VOGONS


Reply 80 of 137, by snufkin

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PC@LIVE wrote on 2021-12-04, 13:31:
Yes ok thank you very much, I knew what the two displays indicated, but I don't understand if they indicate something that does […]
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weedeewee wrote on 2021-12-04, 13:21:

FYI, the codes you see, the first two digits are one code, the second two digits are the previous code.
that's how that post card shows the port 80 post codes. current / previous.

Do you get the same codes on the post card when inserted into the pci slot ?

Yes ok thank you very much, I knew what the two displays indicated, but I don't understand if they indicate something that does not work on the MB, because in the booklet in many of those codes there is nothing written.
Honestly I have not tried on the PCI slot, for convenience I use the ISA one, because it is better visible, the PCI one the card goes to the opposite side, and you have to go and see if it shows something.
Among other things, I noticed that a couple of LEDs change on the PCI (on and off), I hope it is normal, the + 3.3V for example turns off.

In any case I try to make some attempts with the POST CARD in the PCI, I'll see if it goes the same, but I don't think it changes much.

I can be dense at times. I don't think ISA slots have 3.3V to them, so that 3.3V LED must be showing something else when it's plugged in to the ISA slot (-5V maybe?). So to check 3.3V the card would have to be in a PCI slot.

Reply 81 of 137, by PC@LIVE

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snufkin wrote on 2021-12-04, 14:11:
PC@LIVE wrote on 2021-12-04, 13:31:
Yes ok thank you very much, I knew what the two displays indicated, but I don't understand if they indicate something that does […]
Show full quote
weedeewee wrote on 2021-12-04, 13:21:

FYI, the codes you see, the first two digits are one code, the second two digits are the previous code.
that's how that post card shows the port 80 post codes. current / previous.

Do you get the same codes on the post card when inserted into the pci slot ?

Yes ok thank you very much, I knew what the two displays indicated, but I don't understand if they indicate something that does not work on the MB, because in the booklet in many of those codes there is nothing written.
Honestly I have not tried on the PCI slot, for convenience I use the ISA one, because it is better visible, the PCI one the card goes to the opposite side, and you have to go and see if it shows something.
Among other things, I noticed that a couple of LEDs change on the PCI (on and off), I hope it is normal, the + 3.3V for example turns off.

In any case I try to make some attempts with the POST CARD in the PCI, I'll see if it goes the same, but I don't think it changes much.

I can be dense at times. I don't think ISA slots have 3.3V to them, so that 3.3V LED must be showing something else when it's plugged in to the ISA slot (-5V maybe?). So to check 3.3V the card would have to be in a PCI slot.

Ok thanks a lot for the suggestion, I don't know why that LED is off on the PCI, maybe that's the problem?
But some MB work the same without the + 3.3V LED turned on, it is a question of whether there is actually that voltage, or not? Then it is strange that in the ISA one it is on, surely, what does it mean I do not know the -5V led is missing (there is the -12V one), you must probably check if the 3.3V actually arrives at the PCI, it could be that that PIN used by the Post card has no voltage, and others do?
Maybe it would be better to check if you also get to the ram and AGP, maybe the AGP is fine because with the VGA inserted it shows more signs of life than the VGA PCI or ISA.

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AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 82 of 137, by weedeewee

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3v3 is allowed to be missing on those PCI slots.
It shouldn't be a cause of no boot.

Right to repair is fundamental. You own it, you're allowed to fix it.
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Reply 83 of 137, by PC@LIVE

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weedeewee wrote on 2021-12-04, 16:24:

3v3 is allowed to be missing on those PCI slots.
It shouldn't be a cause of no boot.

