mkarcher wrote on 2022-09-12, 14:47:

Good news: These values are the ones that I need to get to a conclusion. Bad news: These values all look fine, so it doesn't loo […]
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biessea wrote on 2022-09-12, 12:38:

If I have understood good I re-tried to measure the diode test and write down all the results:

[...]

I hope it gives you more interesting indication.

Good news: These values are the ones that I need to get to a conclusion. Bad news: These values all look fine, so it doesn't look like your issue is caused with the low address bits of the RAM.

I'm sorry, but at the moment I am out of ideas what to try with the equipment and skill you currently have. The board is very close to working fine, but somewhere is a minor fault, and it is difficult to locate that fault. The next thing I would do if it were my own board: Use an ISA POST card to trace the progress of the self test, and disassemble the BIOS (after reading it in an EPROM reader) to find out what specifically the BIOS is doing before it goes beeping. That means: In this scenario of remote debugging, I have to give up.

Your 386DX-40, the coprocessor and the RAM are still good components, and assuming the fault is on the board (which is quite likely), I would keep looking at ebay, craigslist or similar for another 40MHz-capable 386 board for an acceptable price.

Hey but, if I buy a IDE-ISA post card can you have more ideas then?

It will worth what do you think?

I have a USB bios programmer, ch341a, I use to program video card bioses. Can this help to you my dear friend?

biessea wrote on 2022-09-12, 18:28:

Hey but, if I buy a IDE-ISA post card can you have more ideas then?

It will worth what do you think?

I have a USB bios programmer, ch341a, I use to program video card bioses. Can this help to you my dear friend?

Yeah, you can get PCI/ISA POST cards at AliExpress. They will take some weeks to ship, but they work, if you order the good version. The bad ones have a high chance of terminally frying your board without any chance of working in ISA slots. Look out for the cards to have multiple chips. See this thread for examples Troubles between a PCI/ISA POST card and my Asus P55T2P4-C motherboard : The card in the first post of the thread is evil and must only ever be used in PCI slots. The card shown in the fourth post works perfectly in both PCI and ISA slots.

You should be able to dump your BIOS by reading it as 27C512 using the ch341a programmer.

mkarcher wrote on 2022-09-12, 19:15:

biessea wrote on 2022-09-12, 18:28:

Hey but, if I buy a IDE-ISA post card can you have more ideas then?

It will worth what do you think?

I have a USB bios programmer, ch341a, I use to program video card bioses. Can this help to you my dear friend?

Yeah, you can get PCI/ISA POST cards at AliExpress. They will take some weeks to ship, but they work, if you order the good version. The bad ones have a high chance of terminally frying your board without any chance of working in ISA slots. Look out for the cards to have multiple chips. See this thread for examples Troubles between a PCI/ISA POST card and my Asus P55T2P4-C motherboard : The card in the first post of the thread is evil and must only ever be used in PCI slots. The card shown in the fourth post works perfectly in both PCI and ISA slots.

You should be able to dump your BIOS by reading it as 27C512 using the ch341a programmer.

Ok my friend, I just ordered the correct version from Amazon, they probably have it on its european stock.
So it will reach me on thursday and I will immediately install.
How can I use it?
What I have to do?

And what about the USB bios programmer ch341a? It will be useful do you think on this motherboard?

But first I have to try with the post card isn't it?

biessea wrote on 2022-09-12, 21:15:

How can I use it?
What I have to do?

You need to insert the POST card into an ISA slot. Be careful: As that card doesn't have a bracket, you can insert it the wrong way around, which might cause damage to the card or your system. It needs to have the components facing the same way as any other ISA card, like your VGA card. On standard PC/XT/AT mainboards, ISA cards always have the components on the PCB side that is closer to the mainboard power connector.

When you power on the computer with the POST card installed, it will show numbers to you that indicate the progress of the boot process. On that specific model of POST card, the current code is shown on the first two digits, and the previous one is shown on the other two digits. For analyzing the problem, likely only the first two digits are interesting. https://www.youtube.com/watch?v=ggoUkEjkvwg is a YouTube video that explains how to use a POST card, and shows how it is installed in a computer.

biessea wrote on 2022-09-12, 21:15:

And what about the USB bios programmer ch341a? It will be useful do you think on this motherboard?

