VOGONS


First post, by PC@LIVE

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TK-82C390A-4N-D11SE 386DX motherboard test, 128KB L2 cache, UMC chipset, 4MB RAM 30PIN, AMI BIOS.
In recent days I have fixed the two broken tracks of the socket for the keyboard plug.
The work was not complicated, the tracks are large, then I changed the socket for the keyboard with another (recovered), finally I soldered 2 wires for the new 3.6V battery, this serves to distance it, and avoid in case of loss, further damage.
By connecting the indispensable ie Power Supply. ISA Video Card, ISA POST CARD, ISA Keyboard and Controller, I try to start and it seems to be ok, but at some point it starts to beep, counting them are six, which correspond to an error of the keyboard controller 8042 - Gate A20.
The beeps start when the post card shows 08 07 in the display, then they continue and the card changes display passing to 00 08, a sign that something still manages to do, unfortunately at this point there is no display of any video signal.
I remove after turning off the keyboard plug, and restart, now the post card shows various codes in the display and the six beeps are no longer heard, but then it stops at 43 42 and starts to beep continuously, also I have a video signal in which I can read SYSTEM HALTED, I guess it is preceded by FATAL ERROR, the 43 corresponds to Detect Initialize Port, here it stops whether the ISA controller is present or removing it.
Returning to the problem of the Keyboard controller 8042, in this MB the chip is signed LT38C41, I do not know if it is an equivalent chip and if it is a programmable chip, in any case if he was the cause of the problem (the six beeps), I would have a chip of a motherboard 386DX scrapped in the years 2000, this is signed NEC 8907P7 D80C42C161 ATI KBD-3, if it is compatible and does not require special programming could I try it ??? The chip is like pinout identical, but I don't know if it's the same electrically.
Unfortunately not being able to view any BIOS screen, I can't see the make and model of the motherboard, this could be useful to check the jumpers, in case there is some wrong setting, from a search I did it is very similar to Gigabyte GA-386UM 33/40, but some jumpers (near the battery) seem to be different, then there is a J8 which here is W9, the W9 has no jumper (should it be put?) And the serigraphs read ON-Color. ..

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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 1 of 10, by PC@LIVE

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In recent days I have been looking for info on the keyboard controller, in this case it is the LANCE CORP chip. LT38C41, from what I found there are no compatible alternatives in case of chip failure, you have to use an identical chip, I don't know if another chip could be compatible, but I only have a NEC D80C42C chip available.
Having fixed the two corroded and interrupted tracks, he restored the electrical connection with the DIN connector.
I have checked other connections with the controller chip and they are ok. Ditto the fuse and some SMDs (resistors) in the area, even the 4 diodes are ok.
The problem seems to be due to a bad connection (oxidized?), This is because when turned on the three leds of the keyboard turn on and off (regularly), so at this point the next thing to do is remove the controller chip, and clean the PIN of the chip and socket.
From what I have learned underneath that controller chip, there may be another chip, and in case you have to see if there is oxidation there.
But looking at the back of the socket you don't see any other pins, so I don't think there's another chip, but I'll check.

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 2 of 10, by PC@LIVE

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A little while ago I removed the controller chip, as I imagined there is no other chip underneath, and I do not detect any oxidation.
Once the chip has been removed, a screen-printed message appears (visible in the photo), 8742 Keyboard controller, it also says J08-4017C, but I don't know what it means.
At this point, it remains only to clean the contacts well, and reassemble the chip, hoping that it will be enough to solve the problem.
But it's a job I'll do tomorrow.
Looking closely at the enlarged image, I notice that a track that reaches the chip is interrupted, being very small it was difficult to see, I think that by repairing it everything should be okay, and the PC can boot normally.
Obviously, I will also do this work tomorrow, and when the work is finished I try again to start the PC on the desk.