Ok thanks for the info, but I think it could be a RAM or CPU problem, maybe I try to clean the pins of the slots, it could be a contact problem, then if nothing changes I'll try to see if there is any voltage in the slots or in the ram without voltage (+ 3.3V), because maybe in the PCI it is not necessary but in the RAM I think it is essential.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 84 of 137, by PC@LIVE

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Since with two BX I can't solve, so to speak Lucky Star 6ABX2V and ASUS P2B-F, I dust off another one, a SOYO SY-6BA + IV, always Slot1 and BX chipset, even if it is an improved version having a faster HD controller with Highpoint HPT366 chip and with RAID.
I try to start with a Celeron Mendocino 370 and Slot1 adapter, PC133 RAM and the usual VGA AGP with ATi 3D Rage Pro Turbo chip, unfortunately after several attempts nothing happens, always - - in the POST CARD display, I check the voltages all ok.
At some point after various RAMs I try to change the CPU, I put the Pentium II 300 that was on the ASUS, I try again but still nothing, then I change the RAM, I put a PC100 32MB with 16 GM72Vxxxxx chips (double sided), here are the codes in succession and starts!
Obviously the BIOS messages due to low battery (changed before booting) appear, I press DELETE to enter the BIOS, and I enter to have a look if I notice abnormal values, there is something strange but nothing important, the frequency is indicated in 200MHz, but actually in the start screen you see the right frequency 300MHz, obviously this CPU has FSB 66, if I set 100 and it started it would go to 450MHz, this thing was easy to do in Celeron Mendocino, with a I even got there to 112 of FSB, but in this Mb I am not interested in overclocking, otherwise everything is ok by pressing F1, it continues until the operating system message is missing.
This is because I haven't connected a hard drive or IDE-CF adapter and memory card yet, however I assume everything is working normally.
The MB was repaired some time ago by replacing two electrolytic capacitors with recovery capacitors of the same capacity and voltage, those used are 1000uF 6.3V OSTs (normally having new ones I would have used Rubycon or other branded capacitors), unfortunately the original ones were swollen and with high ESR, one 13.8ohm and the other 23.1ohm and then they were at a loss (undetectable capacity).

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AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 85 of 137, by PC@LIVE

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I continue with the work among the other MBs to be repaired, I have different types, for a while I preferred the 386 and 486 ones, after a P4 60, now I'm working on various MBs for Slot1 or 370 CPU, in addition to the LS 6ABX2V and the ASUS P2B-F, I fixed the Siemens D1107 and the Soyo SY-6BA + IV.
But I also have two other Siemens, a D1120 with Celeron 566, it does not want to start anymore, the card went on years ago then one day it did not start anymore, that is, the fans start and sometimes you see one or two post codes, and nothing else.
The other instead is a D1115, slot1 with PII 400, this does not start, that is, it does not start at all, the post card LEDs are off and the fans do not turn (power supply included), here I don't know if it doesn't start for some problem or there's more.
Both of these cards are in excellent condition, they look almost new, but despite several attempts they do not start.
The reason why those cards do not start with the post card stopped on - -, should be either the RAM or the CPU (or both), the voltages have been measured on the various mosfets (or other), and I can't find anything strange, on Siemens unfortunately the BIOS chip is soldered so it is not possible to reprogram it (not even hot), I don't know why they don't work, I was thinking about the electrolytic capacitors, here they seem to be in excellent condition but we should test them to see if anyone is faulty.
Tomorrow I go back to the LS 6ABX2V, I start looking for voltages on the RAM slots, maybe there may be some voltage absent.

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AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 86 of 137, by PC@LIVE

