problem, and testing PGA is simply easier. Once you get the mobo working with PGA CPU it should also work with the BL3, and if not at least it might be easier to find the remaining problems.

Deunan wrote on 2025-07-30, 17:30:

butjer1010 wrote on 2025-07-30, 17:22:

Couldn't find pinout for this BL CPU 🙁

I never had one of these CPUs to play with but I have a broken mobo that I got for parts, it seems it had one of these but somebody tried to remove the heatsink of the CPU and ripped it off completly, along with some pads. That mobo has pretty much 386SX pinout, except some pins that are not defined on 386SX are used by IBM for cache control. These extra signals are however not compatible with Cyrix pinout.

That's why I wanted you to check the PGA socket. If neither CPU works then it's not just the BL3 that's the problem, and testing PGA is simply easier. Once you get the mobo working with PGA CPU it should also work with the BL3, and if not at least it might be easier to find the remaining problems.

Ok, i will try 486 socket and let You know....
Thanks

Deunan wrote on 2025-07-30, 17:30:

butjer1010 wrote on 2025-07-30, 17:22:

Couldn't find pinout for this BL CPU 🙁

I never had one of these CPUs to play with but I have a broken mobo that I got for parts, it seems it had one of these but somebody tried to remove the heatsink of the CPU and ripped it off completly, along with some pads. That mobo has pretty much 386SX pinout, except some pins that are not defined on 386SX are used by IBM for cache control. These extra signals are however not compatible with Cyrix pinout.

That's why I wanted you to check the PGA socket. If neither CPU works then it's not just the BL3 that's the problem, and testing PGA is simply easier. Once you get the mobo working with PGA CPU it should also work with the BL3, and if not at least it might be easier to find the remaining problems.

I have checked PGA socket, and it has 5.07V on all Vcc "red dots". So i need good known DX2 CPU to test this board (tried so far with 2 untested and there was no change)....

So you need a 5V 486 CPU. It's possible but unlikely that the ones you have are both completly dead. At this point it would be best if you had some sort of oscilloscope, these days even those cheap LCD kits can do most of what is required here. Otherwise there is going to be a lot of guesswork and time consuming experiments.

If you don't want to spend money but like soldering then a cheap "logic probe" might be of some use here as well. A logic chip like 74LS00 or 04, two LEDs (green and red), two resistors, some wire. And 5V supply but that can be also provided by the PC PSU that the mobo uses. I can draw a simple schematic on how to build that. But a cheap scope would be far superior to such "probe".

Guess it's time to buy osciloscope 😄

VRM pin voltages on a working Cougar board:
top to bottom
12v
2v
2.2v
gnd
4.7v
4v
12v

1.6v is off.
replace that component before tweaking other stuff

pshipkov wrote on Yesterday, 05:42:

VRM pin voltages on a working Cougar board: top to bottom 12v 2v 2.2v gnd 4.7v 4v 12v […]
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VRM pin voltages on a working Cougar board:
top to bottom
12v
2v
2.2v
gnd
4.7v
4v
12v

1.6v is off.
replace that component before tweaking other stuff

On my VRM is:
11,84V
1.63V (when i changed jumper JP1 and JP7 to 486DX2) 1.67V when on onboard CPU
2.2V
gnd
4.67V
4.03V
12.08V
So it could be VRM that causes problems?

I thought that the should be 4v pin is 1.6v for you, but it is actually the 2v one, so the 1.6v you get is kind of on the fence.
Let me measure on the other boards to see what the value is on them …

In the meantime, i tried with good known DX266 (overdrive), and same thing again. No beeps, black screen, only keyboard blinks after turn on the psu...

Ok, the voltage at that pin varies between 1.6 and 2 between the 4 different motherboards, so you are within range.

I took a moment to measure the circled by you resistor arrays.
Their values are fairly consistent.
There are 3 types as i can see:
type 1 (next to the RAM slot) - first pin is ~1 ohm all other pins 1 kohm
type 2 (next top the RAM slot, but the shorter resistor array) - first pin 175 ohms, all other pins 500 ohms
type 3 (above the IDE connector) - 10 kohm

With that said - it is highly unlikely that all these resistor arrays got damaged somehow at the same time.
Also, the fact that the +5V red rail was not connected is highly unlikely to be a problem.
In fact, some boards are partially working with only one of the AT PSU connectors plugged in.
Stating it for a reference.

pshipkov wrote on Yesterday, 19:35:

Ok, the voltage at that pin varies between 1.6 and 2 between the 4 different motherboards, so you are within range. […]
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Ok, the voltage at that pin varies between 1.6 and 2 between the 4 different motherboards, so you are within range.

I took a moment to measure the circled by you resistor arrays.
Their values are fairly consistent.
There are 3 types as i can see:
type 1 (next to the RAM slot) - first pin is ~1 ohm all other pins 1 kohm
type 2 (next top the RAM slot, but the shorter resistor array) - first pin 175 ohms, all other pins 500 ohms
type 3 (above the IDE connector) - 10 kohm

With that said - it is highly unlikely that all these resistor arrays got damaged somehow at the same time.
Also, the fact that the +5V red rail was not connected is highly unlikely to be a problem.
In fact, some boards are partially working with only one of the AT PSU connectors plugged in.
Stating it for a reference.

So the VRM is probably ok...
As for resistors, You have probably measure them wrong. Those 3 arrays are 3.3kO, 4.7kO and 10kOhm. At least that is written on them, and (on my board) mostly they shows such resistance, except what i wrote in post before :

On RP13 first (common leg) and leg 2,3,4 and 5 have resistance of 4,67KO, and first and 6,7 and 8th leg have resistance of 3,2KO.
On RP19, first and all the legs except 7th, have normal resistance of 10KO, but first and 7th leg have resistance of 3,64KO.
On RP 24 first and 2,3,and 4th leg have 3,2KO, and first and 5,6,7,and 8th leg have normal resistance of 10KO.