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 3 of 10, by PC@LIVE

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Update on 386 motherboard:
Today I solved, the problem as I thought was a bad contact.
What looked like a broken track was perfect, there was dirt on it and it looked broken.
Before reinserting the keyboard controller chip, I passed the PINs on a fine sandpaper, after the operation the PINs were like new.
When I turned on the PC, I heard several tac tacs and two beeps, on the screen I had access to the BIOS screen, by entering I could set various settings, but at the moment I was interested in getting to the OS start screen.
Exiting the BIOS screen, without memorizing the change (I will do it later), the PC points out the absence of a boot disk, at the moment I do not have the values ​​to enter (head cylinders etc ...).
From the main screen of the BIOS, in the bottom line, there is useful information to understand the manufacturer of the MB, I will check what it corresponds to.
Now I have to find the info for the 128MB CF (used as HD), and load DOS and WIN3.X, currently I don't have the coprocessor, but I think I order one, I have to choose whether the ULSI or the IIT, I choose these because they are both 40MHz, while i387 maxes out at 33MHz, so it should work asynchronously.
For the moment I want to configure it to make it work and usable, later I think to increase the RAM to 8MB and change the VGA ISA to a better one.
I also have various cards to plug in, including SB16 3COM-LAN and modem.

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 4 of 10, by PC@LIVE

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Today I made further progress, in the configuration of the PC, I added the ISA sound card (SB16 Value CT2770), but I had to move the controller to the ISA4 slot, because in the ISA2 slot there is a crystal that prevents correct insertion, that is the ISA card touches the quartz and remains raised.
I made a further progress with the 128MB CF, installing it in another PC (PCChips M810LR Athlon 800), I detected the values ​​of Cyln Head Sec, the capacity on the ATHLON800 is 128MB while on the 386DX by entering the same values ​​it switches to 123MB.
The numbers found are these: Cyln 980; Head 8; Sec 32.
Unfortunately on the 386DX I have an error (see photo), the operating system does not start, I have to understand what it depends on, that is, if it is a software problem (as I imagine) or the numbers entered in the BIOS are not good?

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 5 of 10, by PC@LIVE

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With the 386DX-40 I verified the start of the operating system, thanks to the CF taken from the 486DX2-66, in this there is already installed both DOS and Windows 3.1, plus other programs both Windows and DOS, among those for DOS there are various bench programs, I have used some but only one two three work, through these I realized that the PC probably works with the Turbo off, this is because it goes at about 20MHz instead of 40MHz.
So I have to format and make the 128MB CF bootable, but I would like to install DOS version 5.0 and Windows version 3.0, this is because they take up less space on the disk and because they were the ones used at that time on the 386, but to be honest the warranty seal indicates that MB of 04-1993 so W3.1 already existed.
The only doubt is if W.3.0 supports audio or multimedia, honestly I don't remember, but I think so, maybe not directly but with special programs (I guess), after I have to see for the drivers if specific ones are needed, not I think they are hard to find, in case I will try to find those for VGA Audio etc ...

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 6 of 10, by PC@LIVE

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The faulty search and repair work on the 386DX motherboard is practically done.
I was unable to get the SanDisk 128MB CF card to work, I thought it was a solvable problem, but it seems it is not recognized by the BIOS, because booting from floppy (A: \) it does not find the C: \ (CF) drive, maybe it is possible that it works on other PCs or with PCs with different BIOS (not AMI), so I'll try to order one with a capacity of around 256MB but not SanDisk.
Currently I have on a Canon 8MB CF, where I have installed a DOS version 4.01 (or 4.00?), I am trying to put a Windows version 1.03 in it, unfortunately the free space is not much, with DOS I have occupied about 1MB, currently I have about 4MB free, because I have installed a couple of bench and word processing programs.
However, the 8MB CF will work fine in PCs older than the 386, at most I would say an 8-10 MHz 286.
For a 386-40 you need something larger, at least 100MB, to install DOS 5.0 and W3.X.
So I think to switch shortly to a MB 486, I will try to solve the problems it has and fix it, I will choose one of the various MB486s I have, I think I start with a VLB with 486DX-2-66 and L2 cache not working (see photo).

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 7 of 10, by PC@LIVE

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Today I rebooted the 486 VLB motherboard with faulty L2 cache, the PC only works by disabling it, but the performance is obviously a bit poorer.
I remember that when it worked I had increased the quantity from 128KB to 256KB, adding the chips where they were missing and resetting the jumpers.
Today I tried to remove the chips and clean the oxide from the PINs, unfortunately despite the cleaning (which doesn't hurt) the problem is still present, that is, it has not been solved.
From the ISA post card I read in displays 96 and 95, so something happens at this point (96), I have to investigate exactly to understand what it is that creates the problem, I would exclude that they are the defective cache chips, because the ones I had added work, but it should be try these if they work in another MB, or you would need to test them somehow.