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As I had anticipated, I took the LS 6ABX2V again, but before that I dealt with the ASUS P2B-F again, in this I checked if there is voltage in the ram, and what I found there are 3.47V on pins 6 and 41. I did not check other PINs because I think they are connected to each other, so it should be automatic to find the same voltage in other PINs.
I remember that this MB (P2B-F), with the Post Card in the PCI has the + 3.3V led off, if instead it is in the ISA the + 3.3V led is on, in practice it should be on the contrary on in the PCI and off in the ISA.
In this regard I investigate and detect the voltages in the PCI and ISA slots, the values ​​detected are perhaps only indicative, but compared with another MB that I had tried to repair in the past (PINE SI21 SiS chipset), they detect strange voltages, and probably the Post Card interprets voltages below 5V as 3.3V, otherwise I cannot explain why the LED in the ISA slot is on.
The values ​​that I find anomalous (in my opinion) were found in the ISA Slot at the PINs of the ISA 8 bit slot, the upper contacts are those indicated with A, the lower ones are indicated with B. So A4 A5 A6 A7 A8 A9 are all a + 0.88V A10 is 1.00V, others look weird and they are the ones that came from A24 to A31 but for these I don't know what they are, so they might be normal. On the B side I find strange B11 + 3.48V and B12 + 3.45V, B13 and B14 both at + 1.27V, B15 at 1.21V, B17 at 1.22V, B21 B23 B24 B25 all at + 0.95V, B26 at + 1.22V and B28 at + 3.38V. Still in the ISA slot but in the 16bit part, I find strange many PINs both on the A and B side, for the sake of brevity I say that the greatest voltage is + 3.43V and others have a voltage of about + 0.88V. Here in my opinion there should be the problem that causes the start not to start, many of the PINs that mark + 3.43V should be around 5.0V, then I don't know maybe it works the same with the 5V voltages a little below 3.5V.
In the PCI slot, check the voltages, I find a couple of weird values, maybe there are three, so it is possible that it is okay or only those are missing.

Going back to the LS 6ABX2V, I found almost the entire ISA slot with the voltage below 1.00V, but it seems that the ground pins (black wire) also mark a positive low voltage instead, this could explain why holding the PWR button The boot does not turn off, usually connects the positive to ground, but finding positive voltage does not turn off.
I also notice that the SB heats up a little more than normal, touching it is hot, it does not burn but the others are cold in comparison, I hope it is not a symptom of a partial short to that chip, the part that starts the MB works, the rest I don't know since it won't start.
I remember replacing a small EC13 capacitor burst below, it is located between the two ISA slots, I don't know what it is connected to, but the burst could be due to an excessive voltage that came due to a fault ???
I could not check the PCI slot, because I would have to take the measurements from below the MB, and it is not very simple, you risk touching the neighboring PINs, however I imagine to find strange values ​​even here as soon as I can check the voltages.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 87 of 137, by PC@LIVE

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I go back for a moment on the problems found in some motherboards, lack of voltages or low values ​​in the ISA or PCI slots, other symptoms are more serious with positive voltages in the grounded PINs.
Just the last problem, it could be the cause of the failed start, I have a couple of PCI sound cards among the cards under repair, maybe there are three but I can't find where the third one is, however the sound cards are from the Creative Labs model: CT4810 , the problem is that when I insert one into a working PC it does not start, it is possible that there is a failure somewhere, but from a previous experience with another card and the same symptoms, I know that contact between two is enough PIN to prevent starting, here I don't know if there is short circuit or overvoltage protection in the MB, in the LS 6ABX2V it seems to me that the AIC 1569CS chip does that job, and I think there is something like this in all MB of the period. I exclude the power supply because the CPU fans spin, so if it were there the protection would not spin or would make an instant movement and then stop, this happens when a line is shorted.
Here it would be interesting to know if some pins are important for correct functioning, and which are the ISA and PCI slots, then knowing which they are we should understand why we measure wrong voltages, I think that many apparently faulty boards do not have unsolvable failures, often just replace even one component to make the motherboard boot normally again.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 88 of 137, by PC@LIVE

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snufkin wrote on 2021-12-04, 14:11:
PC@LIVE wrote on 2021-12-04, 13:31:
Yes ok thank you very much, I knew what the two displays indicated, but I don't understand if they indicate something that does […]
Show full quote
weedeewee wrote on 2021-12-04, 13:21:

FYI, the codes you see, the first two digits are one code, the second two digits are the previous code.
that's how that post card shows the port 80 post codes. current / previous.

