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First post, by mig81

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Hi, I need your help to switch on this old motherboard ibm xt clone for 8088. There arent common P8 P9 plugs....which kind shuold i use to test it?
Thanks

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Reply 2 of 10, by dominusprog

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You can use any AT power supply, but you should remove the second wire on the P8 connector (+5V) just to be on the safe side.

https://www.youtube.com/watch?v=B_jvQPLj-WE

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A-Trend ATC-1020 V1.1 ❇ Cyrix 6x86 150+ @ 120MHz ❇ 32MiB EDO RAM (8MiBx4) ❇ A-Trend S3 Trio64V2 2MiB
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Reply 4 of 10, by dominusprog

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mig81 wrote on 2024-05-23, 21:39:

Thanks alot, tomorrow i'll try!

Before connecting anything to the board, check all the tantalum caps first.

Duke_2600.png
A-Trend ATC-1020 V1.1 ❇ Cyrix 6x86 150+ @ 120MHz ❇ 32MiB EDO RAM (8MiBx4) ❇ A-Trend S3 Trio64V2 2MiB
Aztech Pro16 II-3D PnP ❇ 8.4GiB Quantum Fireball ❇ Win95 OSR2 Plus!

Reply 5 of 10, by Horun

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Yes use a standard AT supply. The XT PSU board header is slightly different shaped than from 286 and up. You may have some trouble trying to insert the AT psu sockets, usually if you do it at a slight angle it can done....
make sure the black leads are in the middle !

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

Reply 7 of 10, by dominusprog

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mig81 wrote on 2024-05-25, 18:12:

I tried to connect p8 p9 (p8 without +5) and not switch on, no beep, only a little fash on the mobo led. If i comnect only p9, mobo led lights and beeps furiously.
Any ideas?

What kind of beep? Continuous beep can be the result of a short on the motherboard, have you checked the tantalum caps?

Duke_2600.png
A-Trend ATC-1020 V1.1 ❇ Cyrix 6x86 150+ @ 120MHz ❇ 32MiB EDO RAM (8MiBx4) ❇ A-Trend S3 Trio64V2 2MiB
Aztech Pro16 II-3D PnP ❇ 8.4GiB Quantum Fireball ❇ Win95 OSR2 Plus!

Reply 8 of 10, by mig81

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Continuous beep...but I think it's because I have to connect even p9. On the board i cannot see tantalium caps....if i cannect p8 and p9, no beeps and only a little flash of the mobo led. I think there is a short and the power supply is blocked by the mobo...cpuld be?

Reply 9 of 10, by dominusprog

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mig81 wrote on 2024-05-25, 20:10:

Continuous beep...but I think it's because I have to connect even p9. On the board i cannot see tantalium caps....if i cannect p8 and p9, no beeps and only a little flash of the mobo led. I think there is a short and the power supply is blocked by the mobo...cpuld be?

So you've connected a power supply without checking it first? The tantalum caps are beside the keyboard connector, you have to check them all (which include the blue ones) with a multimeter.

Duke_2600.png
A-Trend ATC-1020 V1.1 ❇ Cyrix 6x86 150+ @ 120MHz ❇ 32MiB EDO RAM (8MiBx4) ❇ A-Trend S3 Trio64V2 2MiB
Aztech Pro16 II-3D PnP ❇ 8.4GiB Quantum Fireball ❇ Win95 OSR2 Plus!

Reply 10 of 10, by mig81

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dominusprog wrote on 2024-05-26, 15:56:
mig81 wrote on 2024-05-25, 20:10:

Continuous beep...but I think it's because I have to connect even p9. On the board i cannot see tantalium caps....if i cannect p8 and p9, no beeps and only a little flash of the mobo led. I think there is a short and the power supply is blocked by the mobo...cpuld be?

So you've connected a power supply without checking it first? The tantalum caps are beside the keyboard connector, you have to check them all (which include the blue ones) with a multimeter.

Ok man, tomorrow I'll try to check all the caps with a multimeter fir capacitors, i should have one. Thanks