But first I have to try with the post card isn't it?

I'm sorry that I did not check what the CH341A actually is. It does not support BIOS chips from earlier than around 2005, so you can not use it to read the contents of your BIOS chip. It's not that bad, likely, because in many cases, the BIOS of a similar board that already has been published to the internet is good enough as reference what the BIOS is doing at a certain stage of the boot process. A device that would be able to read your BIOS chip (that's the chip next to the keyboard controller with the sticker on it) would be the MiniPro TL866. But please don't go spend money on that device yet. It is only required if we can't find out another way what the computer is doing when it enters the endless beep loop.

mkarcher wrote on 2022-09-14, 19:15:

You need to insert the POST card into an ISA slot. Be careful: As that card doesn't have a bracket, you can insert it the wrong […]
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biessea wrote on 2022-09-12, 21:15:

How can I use it?
What I have to do?

You need to insert the POST card into an ISA slot. Be careful: As that card doesn't have a bracket, you can insert it the wrong way around, which might cause damage to the card or your system. It needs to have the components facing the same way as any other ISA card, like your VGA card. On standard PC/XT/AT mainboards, ISA cards always have the components on the PCB side that is closer to the mainboard power connector.

When you power on the computer with the POST card installed, it will show numbers to you that indicate the progress of the boot process. On that specific model of POST card, the current code is shown on the first two digits, and the previous one is shown on the other two digits. For analyzing the problem, likely only the first two digits are interesting. https://www.youtube.com/watch?v=ggoUkEjkvwg is a YouTube video that explains how to use a POST card, and shows how it is installed in a computer.

biessea wrote on 2022-09-12, 21:15:

And what about the USB bios programmer ch341a? It will be useful do you think on this motherboard?

But first I have to try with the post card isn't it?

I'm sorry that I did not check what the CH341A actually is. It does not support BIOS chips from earlier than around 2005, so you can not use it to read the contents of your BIOS chip. It's not that bad, likely, because in many cases, the BIOS of a similar board that already has been published to the internet is good enough as reference what the BIOS is doing at a certain stage of the boot process. A device that would be able to read your BIOS chip (that's the chip next to the keyboard controller with the sticker on it) would be the MiniPro TL866. But please don't go spend money on that device yet. It is only required if we can't find out another way what the computer is doing when it enters the endless beep loop.

Perfect, thank you.

The POST ISA/IDE card is just arrived and I am ready to connect it. I have THE SAME post card of the one in the video you linked me. The same one. Nice.

The second part of the message I am not understood well, you tell me I have a too new bios reader I guess...and not to spend other money to buy another one.

Anyway I will give you results in a while...

Hi there,

this is the error code I take every time.

42 - 43

I put photo about.

I have done a little movie too, do you need? This is the link on my Youtube channel:
https://youtu.be/EaOcXqQuP_I
Let me know.

The corresponding error of 43 in AMI bios is "entered protected mode. Enabling interrupts for diagnostic mode next".

the 42 code is "thge descriptor tables are prepared. Enteling preotected mode for the memory next"

What can you tell me now?

biessea wrote on 2022-09-17, 08:26:

42 - 43 […]
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42 - 43

I put photo about.

I have done a little movie too, do you need? This is the link on my Youtube channel:
https://youtu.be/EaOcXqQuP_I
Let me know.

I checked the BIOS from a similar board, and disassembled the relevant parts. Your video looked quite strange to me at first, because the order of POST codes did not really make sense, but I finally detected your real problem: One of the eight data bits on the ISA bus is not working. In particular, it's the data bit D1, which is located at pin A8 on the ISA slot and pin 13 of the keyboard controller. The bit is stuck high. That means: Everytime the processor sends something to the ISA bus, the device reads bit 1 (counting starts at 0) as 1, even if the processor writes 0 into that bit. As the POST codes are sent over the ISA bus, the POST codes displayed on the card are partly incorrect. Also, if the processor tries to read ISA bus data bit 1, it always reads "1", even if the ISA device is sending a zero.