Do you get the same codes on the post card when inserted into the pci slot ?

Yes ok thank you very much, I knew what the two displays indicated, but I don't understand if they indicate something that does not work on the MB, because in the booklet in many of those codes there is nothing written.
Honestly I have not tried on the PCI slot, for convenience I use the ISA one, because it is better visible, the PCI one the card goes to the opposite side, and you have to go and see if it shows something.
Among other things, I noticed that a couple of LEDs change on the PCI (on and off), I hope it is normal, the + 3.3V for example turns off.

In any case I try to make some attempts with the POST CARD in the PCI, I'll see if it goes the same, but I don't think it changes much.

I can be dense at times. I don't think ISA slots have 3.3V to them, so that 3.3V LED must be showing something else when it's plugged in to the ISA slot (-5V maybe?). So to check 3.3V the card would have to be in a PCI slot.

I'll come back to the topic if you want to take a look at what was written above.
To summarize briefly: In the LS 6ABX2V I found the ISA slot totally messy, the voltages are very low around 1V or less, and many pins should be ground, instead they have a higher voltage than what I usually detect in those pins (0.02V) .
I also note that the SB chip heats up, the others are cold (including mosfet), maybe the problem is somewhere in the SB, if the ISA slot is connected directly to the SB without going through other components, I would say that at this point it seems to me partially failure, because the starting circuit works but the shutdown does not work.
Regarding the ASUS P2B-F instead in this there are several pins in the ISA slot with a voltage of about 3.45V, and this I think causes the LED to turn on + 3.3V, the PCI slot seems quite ok, perhaps it would be necessary to check it AGP slot but first I think the ISA needs to be fixed, as long as those +3.45 voltages are a cause of malfunction or even if the voltage is a lot lower than 5V can it be okay?

Siemens D1115: I learned during my research that the start circuit is always powered by the + 5VSB, and therefore a mosfet (or whatever it is) should always be powered, even if the MB is off, I will try to find what is connected to the + 5VSB and after I will see if there is voltage, if it is missing you have to find where the problem is, but finding something faulty it should be quite possible to repair the motherboard.

Attachments

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 89 of 137, by PC@LIVE

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Today I looked on the Siemens D1115 for the causes of the failed start, I checked the pins of the PS-ON and I did not detect anything strange (or maybe yes?), The pin of the + shows about 3.3V, maybe it is low as voltage, but could it still boot the MB?
By checking the PINs of the WOL I find the same voltage as the + 5VSB, the central PIN is the ground one, I don't know if by connecting the positive PIN to the ground one, the MB starts up or shortens?
I check a Qx near the PS-ON, on it it says 1B p and rotated by 90 ° it says 94, I set the analog tester on OHm x1, I put the Black test lead first on PIN 1 and check the values ​​on 2 and 3 getting no reading (the needle does not move), I go to PIN 2 and check 1 and 3 again no reading, I arrive at PIN 3 and on 1 no reading, while on 2 I get a reading of about 150OHm, this does not it seems correct to me, it makes me think that it is broken, but being the readings made on-board they could be influenced by the presence of something else, I forgot that on PIN 2 I found the same voltage as the PS-ON, this makes me think that they are directly connected , checking I don't find a direct connection, so it probably goes somewhere else.
I put an image if it can help to understand if he may have to cause the MB to fail to start, some argue that by grounding the green wire of the power supply it could start but I do not think it works if the MB does not give the ok.

