VOGONS


First post, by Jester

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I have a 386 mobo with ATX to AT converter cable, and for a while it worked fine. Then last week I got eight beeps when booting which is the AMI bios code for no video card recognized. So I tried reseating the cards and occasionally it would boot. Sometimes I would hear it counting the ram and booting fine but the screen was black. The only way I can get it to boot every time is to only use 8 bit isa cards. As soon as I put a 16bit io card or video card, it fails everytime.

Should I be looking to buy a AT p8 p9 style psu or maybe just build my own converter cable that can do the -5v rail?

Last edited by Jester on 2023-09-03, 13:47. Edited 1 time in total.

Reply 2 of 10, by Horun

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Can you post a picture or link to your motherboard ?
sarcasm: you have the fastest XT class machine 😁

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. https://archive.org/details/@horun

Reply 3 of 10, by Anonymous Coward

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Check the pins in your isa slots. Maybe one of the slots is broken.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 4 of 10, by Jester

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Anonymous Coward wrote on 2023-09-02, 23:55:

Check the pins in your isa slots. Maybe one of the slots is broken.

Can I put deoxit in the slots then reseat the cards the same way I would clean a dirty potentiometer dial on an old stereo?

The thing is it does this 16bit Isa thing on all the slots.

Reply 5 of 10, by Jester

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Horun wrote on 2023-09-02, 21:41:

Can you post a picture or link to your motherboard ?
sarcasm: you have the fastest XT class machine 😁

I believe it’s this Pine Technology board.

https://theretroweb.com/motherboards/s/pine-t … chnology-pt-311

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Reply 6 of 10, by Jester

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jakethompson1 wrote on 2023-09-02, 19:59:

It doesn't sound like the kind of issue that would be fixed with -5V. Is there some leftover corrosion from a barrel battery?

This is very possible.! I remember replacing the old battery with a cordless phone battery some time ago. When I get home I’ll take a picture .

If the corrosion has ate through the circuit, can I just apply some solder and “reflow”? This might be the printed part of the circuit board that damaged the sandwiched layer.

Would be a shame if I have to trash the thirty year old mobo, it’s come so far! The 30pin ram clips already started to break where the metal retainer clips meet the old plastic. Took care of that with zip ties 🤣

The -5v rail is indeed a very separate issue. I have the SB CT1350B sound card, and even if I use a first generation ATX psu, the sound garbles and pops when playing Doom. I guess the converter isn’t relaying the -5v ?? The PSU is a sparkle FSP250-60ATV at the moment, but I tried three different psu's so far with and without the -5v rail and the SB 2.0 issue and the no video issue is the same , so right now I’m leaning towards corrosion around the barrel battery possibility.

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Reply 7 of 10, by Jester

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I took everything apart and noticed that the oxidation from the battery leak

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got worse. I think it ate through that voltage rail. Is it trash now? I can boot fine using a trident card that uses less pins on the ISA slot, but the mach64 uses every pin on the slot so it just doesn’t boot and gives eight beeps.

Shame. It was working fine this time last year and it’s been two years since I removed the old barrel battery and cleaned it up. Somehow the oxidation inside the silicone sanwhich just deteriorated anyways.

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Reply 8 of 10, by megatron-uk

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It can be fixed, but you need to act now. Look at the state of the keyboard port shield - it's covered with discoloration from the battery leak.

You may need to desolder some of those components around that area - clean with an abrasive like a fibreglass pen, fully neutralise any leaked fluid and then repair any traces, if it is just the voltage rails then they're pretty fat and easy to repair with a short section of wire.

The longer it is left, the worse it will get, until it is past the point of repair.

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Reply 9 of 10, by rasz_pl

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imo this repair would require desoldering chips, maybe even ISA slot. its not the power missing that is causing lack of 16bit operation, some data traces eroded somewhere further in.
Much easier and faster selling it for parts and getting something working

Open Source AT&T Globalyst/NCR/FIC 486-GAC-2 proprietary Cache Module reproduction

Reply 10 of 10, by Jester

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megatron-uk wrote on 2023-09-04, 18:05:

It can be fixed, but you need to act now. Look at the state of the keyboard port shield - it's covered with discoloration from the battery leak.

You may need to desolder some of those components around that area - clean with an abrasive like a fibreglass pen, fully neutralise any leaked fluid and then repair any traces, if it is just the voltage rails then they're pretty fat and easy to repair with a short section of wire.

The longer it is left, the worse it will get, until it is past the point of repair.

I’m going to try jumping that section of broken voltage rail to see if that is the main concern and fixes the issue. Not sure which gauge wire is ideal or if there are examples anywhere ?? Otherwise yeah, it’s fit for the pit. I already built another 486 system meanwhile because I was too anxious to play some Fuzzys World of miniature Space Golf. That missing -5v rail on the p8/p9 power converter keeps irking me though. I might order the ceramic resistor to modify it. I also have an Isa awe32 and it is giving me garbled sound too!