The behaviour of your board makes perfect sense if the trace for ISA D1 is interrupted somewhere, such that the BIOS chip (the one with the AMI sticker next to the keyboard controller) still has a valid D1 bit (otherwise, the BIOS wouldn't run at all), but D1 is missing at the keyboard controller and the ISA slots. Please check continuity for

• ISA data bit 0 between pin 11 of the BIOS chip, pin A9 of the ISA bus and pin 12 of the keyboard controller (I expect everything is connected. This is just to check whether I understand that board correctly)
• ISA data bit 1 between pin 12 of the BIOS chip, pin A8 of the ISA bus and pin 13 of the keyboard controller (I expect the ISA bus and the keyboard controller to be connected, but the BIOS to be separate. That would be the fault on your board)
• ISA data bit 2 between pin 13 of the BIOS chip, pin A7 of the ISA bus and pin 14 of the keyboard controller (I expect everything is connected. This is again for verification).

If you get the results I expect, the fault is clearly identified. D1 should also be connected to pin 3 of U11. U11 was heavily corroded. I see the trace on the backside of the board connecting pin 12 of the BIOS chip to pin 3 of U11. That trace looks fine. I guess there is a trace on the front side of the board connecting pin 3 of U11 to pin 13 of the keyboard controller, and I guess this trace is broken.

mkarcher wrote on 2022-09-17, 19:40:

I checked the BIOS from a similar board, and disassembled the relevant parts. Your video looked quite strange to me at first, be […]
Show full quote

biessea wrote on 2022-09-17, 08:26:

42 - 43 […]
Show full quote

42 - 43

I put photo about.

I have done a little movie too, do you need? This is the link on my Youtube channel:
https://youtu.be/EaOcXqQuP_I
Let me know.

I checked the BIOS from a similar board, and disassembled the relevant parts. Your video looked quite strange to me at first, because the order of POST codes did not really make sense, but I finally detected your real problem: One of the eight data bits on the ISA bus is not working. In particular, it's the data bit D1, which is located at pin A8 on the ISA slot and pin 13 of the keyboard controller. The bit is stuck high. That means: Everytime the processor sends something to the ISA bus, the device reads bit 1 (counting starts at 0) as 1, even if the processor writes 0 into that bit. As the POST codes are sent over the ISA bus, the POST codes displayed on the card are partly incorrect. Also, if the processor tries to read ISA bus data bit 1, it always reads "1", even if the ISA device is sending a zero.

The behaviour of your board makes perfect sense if the trace for ISA D1 is interrupted somewhere, such that the BIOS chip (the one with the AMI sticker next to the keyboard controller) still has a valid D1 bit (otherwise, the BIOS wouldn't run at all), but D1 is missing at the keyboard controller and the ISA slots. Please check continuity for

• ISA data bit 0 between pin 11 of the BIOS chip, pin A9 of the ISA bus and pin 12 of the keyboard controller (I expect everything is connected. This is just to check whether I understand that board correctly)
• ISA data bit 1 between pin 12 of the BIOS chip, pin A8 of the ISA bus and pin 13 of the keyboard controller (I expect the ISA bus and the keyboard controller to be connected, but the BIOS to be separate. That would be the fault on your board)
• ISA data bit 2 between pin 13 of the BIOS chip, pin A7 of the ISA bus and pin 14 of the keyboard controller (I expect everything is connected. This is again for verification).

If you get the results I expect, the fault is clearly identified. D1 should also be connected to pin 3 of U11. U11 was heavily corroded. I see the trace on the backside of the board connecting pin 12 of the BIOS chip to pin 3 of U11. That trace looks fine. I guess there is a trace on the front side of the board connecting pin 3 of U11 to pin 13 of the keyboard controller, and I guess this trace is broken.

Nice, so you have other important clues.

Tomorrow I will check that continuity, and I hope this is the real problem and I hope we'll fix it.