Attachments

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 90 of 137, by PC@LIVE

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PC@LIVE wrote on 2021-12-08, 15:01:
Today I looked on the Siemens D1115 for the causes of the failed start, I checked the pins of the PS-ON and I did not detect any […]
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Today I looked on the Siemens D1115 for the causes of the failed start, I checked the pins of the PS-ON and I did not detect anything strange (or maybe yes?), The pin of the + shows about 3.3V, maybe it is low as voltage, but could it still boot the MB?
By checking the PINs of the WOL I find the same voltage as the + 5VSB, the central PIN is the ground one, I don't know if by connecting the positive PIN to the ground one, the MB starts up or shortens?
I check a Qx near the PS-ON, on it it says 1B p and rotated by 90 ° it says 94, I set the analog tester on OHm x1, I put the Black test lead first on PIN 1 and check the values ​​on 2 and 3 getting no reading (the needle does not move), I go to PIN 2 and check 1 and 3 again no reading, I arrive at PIN 3 and on 1 no reading, while on 2 I get a reading of about 150OHm, this does not it seems correct to me, it makes me think that it is broken, but being the readings made on-board they could be influenced by the presence of something else, I forgot that on PIN 2 I found the same voltage as the PS-ON, this makes me think that they are directly connected , checking I don't find a direct connection, so it probably goes somewhere else.
I put an image if it can help to understand if he may have to cause the MB to fail to start, some argue that by grounding the green wire of the power supply it could start but I do not think it works if the MB does not give the ok.

I wanted to correct what was written before, on the Qx signed 1Bp, by checking what it was it emerged that I incorrectly numbered the PINs, what I wrongly indicated with 2 is actually 3, and therefore the one indicated as 3 is actually 2.
So the reading of about 150OHm is between 2 and 3, if I understand correctly the PIN1 is BASE, the PIN2 is EMITTER, and the PIN3 is COLLECTOR.
So if it is correct it should be an NPN, and from the readings made it shows a broken PIN, as I would usually have to find a second reading between two other PINs.
I will see if it is possible to follow the PINs, to see if at some point they arrive at something connected to the PS-ON.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 91 of 137, by snufkin

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Unfortunately I don't really know enough about the ISA bus to know what would be expected voltages. I'm sure there will be descriptions of how it works around somewhere, and you can always compare with a working board. Mind that trying to measure the voltage of a signal that is switching (maybe like the address lines on a bus) then the meter will show something like an average voltage between the high and low signal levels. That said, you've measured quite a lot of pins and I would have guessed that some of them would be steady and read either +5 or Gnd. There's a pinout of the port here: https://old.pinouts.ru/Slots/ISA_pinout.shtml

For IDing SMDs then something like this: http://www.marsport.org.uk/smd/mainframe.htm is useful. You can look up the codes and find out that a 1Bp is BC846B, which if you look up the datasheet it's a NPN transistor. NPN transistors have a diode from base to emitter, so you can use the diode test mode to check that. Although that only tells you if the B-E is ok. Also, make sure you're not trying to take resistance measurements with any power connected to the board, otherwise you can get some wrong readings.

Other than that, unless there's anything visibly wrong, then just carry on tracing out what connects to what, look up what the parts are, draw out the connections, figure out what readings you should see, take measurements, and look for anything that doesn't match what you expect. It's mostly fairly tedious, with occasional moments of satisfaction when you finally find the one small thing that was stopping things from working. And occasional moments of annoyance when it turns out to be a part that can't be sensibly replaced.

Reply 92 of 137, by PC@LIVE

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snufkin wrote on 2021-12-09, 00:24:

Unfortunately I don't really know enough about the ISA bus to know what would be expected voltages. I'm sure there will be descriptions of how it works around somewhere, and you can always compare with a working board. Mind that trying to measure the voltage of a signal that is switching (maybe like the address lines on a bus) then the meter will show something like an average voltage between the high and low signal levels. That said, you've measured quite a lot of pins and I would have guessed that some of them would be steady and read either +5 or Gnd. There's a pinout of the port here: https://old.pinouts.ru/Slots/ISA_pinout.shtml

For IDing SMDs then something like this: http://www.marsport.org.uk/smd/mainframe.htm is useful. You can look up the codes and find out that a 1Bp is BC846B, which if you look up the datasheet it's a NPN transistor. NPN transistors have a diode from base to emitter, so you can use the diode test mode to check that. Although that only tells you if the B-E is ok. Also, make sure you're not trying to take resistance measurements with any power connected to the board, otherwise you can get some wrong readings.

