Recently, i posted about 386 stuck at wait. I fixed it by removing coprocessor or by just disabling fpu test in bios (but dos refuses to work), so is it coprocessor or motherboard trouble? (i am really afraid). My m/b is seritech 386 ad iii
Well, are you sure about the FPU being healthy?
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dominusprog wrote on 2024-09-20, 10:12:Well, are you sure about the FPU being healthy?
Not sure, its missing one leg and after removing pc boots normally.
after hard reset pc boots and passes fpu tests (with fpu) but in first start (before reset) it stuck at wait
Which pin is it? Can't you solder a piece of wire on to it?
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dominusprog wrote on 2024-09-20, 10:53:Which pin is it? Can't you solder a piece of wire on to it?
i dont think so as i dont really can solder those tiny pins. I dont have such small soldering iron
pin is left upper (first row of pins)
Insert a piece of wire into the socket, cut the top and install the FPU.
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is the missing pin reset by any chance?
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https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
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dominusprog wrote on 2024-09-20, 11:36:Insert a piece of wire into the socket, cut the top and install the FPU.
Installed. Same thing
Can you post a photo of the FPU?
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dominusprog wrote on 2024-09-20, 13:18:Can you post a photo of the FPU?
Sorry i cant, its iit 387-40
Add a little bit of solder to the broken pin and try again. Also use a contact cleaner on the socket.
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You may have luck when a resistors leg fits into your FPU socket. They use to have enough stiffness.
Then you may cut a bit off and solder it on that pin. It should have same length than your other pins.
I think fpu is just broken because previous owner programming using cos and sin. Maybe he sell this for cheap because of fpu as he need it
i replaced missing leg with solder, finally, after 1 hour...
daniil1909 wrote on 2024-09-20, 10:17:.... its missing one leg and after removing pc boots normally.
daniil1909 wrote on 2024-09-21, 04:05:i replaced missing leg with solder, finally, after 1 hour...
OK. Does the FPU work now?
So the board works fine without it. Do you need an FPU ?
The motherboard working proper is main thing, everything else added is secondary IMHO.
Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun
A modern alternative to old bits of resistor leg might be a small cutting of "beading wire" from the crafts aisle at your local supermarket.
I picked up a roll of sterling silver plated copper wire for this exact kind of thing. The silver plating is sterling type (so does not tarnish much), and VERY accepting of being solder-tinned. It's stiff enough for most functions like this, and works great as jumper wire. Available in a wide assortment of gauges.
Only downside is that there is no insulation, so dont use it as bodge wire unless you are very good at applying soldermask or something to the naked wire before running it. It's great for correcting damaged traces though.
(Example of the stuff in question)
https://www.amazon.com/20-Gauge-Resistant-Sup … ref=sr_1_1_sspa
Horun wrote on 2024-09-21, 04:32:OK. Does the FPU work now? So the board works fine without it. Do you need an FPU ? The motherboard working proper is main th […]
daniil1909 wrote on 2024-09-20, 10:17:.... its missing one leg and after removing pc boots normally.
daniil1909 wrote on 2024-09-21, 04:05:i replaced missing leg with solder, finally, after 1 hour...
OK. Does the FPU work now?
So the board works fine without it. Do you need an FPU ?
The motherboard working proper is main thing, everything else added is secondary IMHO.
No. FPU is getting hot as hell
wierd_w wrote on 2024-09-21, 07:46:A modern alternative to old bits of resistor leg might be a small cutting of "beading wire" from the crafts aisle at your local […]
A modern alternative to old bits of resistor leg might be a small cutting of "beading wire" from the crafts aisle at your local supermarket.
I picked up a roll of sterling silver plated copper wire for this exact kind of thing. The silver plating is sterling type (so does not tarnish much), and VERY accepting of being solder-tinned. It's stiff enough for most functions like this, and works great as jumper wire. Available in a wide assortment of gauges.
Only downside is that there is no insulation, so dont use it as bodge wire unless you are very good at applying soldermask or something to the naked wire before running it. It's great for correcting damaged traces though.
(Example of the stuff in question)
https://www.amazon.com/20-Gauge-Resistant-Sup … ref=sr_1_1_sspa
Yeah i had something like this by cutting an pin from wire. It doesn't solder, just fall out