See you tomorrow my dear.

mkarcher wrote on 2022-09-17, 19:40:

I checked the BIOS from a similar board, and disassembled the relevant parts. Your video looked quite strange to me at first, be […]
Show full quote

biessea wrote on 2022-09-17, 08:26:

42 - 43 […]
Show full quote

42 - 43

I put photo about.

I have done a little movie too, do you need? This is the link on my Youtube channel:
https://youtu.be/EaOcXqQuP_I
Let me know.

I checked the BIOS from a similar board, and disassembled the relevant parts. Your video looked quite strange to me at first, because the order of POST codes did not really make sense, but I finally detected your real problem: One of the eight data bits on the ISA bus is not working. In particular, it's the data bit D1, which is located at pin A8 on the ISA slot and pin 13 of the keyboard controller. The bit is stuck high. That means: Everytime the processor sends something to the ISA bus, the device reads bit 1 (counting starts at 0) as 1, even if the processor writes 0 into that bit. As the POST codes are sent over the ISA bus, the POST codes displayed on the card are partly incorrect. Also, if the processor tries to read ISA bus data bit 1, it always reads "1", even if the ISA device is sending a zero.

The behaviour of your board makes perfect sense if the trace for ISA D1 is interrupted somewhere, such that the BIOS chip (the one with the AMI sticker next to the keyboard controller) still has a valid D1 bit (otherwise, the BIOS wouldn't run at all), but D1 is missing at the keyboard controller and the ISA slots. Please check continuity for

• ISA data bit 0 between pin 11 of the BIOS chip, pin A9 of the ISA bus and pin 12 of the keyboard controller (I expect everything is connected. This is just to check whether I understand that board correctly)
• ISA data bit 1 between pin 12 of the BIOS chip, pin A8 of the ISA bus and pin 13 of the keyboard controller (I expect the ISA bus and the keyboard controller to be connected, but the BIOS to be separate. That would be the fault on your board)
• ISA data bit 2 between pin 13 of the BIOS chip, pin A7 of the ISA bus and pin 14 of the keyboard controller (I expect everything is connected. This is again for verification).

If you get the results I expect, the fault is clearly identified. D1 should also be connected to pin 3 of U11. U11 was heavily corroded. I see the trace on the backside of the board connecting pin 12 of the BIOS chip to pin 3 of U11. That trace looks fine. I guess there is a trace on the front side of the board connecting pin 3 of U11 to pin 13 of the keyboard controller, and I guess this trace is broken.

Ok, here I am.

I has the results you expected.

I have continuity between pin 11 of bios chip and a9 on ISA and pin 13 on keyboard controller. All ok.

I don't have continuity between pin 12 on bios and NO ONE a7 ISA slot pin and the pin 13 of keyboard connector.

I have continuity from pin 13 bios chip to pin a7 of ISA bus and pin 14 of keyboard connector.

At the end I don't have continuity between d1 to pin 3 of U11.

What can I do now?

biessea wrote on 2022-09-19, 13:41:

I don't have continuity between pin 12 on bios and NO ONE a7 ISA slot pin and the pin 13 of keyboard connector.

Your photo shows severe damage to some traces. I took a small part and marked the locations where traces look broken. Interestingly, the two locations with the red circle still work, although they look really bad. The location with the red circle doesn't look that bad, but that is the trace we found out to be broken.

One way to fix the the board would be to remove U11 (desolder it), and fix all the traces that look bad. This is a delicate job, and requires some experience with soldering. If you don't have experience yet, don't try to desolder U11, but just add bodge wires on the back. As many of the traces look bad on the photo, I recommand to just add bodge wires to all of the traces:

• pin 2 of U11 to pin 12 of the keyboard controller
• pin 3 of U11 to pin 13 of the keyboard controller
• pin 4 of U11 to pin 14 of the keyboard controller
• pin 5 of U11 to pin 15 of the keyboard controller
• pin 6 of U11 to pin 16 of the keyboard controller
• pin 7 of U11 to pin 17 of the keyboard controller
• pin 8 of U11 to pin 18 of the keyboard controller
• pin 9 of U11 to pin 19 of the keyboard controller

The line printed in bold is the trace that is already broken now. Just adding this one bodge should be enough to get the board working for now, but I'm afraid other traces might break soon, that's why I listed all eight traces. You might want to test that all the non-bold traces are connected as I indicated, just to make sure I didn't mix up pins.