Other than that, unless there's anything visibly wrong, then just carry on tracing out what connects to what, look up what the parts are, draw out the connections, figure out what readings you should see, take measurements, and look for anything that doesn't match what you expect. It's mostly fairly tedious, with occasional moments of satisfaction when you finally find the one small thing that was stopping things from working. And occasional moments of annoyance when it turns out to be a part that can't be sensibly replaced.

Thank you my friend, your suggestions are very precious, you are always very useful to me, thanks to you I understood where I was wrong and I have perfected the troubleshooting, slowly I am having the necessary experience to know what is good and what is wrong.
Regarding the MBs that I currently have on the bench, there is still the LS 6ABX2V, in this one I checked all the ISA PINs, apart from a few PINs with the correct voltages, the others have strange low voltage values, this one I have I understood by making a comparison between other MBs (including a PINE SI21 that I had tried to fix some time ago, and your suggestions were also very useful there).
Unfortunately, measuring all the PINs I have the positive and negative values ​​(e.g. +12 and -12), but I do not have values ​​compatible with the mass PINs (perhaps only a couple), and therefore this I think is due to some fault (not identified ), but since there are many PINs messed up, I think there may be a part of the SB ko, on however I could be wrong, I have to do some checks, and try to trace some PINs to see where they go, if they go straight to the SB I think it is automatic that it can be that's the problem.
Regarding the Siemens D1115, and the SMD transistor, thanks for the info, I just double checked, and strangely now I have other readings, I think there could be some oxide that skewed the previous readings, however from other investigations
executed it is normal to have + 3.3V on the PS-ON positive, and from what I understand (well?) there should also be on the PCI PIN A14, but I can't find them in the MB, I don't know if there are other ways to start a MB beyond the PS-ON, I will look in other MBs if there is voltage before starting in the PCI PIN A14, if there is this it would probably be why it does not start, hoping that it will then be easy to get to a faulty component.
I will try to retest the PINE SI21 in the next few days, with the experience accumulated with these MBs, I could perhaps identify some PINs without the necessary voltages, and with the necessary luck maybe find the faulty one.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 93 of 137, by PC@LIVE

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In the last few days I have had little time to devote to resolving motherboard failures, but thanks to the suggestions I had on the ISA I identified the voltage PINs (which they are), double-checking the annotated values ​​of a couple of MB, I notice that the voltages there are, and therefore the problem is only in the other PINs, some PINs may be unused, therefore not important for the operation of the card and the MB.
Understanding how they are connected still has not been possible for me, looking quickly at a 386SX I see that many PINs go quite directly to the chipset, this can make us think that in a P2 generation PC they go to the SB, and therefore the LS 6ABX2V would have a problem in the SB (since it heats up), for the moment it is not possible to replace it, I do not have a spare chip or suitable equipment, and in the absence of ideas, for a while I find myself forced to put it back in the box with the faulty cards.
I tried to fix an S370, this time it's an ASUS MEZ-M ZX chipset, you can mount Celeron CPUs, but the card has various settings for CPUs with FSB up to 150MHz.
This ASUS obviously does not work, looking for why the post card always signs - -, it is evident that the voltages on the twin mosfets are missing, they are identified as Q1 and Q3 and are both of the 32N03-L, the PIN is the G, the PIN2 is D, PIN3 is S.
The Q1 PIN2 is connected to the Q3 PIN3, the Q1 PIN3 goes to ground, the Q3 PIN2 goes to + 5V.
Unfortunately I have no voltage on PIN1 of Q1, and on PIN2 I only have + 0.30V, equal voltage on both PIN1 and PIN3 of Q3.
Looking for where the Q1's PIN1 goes (or where it comes from), there is no clear view, the presence of capacitors and more does not help, it seems to go under a HIP6019BCB chip, it should be a PWM chip with 28PIN, and it seems to be connected at + 12V (PIN VCC), unfortunately I don't know what voltages to look for in that chip, knowing which ones I could see if they are missing.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 94 of 137, by PC@LIVE

