Re: Smoke on 386 Motherboard !!!

Posted on 2024-02-23, 20:08

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You dont even have to replace it, in the eighties there was no power analysis software used when designing motherboards, engineers just sprinkled capacitors on the whim/hunch. but there already was a thing called oscilloscope... and this thing had the ability to show noise on power rail, you know …

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Re: Upgrading a 386SX - some advice!

Posted on 2023-08-04, 18:44

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

even without overclock you'll get a substantial benefit, the cache by itself is already a good improvement. and as i said it's enabled right at boot 😀

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Re: Extending the EISA or PISA bus?

Posted on 2023-02-14, 07:53

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

short answer : it won't be so easy. PISA use 188 contacts... if you plan to make travel signals/clock with more than 20cm of ribbon cable with a passive extender, you'll go into troubles for sure. if you don't want to face noise/crosstalk issues, you'll have to mostly double the number of wire, …

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Re: 3COM 3c509b stopped working

Posted on 2023-02-08, 17:45

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

considering how tin/pins and some traces are corroded it just need some reflow and continuity check. i'm even surprised your rom worked when i saw a so bad socket :D but yes, that's why it work again after the oven. 50°C are enough to get some dilation edit : stop using vinegar, it's only for …

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Re: IBM PS/2 55SX recapped diskette drive still not booting to Reference disk

Posted on 2022-12-09, 02:14

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

you can't really miss it, it's near the flywheel. and if we talk about the same drive (DFP723Dxxx), you replaced 2 capacitors near it.

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Re: IBM PS/2 55SX recapped diskette drive still not booting to Reference disk

Posted on 2022-12-08, 18:12

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

i guess you got a ALPS drive in your 55sx ? It turned out there were some traces around the old caps near the motor that were corroded. Managed to sort that out with a multimeter and a botch wire. After that it happily spun away. Blavius said it. on ALPS drives, sometimes it's even necessary to …

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Re: Bought these (retro) hardware today

Posted on 2022-08-21, 21:54

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

hmm yes, you're right, i forgot the 80 is a 32 bit machine...

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Re: Bought these (retro) hardware today

Posted on 2022-08-21, 03:35

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

luckybob wrote on 2022-08-19, 15:56: Yes, that's a memory expansion for the ps2. Its slower than main memory, but better than a hard disk maybe not slower. mca allow ram access as fast as on motherboard, but i don't know if all ram extension used that feature.

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Re: IBM PS/1 repair

Posted on 2022-05-24, 09:24

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, start by checking the connector itself, if not heavy corrosion. then maybe check solder joint on the video chip itself and video ram. thoses machines are a bit complicated when problem come from motherboard, as mostly all part of the chipset use custom gate arrays.

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Re: IBM PS/1 2011 - Original keyboard problem [Help]

Posted on 2022-05-24, 08:54

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Retromania wrote on 2022-05-23, 22:18: Does anybody know why sometimes it works and sometimes not? i gived you the answer, maybe not very clealry, i admit. your problem is capacitors inside the keyboard, on the controller board.

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Re: IBM PS/1 2011 - Original keyboard problem [Help]

Posted on 2022-05-22, 16:32

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

capacitors, capacitors... and capacitors :D good luck if you've never opened thoses keyboards, i strongly suggest you to follow a tutorial. back some years ago, when some informations were less available, i opened one out of curiosity... and never reassemble it. i don't remember exactly how i did, …

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Re: I'm silly and I bought something new. But it has a problem...

Posted on 2022-05-21, 06:39

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

short answer : yes, you can safely swap them 😀

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Re: Short on ISA slots? Try this.

Posted on 2022-05-04, 22:48

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hamby wrote on 2022-05-04, 21:38: to create a "null" bridgeboard for my Amiga that would give me access to the ISA slots just to be sure i understand what you mean, you already have a pc bridgeboard ? or you want to use isa cards on the amiga itself ?

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Re: Upgrading a 386SX - some advice!

Posted on 2022-05-02, 20:00

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

ohhh i realize i didn't put my contribution here. i successfully upgraded 2 PS/2's with SXLC2 50 and 40 Mhz chip. first is a model 35 (isa) originally with a SX20, successfully upgraded with the SXLC2 50 G50 (without 3,3v mod) , overclocked to 33 MHz. and for bonus, cache is enabled by bios. and …

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Re: How can I safely transplant a 160-pin QFP chip?

Posted on 2022-05-02, 12:17

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

not more than others said :) BUT... a safely thing you can do, is put the donor card in oven for 1 or 2 hours at 50/60°C before desoldering. why ? because of moisture. strongly heating old chip that have been in storage for long can have absorb moisture. and when you strongly heat them, mositure …

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Re: Anyone know the polarity on the 3 leg tantalums in an IBM PS/2 type 8525 (Model 25). Color monitor/8086

Posted on 2022-02-13, 01:09

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

yes, a bit off topic, but still useful i guess 😀 they're also not custom made for ibm. you can still buy 3 legged tantalum from digikey for exemple. they're only not widely used, it's different. but to confirm what i said : https://i.stack.imgur.com/oqEyK.png

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Re: Anyone know the polarity on the 3 leg tantalums in an IBM PS/2 type 8525 (Model 25). Color monitor/8086

Posted on 2022-02-12, 20:56

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

no, they're not "pass" or anything else special. 3 leads just give the ability to not care about the way you mount them. in any way, you can't be wrong. that's all. i replaced thoses in a model 30 8086 by regular aluminium without any issues. You seem to think there were some new guys on the …

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Re: Anyone know the polarity on the 3 leg tantalums in an IBM PS/2 type 8525 (Model 25). Color monitor/8086

Posted on 2022-02-11, 22:25

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I disagree with the "Replacing 3-legged with 2-legged" on that page. You have 3 leads because it's a pass capacitor after all. no, they're not "pass" or anything else special. 3 leads just give the ability to not care about the way you mount them. in any way, you can't be wrong. that's all. i …

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Re: Dead Voodoo 1 with visibly degraded components.

Posted on 2022-01-23, 14:44

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

you can also check continuity of corroded vias, some of them are probably cut. very strange corrosive attack...

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Re: IBM PS/2 80 Series motherboard

Posted on 2021-11-29, 00:12

by

by whaka

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Different PS/2 models used different floppy drives interfaces even the bezel to match is different too! eg: 55SX, 70, 80, 85, 95, 77 used different floppy interfaces pinout. just to precise, there's only 2 type of drives. (or maybe 3, with the strange "asterisque" story, but nothing to concern here …

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