EDITs: sorry for messing around - had to fight image recompression to get a usable picture.

mkarcher wrote on 2022-09-19, 18:13:

Your photo shows severe damage to some traces. I took a small part and marked the locations where traces look broken. Interestin […]
Show full quote

biessea wrote on 2022-09-19, 13:41:

I don't have continuity between pin 12 on bios and NO ONE a7 ISA slot pin and the pin 13 of keyboard connector.

Your photo shows severe damage to some traces. I took a small part and marked the locations where traces look broken. Interestingly, the two locations with the red circle still work, although they look really bad. The location with the red circle doesn't look that bad, but that is the trace we found out to be broken.

bad_traces.jpg

One way to fix the the board would be to remove U11 (desolder it), and fix all the traces that look bad. This is a delicate job, and requires some experience with soldering. If you don't have experience yet, don't try to desolder U11, but just add bodge wires on the back. As many of the traces look bad on the photo, I recommand to just add bodge wires to all of the traces:

• pin 2 of U11 to pin 12 of the keyboard controller
• pin 3 of U11 to pin 13 of the keyboard controller
• pin 4 of U11 to pin 14 of the keyboard controller
• pin 5 of U11 to pin 15 of the keyboard controller
• pin 6 of U11 to pin 16 of the keyboard controller
• pin 7 of U11 to pin 17 of the keyboard controller
• pin 8 of U11 to pin 18 of the keyboard controller
• pin 9 of U11 to pin 19 of the keyboard controller

The line printed in bold is the trace that is already broken now. Just adding this one bodge should be enough to get the board working for now, but I'm afraid other traces might break soon, that's why I listed all eight traces. You might want to test that all the non-bold traces are connected as I indicated, just to make sure I didn't mix up pins.

EDITs: sorry for messing around - had to fight image recompression to get a usable picture.

Ok, I think I understand what you are trying to say to me.

Anyway I could desoldering the u11 chip yes, I did other times, but I don't really know how to fix traces, I never fixed traces in mainboard.

There is a way to fix traces without putting other traces over them like necro did in his Youtube videos?

So at the end you think that all the problems is around the U11 chips so...and what about the ISA bus?

PS: what is bodge wires? I cannot find a translation for "bodge".

biessea wrote on 2022-09-19, 21:48:

There is a way to fix traces without putting other traces over them like necro did in his Youtube videos?

If the gap in the trace is really short, you can try to bridge the gap using solder only. In your case, this might be possible. Be sure to remove the solder mask (a kind of laqcuer) above the traces, so the copper is exposed before trying to fix them. Necroware used a fiberglass pencil, which is a very good tool for that purpose, but even using a miniature flat-blade screwdriver will work. The method Necroware showed in his video is one of the neatest ways to fix traces, so don't hope for anything better.

biessea wrote on 2022-09-19, 21:48:

So at the end you think that all the problems is around the U11 chips so...and what about the ISA bus?

The path from the processor to the ISA bus uses the traces near U11: The ISA data is managed by the UMC 82C482 chip. There are trace from the UMC 82C482 to the BIOS chip (they work). There are traces from the BIOS chip to U11 (they look fine and seem to work, too). There are traces from U11 to the keyboard controller (your recent photo shows: They look horrible near the pins of U11). There are traces from the keyboard controller to the ISA slots (again, they look fine). So fixing the path from U11 to the keyboard controller should communication with the ISA bus as well as the keyboard controller.

biessea wrote on 2022-09-19, 21:48:

PS: what is bodge wires? I cannot find a translation for "bodge".