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Today I think I have made an important progress, for the resolution of the PINE SI21 failure, I had talked about it in another post (here : Identify motherboard Slot 1 SIS chipset ), the problem was basically somewhere, the post card stopped at post 41 0d with beep all 'infinite (as if the RAM was missing), but before the post 0d 0c it also made a long beep and two short beeps (video card problem), in short it was evident that there was something that was not in place, so it was thought that having the LED of the + 3.3V turned off that voltage was missing, and seeing that that voltage serves both RAM and the PCI and AGP, it was thought that this could be the problem to be solved.
In the search for the lost + 3.3V, they checked various mosfets and transistors in the MB, inductors and other things that caused an outage, but in the end after several checks everything seemed to be working, and so it was likely that the absence of that voltage was probably due to chipset failure (probably sud bridge), fortunately I do not have suitable equipment to remove and replace it (but I can tell this now), so I suspended the search for the fault and put the card away waiting for a different method to find the breakdown (which I did not know about).
Lately I have gained more knowledge of how the start circuit works, some things may be important, for example the battery always powers the MB (whether it is off or on), and the A14 PIN of the PCI is powered (usually ) when the PC is off but the power cable is plugged in (STBY), here instead there is no voltage in the PIN A14 of the PCI, I always read 0V instead of the 3.3V that are usually found, I see this in other MBs, so at this point it seems that there is nothing else to do, and just to see if I can solve at least the long beep and the two short beeps I try the video cards.
I reinserted the CPU and RAM, a PII 400 and a 64MB single sided PC100 with 8 GM72Vxxx chips, I start with an 8MB Intel 740 AGP (of a PIII 500 chipset i820), nothing changes, I switch to a Matrox Mystyque PCI I think 4MB, on this one there is an EZ1085CM used in many MB, even this test does not produce any effect, by now I had almost given up, but I have on the bench an old Western digital ISA video card with WD90C00 chip, the RAM on board it's maybe 64KB! (there are eight chips of the OKI M41464-10), it is possible to double it by finding another eight identical chips, however I start and the post card marks - -, I immediately turn off to see if something is hot enough, but nothing so I try again and after a some wait starts to display the usual post codes, until you get to the usual infinite beep!
But there is a very important news, the video displays something, it looks like the BIOS boot screen, in fact it is, but what it communicates is very important:
BIOS ROM checksum error
keyboard error or no keyboard present
Detecting floppy drive A media...
Drive A error. System halt
The message of the keyboard is correct because it is not connected, also that of the floppy is correct because I have not connected any drive, for the ROM checksum error I think it is due to the low battery, however if it looks for the floppy it is possible that it wants to do the BIOS recovery .
In this regard I have various files for BIOS update, and there are two different versions of the chip, which can be 1M or 2M, in the MB I have there is the 1M one (MX 28F1000PPC-12C4 chip), for this chip I have three different versions I choose the latest (most recent), it is used to update the Micro Code and fixes a compatibility problem with the ATI and TNT video cards, the installable CPUs arrive at the Celeron 500 and the PIII 600, but perhaps this depends on the Since these were the fastest CPUs available back then, maybe it's not hard for faster CPUs to run smoothly.
At the moment I'm still here, I have to prepare and put the file on a blank floppy, connect a 1.44MB floppy reader and an AT keyboard, then I have to reboot and see if the BIOS resets, in case it doesn't update I should see to do a reprogramming the chip, or finding a new chip and programming it with the right file, there would be a third shorter route, hot reprogramming using another PC with the same BIOS chip socket, is risky but fast enough and effective if done in the correct way you find yourself with two PCs working, otherwise if something goes wrong and you are wrong, having bad luck you find yourself with both PCs knocked out.