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 8 of 10, by PC@LIVE

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Between yesterday and today I started work on another 486 motherboard, however it is an ISA card (not VLB), it is a practically new card, hardly ever used, originally had a Cyrix DX2-80 CPU and it worked a couple of days, later it showed a blocking problem, and went to the assistance a couple of times, unfortunately they did not solve the problem, from a check done years later the CPU was found to be faulty.
I remember trying other CPUs many years ago, and the card would boot up displaying the BIOS screen, but it couldn't complete boot, that is, it didn't get to the OS loading.
Now I'm trying to get it back into operation, so why would it be nice to fix it, the small size allows installation in a mini-case, for power supply I would use a compact ATX (I don't remember what they are called) with ATX-AT adapter, the installable RAMs are both 30PIN and 72PIN, and if you want you can use both.
As a test CPU I am using a 486SX-25, alternatively I have another one plus a 486DX-33, these CPUs should be working, I have tried all three but the result when starting is the same, the post card always marks - - - on the displays, the keyboard LEDs flash and the floppy seems to start up, but I noticed a couple of things that maybe prevent it from starting, the lack of the 3.6V battery and an interrupted track in the back, this is perhaps not so much important because it goes from the pin of the keyboard chip (which is not present) to the pins of the keylock.
As a VGA I use an ISA CL-GD5420, I thought it had 256KB of memory, as it has two chips marked HY524800J-70, actually it looks like the memory is 1MB, while the I / O controller is still ISA with a winbond W837871F chip , for the ram I tried one from 4MB to 72PIN, but I will change it right away, and I'm using four to 30PIN of 1MB each, on two chips says NEC424256-70, on the third NEC D41256L -85.

Tonight I added the battery to see if it starts, unfortunately nothing has changed, so I don't know I'll try to fix the track in the back, but I don't think anything changes.
The symptoms of this motherboard are the same as many other bad cards that I have, unfortunately the post card is not able (in these cases) to understand what the problem may be.
Returning to the MB Opti 486, I ran other tests, to understand if the cache problem is solvable.
Unfortunately I didn't write down the BIOS setup when it worked fine, so I thought it might be some BIOS entry that needs to be changed to fix the boot hang problem.
But it is not easy there are several attempts to make, because some items have different values, I'll try to understand which ones are to be set, otherwise I would waste time for nothing.

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 9 of 10, by PC@LIVE

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Today I recovered another MB, it is a GMB-386SAL, basically a 33 MHz 386SX.
I had discarded it about twenty years ago, it had a problem starting, it made several beeps, in recent days I disassembled it to clean the oxide and remove the battery (now exhausted).
In the afternoon I tried it, and I discovered that the problem was due to dirt or oxide, it started without problems, and the beeps emitted are due to the low battery (nothing strange then).
For the tests I used the ram present, two pieces of 1MB each at 30 PIN, so in total there are 2MB, as a VGA I put a Hualon ISA with 256KB.
Next I put an ISA controller, to which I will add a CF-IDE adapter and a CF instead of the mechanical HD.
I put some photos to see how it is, unfortunately there is not much possibility to expand it, at the limit I could bring the RAM to 4MB, add a sound card and bring the VGA to 512KB (adding a couple of chips), I remember that there were some chip for the upgrade of the cpu (mounted on top), in practice it went from the 386sx to a 486slc, but perhaps it is easier to win the lottery than to find one (today).

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 10 of 10, by PC@LIVE

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In recent days I have increased the RAM to the 386-SX PC, I had only 2MB (two pieces of 1MB each 30Pin), I have added another 2MB with RAM of the same type (3 samsung chips), in total I now have 4MB, which is the maximum installable using 1MB modules, if I had a couple of 4MB modules each I could instead reach 10MB (2+8 😎 ), or reach 16MB with 4 modules.
within a couple of months I should get some 256MB CF cards, if they do not create problems at boot I will use them as hd and I should install DOS 5 and Windows 3.0.
soon I will add an ISA sound card, I have to choose one of three available, maybe I think to put one with AZTech chip (V 5.0).
tonight I rebooted worked on the Pentium 60 skt4, I finally managed to get it started from Hd and I ran some diagnostic programs, including HWInfo.
The card has only a couple of problems, the DALLAS DS12887 chip has a low battery, so it must be replaced or modified, the other problem is the 1MB CL GD5434 integrated video card, the card with the connector for the monitor is missing (VGA port ), I could make one with parts recovered from scrap MB, and try to understand how to connect the various PINs, but at the moment I use a 2MB vga pci SIS 6215, the more or less we are there.

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