"bodge wires" are a quick, but often ugly way to deal with broken traces. Fixing the traces like Necroware looks way better. This picture on twitter shows what bodge wires look like: https://pbs.twimg.com/media/EhoTVEKUYAApNdx?format=jpg (the blue wires). It's not the kind of wire that makes these wires "bodge wires", but the way the wires are used. Bodge wires are replacements for broken or missing traces. In the case of the twitter image, a chip soldered on the board has been removed and replaced by the extra PCB, so these new "traces" are needed to connect the extra PCB to the point where the removed chip was.

mkarcher wrote on 2022-09-20, 07:27:

If the gap in the trace is really short, you can try to bridge the gap using solder only. In your case, this might be possible. […]
Show full quote

biessea wrote on 2022-09-19, 21:48:

There is a way to fix traces without putting other traces over them like necro did in his Youtube videos?

If the gap in the trace is really short, you can try to bridge the gap using solder only. In your case, this might be possible. Be sure to remove the solder mask (a kind of laqcuer) above the traces, so the copper is exposed before trying to fix them. Necroware used a fiberglass pencil, which is a very good tool for that purpose, but even using a miniature flat-blade screwdriver will work. The method Necroware showed in his video is one of the neatest ways to fix traces, so don't hope for anything better.

biessea wrote on 2022-09-19, 21:48:

So at the end you think that all the problems is around the U11 chips so...and what about the ISA bus?

The path from the processor to the ISA bus uses the traces near U11: The ISA data is managed by the UMC 82C482 chip. There are trace from the UMC 82C482 to the BIOS chip (they work). There are traces from the BIOS chip to U11 (they look fine and seem to work, too). There are traces from U11 to the keyboard controller (your recent photo shows: They look horrible near the pins of U11). There are traces from the keyboard controller to the ISA slots (again, they look fine). So fixing the path from U11 to the keyboard controller should communication with the ISA bus as well as the keyboard controller.

biessea wrote on 2022-09-19, 21:48:

PS: what is bodge wires? I cannot find a translation for "bodge".

"bodge wires" are a quick, but often ugly way to deal with broken traces. Fixing the traces like Necroware looks way better. This picture on twitter shows what bodge wires look like: https://pbs.twimg.com/media/EhoTVEKUYAApNdx?format=jpg (the blue wires). It's not the kind of wire that makes these wires "bodge wires", but the way the wires are used. Bodge wires are replacements for broken or missing traces. In the case of the twitter image, a chip soldered on the board has been removed and replaced by the extra PCB, so these new "traces" are needed to connect the extra PCB to the point where the removed chip was.

Ok, Thank you master.

I think I have understood, I will try the Necroware method, and if you remember a video where he speaks about and fix a trace can you please link me?

Anyway now I am departing from home, I will go to Oktoberfest in Germany four days. On saturday I will be another time operative listening you on what to do.

Thanks a lot another time, I will do that on saturday and I will make you know.

Loris

biessea wrote on 2022-09-20, 07:34:

I think I have understood, I will try the Necroware method, and if you remember a video where he speaks about and fix a trace can you please link me?

Yeah, of course you can have a link: https://youtu.be/eJ4DlRigKxA?t=196 (links to 3:16) up to 10:30 is all about temporarily removing components and fixing traces.

mkarcher wrote on 2022-09-20, 16:14:

biessea wrote on 2022-09-20, 07:34:

I think I have understood, I will try the Necroware method, and if you remember a video where he speaks about and fix a trace can you please link me?

Yeah, of course you can have a link: https://youtu.be/eJ4DlRigKxA?t=196 (links to 3:16) up to 10:30 is all about temporarily removing components and fixing traces.

Hey my dear, I'm back.

I tried to solder that tracks, this is the result I have done. Better of this for me it's impossibile, I made a lot of effort you kwno, I'm not a solder professionist.

Anyway there is a problem I think, I ask you.

U11 Pin 3 -> K controller Pin13 finally has continuity.
Anyway I don't know why if I connect U11 Pin 5 with K controller Pin13 has continuity too. Is that a short? Or some pins is connected with others?

Can you tell me now please how I can reput the U11 chip in his site please, that I really cannot imagine to?

biessea wrote on 2022-09-29, 13:44:

Can you tell me now please how I can reput the U11 chip in his site please, that I really cannot imagine to?

suck the solder out. You can use soldering braid, shitty manual pump, compressed air if you are brave (will fly everywhere including your eyes), or hypodermic needle (stainless, wont stick to solder)

rasz_pl wrote on 2022-09-29, 16:21:

biessea wrote on 2022-09-29, 13:44:

Can you tell me now please how I can reput the U11 chip in his site please, that I really cannot imagine to?

suck the solder out. You can use soldering braid, shitty manual pump, compressed air if you are brave (will fly everywhere including your eyes), or hypodermic needle (stainless, wont stick to solder)

I just made holes with a 1mm dremel arrow.

I think I have done a mess.

I loose continuity for various other pins.

I attach the image, please how can I repair it now.

I am completely tired of this solding, It's completely a mad work.

I really hope Mkarcher my friend can come and calm me, I'm really angry.

I usually mention not to drill because you will rip out hole plating, too bad I forgot this time 😒
looks like you 'only' ripped 6 pads 😀 Nothing an evening with microscope, a glass of your favorite drink, thin wire and patience cant fix.

biessea wrote on 2022-09-29, 16:31:

I attach the image, please how can I repair it now.

I really hope Mkarcher my friend can come and calm me, I'm really angry.

As it looks now, a lot of traces on the front side are broken. Nevertheless, the board still seems repairable. Trying to fix the traces will be very tedious, delicate and difficult. If I would get the board in this state, I would not care any more about how it looks, just about that it works. I would just add bodge wires to the back of the PCB bridging all broken traces.

It is good that you used a drill bit this fine. Your board is a four-layer PCB. You see the traces on the top and the bottom layer. There are two (mostly solid) copper layers between them, connected to ground and +5V. Those layers have holes where the drilled holes in the PCB (PCB experts call those holes "vias") are. When you drill through a multi-layer PCB, you risk creating a short circuit between the inner layers. As your holes are so small and carefully placed, you likely didn't hit the inner layers.

So the new plan is:

• Find out where the traces on the right hand side of U11 should go to. Those are memory address lines from the chip set. Luckily for you, there are two amplifier/buffer chips for the address lines: U10 for bank 0 and another one (possibly U12 or U13) for bank 1. The buffer chip for bank 0 is on the "far side" from the chipset, the new breaks in the traces are inbetween. The buffer chip for bank 1 is likely on the near side. That means you have DIP chips on both sides of the problem, so you can pull bodge wires from one side to the other.
• Re-Solder U11 pins 10 and 20 only. Make sure you have no shorts between +5V and GND created by that. If you do, look downwards for the emergency workaround procedure.
• Re-Solder all the other pins of U11. Test the pins for shorts to GND or +5V. If there is a short, give up.
• Install the bodge wires for pins 2 to 9 of U11 as I suggested in Re: Ehy guys, what is this? AMD 386 40MHZ, Cyrix co-processor, 8MB RAM...
• Check the traces on the back side connecting pins 11 to 18 of U11 to pins 2 to 9 of U10. If you damaged them by drilling, install bodge wires.
• Install bodge wires from the the chip that drives the address lines for bank 1 you identified in the first step to U11 pins 11 to 18 as needed.

Following these steps likely will put the board back into working condition.

Emergency plan if you created short circuits in the second step: Unsolder pins 10 and 20 again, and try to completely clean the holes. Remove any copper filings from the hole, e.g. by carefully scraping it with the drill bit until the short is gone. Cut the small pin part of pins 10 and 20 of U11, so you can reinstall the chip without putting anything in the holes you just cleaned. Install bodge wires for +5V to pin 20 and GND to pin 10 on the front side of the board. You can easily pick up +5V and GND at the small blue capacitors.

If you have any questions about the procedure, ask them before continuing with guessing.

rasz_pl wrote on 2022-09-29, 17:27:

I usually mention not to drill because you will rip out hole plating, too bad I forgot this time 😒
looks like you 'only' ripped 6 pads 😀 Nothing an evening with microscope, a glass of your favorite drink, thin wire and patience cant fix.

I am sorry guy, but I don't know any other method to pull in a IC whem you have de soldered with the heat gun.