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AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 95 of 137, by PC@LIVE

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Lately I have been trying to recover various motherboards that I have been keeping aside for a few years, just recently I fixed a couple of Slot1 BX, while in the next days I should try to rewrite the BIOS of the PINE SI21, I remember that it is a baby-AT Slot1 chipset SiS, by far it is worse in terms of performance than the BX, but it is very convenient for those who have an old case and want to build a PC from the late 90s, no matter whether the case is AT or ATX, it fits both having two sockets for connect the power supply.

I am going to show you a card that I have been checking lately, it is a slightly newer card, it is an ASRock 775i65G REV. G / A 2.03, has AGP PCI and AMR ram ddr slots.
after several attempts with RAM ddr400 and CPU Celeron D 331, I always get the same result, it starts up but the post card always displays - -, the voltage LEDs are all on and also the CLK one, the reset one when starting flashes and yes turns off (this is normal).
I check the voltages of the various mosfets and everything seems normal, at this point I think I clean the RAM and CPU contacts, and in the CPU socket I find many twisted PINs, a clear sign that they have been straightened, a couple in my opinion do not make contact or they do it badly, others should be better positioned.
Maybe if I can have some suggestions on how to fix them, it would be of great help. Thanks in advance

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AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 96 of 137, by PC@LIVE

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In the next few days I should be able to restore the BIOS of the PINE SI21, I am gathering everything that is needed to fix it, I just have to create a special floppy for recovery, in the meantime I have identified the type of BIOS (v4.51PG) and I have checked that the file is actually for that card, from what I've seen it looks like it, but in case I have other older versions that you can use.

While I'm on the subject of BIOS, update and recovery, I'll see if I can get some card going, which makes me doubt its actual operation, for example I repaired an ASUS P5KPL SE REV some time ago. 2.01G, the maximum it displays with the POST CARD is 00 -, from researches it is possible that it may be due to an incorrect BIOS update, I will try to remove the chip and check it with a programmer, if the content is broken, I would try to rewrite it with a version downloaded from the ASUS website.

Attachments

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 97 of 137, by PC@LIVE

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A little while ago I ran the awdflash program on the PINE SI21, honestly I didn't understand much, from what I understand it might not have done anything, but I didn't do any other startup tests, at the moment with the ISA card the floppy starts without problems, I don't understand why it says "Unknown Flash Type!", I don't understand if the awdflash program used is wrong?
If there are any suggestions, they would be very useful to me, I honestly did not understand if the problem is the BIOS chip, or the file in it?

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AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB

Reply 98 of 137, by PcBytes

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Try Uniflash. It should very likely be able to find and flash the chip. The reason I say this is because AWDFLASH might be restricted to a certain range of chips while UNIFLASH supports all of them.

"Enter at your own peril, past the bolted door..."
Main PC: i5 3470, GB B75M-D3H, 16GB RAM, 2x1TB
98SE : P3 650, Soyo SY-6BA+IV, 384MB RAM, 80GB

Reply 99 of 137, by PC@LIVE

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PcBytes wrote on 2021-12-17, 20:30:

Try Uniflash. It should very likely be able to find and flash the chip. The reason I say this is because AWDFLASH might be restricted to a certain range of chips while UNIFLASH supports all of them.

Thank you so much my friend. In fact I had forgotten that that program could have solved the problem, and you are right that could be the problem for not recognizing the chip, I'll see if I can use UNIFLASH today, in case I think by tomorrow I can finish writing the BIOS.

I saw that you have signed a SOYO card the same as the one I repaired, you can see it in previous posts, it is currently under construction, for now I have a PII 300 and 32MB of RAM, but I should put more RAM and another CPU more fast, maybe if I can I put a PIII-370 with adapter.

AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB