Embarrassing mistakes made restoring this Biostar 486 motherboard

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In this video we are restoring a 486 Socket 3 motherboard, and we are trying to fix several issues. Some of the highlights include:
- Replacing the ODIN RTC module of a 486 motherboard Biostar MB 1433 50UIV with an NWx287 CR2032.
- Accidentally inserting my 486 DX 33 CPU the wrong way in and killing it.
- Trying to get my 486 DX2 66MHz CPU to work, which stubbornly refused to do so...
- Trying to fix a very embarrassing issue with both L1 and L2 caches not working on my 486 DX2 66MHz CPU, which turned out to be the Turbo jumper...
- Adding some thermal paste to the voltage regulation transistor and attaching it firmly against the PCB for better cooling.
theretroweb: theretroweb.com/motherboards/...
NWx287 CR2032: github.com/scrapcomputing/nwX...
Original NWx287: github.com/necroware/nwX287
Necroware's channel: / @necro_ware
Necroware's NWx287 video: • Ultimate RTC module r...
CPUSPD: www.vogons.org/viewtopic.php?...
Phil's DOS Benchmark Pack: www.philscomputerlab.com/dos-...
CPU World: www.philscomputerlab.com/dos-...
Music: Track Stalker from the Duke Duke Dance Party Album
by the Space Quest Historian, Troels Pleimert
spacequesthistorian.bandcamp.com
Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) creativecommons.org/licenses/...

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Опубликовано:

19 авг 2023

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Комментарии : 42

@Choralone422 10 месяцев назад

I'm glad you share your triumphs along with your mistakes. This vid reminds me of the time I accidentally plugged an AT power connector on a 486 board the wrong way. Toasted the board, but the PSU didn't seem to mind at the time! Luckily, the machine had other issues and needed a MB replacement anyway. It was quite the learning experience!

@scrap_computing 10 месяцев назад

I have not got the power connector in the wrong way yet, but I am pretty sure it will happen some day :D

@Takeshi.Nakagawa 10 месяцев назад

The Turboswitch… 😅 I also wouldn’t have expected that as well. And thanks for inserting your error with the CPU, I assume most of us have done it also once. I also killed a 486 in the late 90s in the same way. 😢

@scrap_computing 10 месяцев назад

I assumed that bridging the Turbo contacts with a jumper would result in high performance mode. It turns out I was wrong :) Yeah, I guess it is quite common. At least I destroyed a pretty common DX33 :) It could have been worse.

@Takeshi.Nakagawa 10 месяцев назад

@@scrap_computing this is what I learned a lot of years ago, that basically all Boards with Turbo do run normal and activating "Turbo" makes it slow... 😳 Yes, I made this face also.

@RetroJayKay 10 месяцев назад

Sorry for your loss. But cool to know that the Turbobutton also seems to disable (at least on this board) the 1st and 2nd level Cache. This was new to me.

@scrap_computing 10 месяцев назад

Thanks, RIP DX33 :) Same here, I think I had head about it, but I didn't have first hand experience. I always thought that the Turbo switch would also reduce the FSB, but I guess I was wrong.

@NaoPb 10 месяцев назад

I commented on a previous video of using a post code card with an external display. Funny to see you already have one. About the cpu: everyone makes mistakes! I am glad that at least nothing was damaged. Oh and about the thermal paste. The bit at the end will inevitably dry a little and then become stuck. When using the syringe type, I try to pull the syringe first until it becomes loose. Then I press down to apply. This saves you from accidentally applying too much paste.

@scrap_computing 10 месяцев назад

Yeah these external displays are pretty useful! Thanks for the tip, I will try it out next time :)

@rs-qq3os 10 месяцев назад

For better desoldering and avoid using hot gun I'm wiggling the desoldering gun tip around the hole . It makes that chip pin is free and does't stick to the board. Anyway great job !!

@shaunclarke94 10 месяцев назад

I'm pretty sure he does this already.

@scrap_computing 10 месяцев назад

Yeah, I usually do that, but this only works well if the pins are centered.

@shaunclarke94 10 месяцев назад

Thats one tough CPU! Crackling sounds, burned up and burned the socket and it still didn't die.

@scrap_computing 10 месяцев назад

The DX33 CPU did die, but the interesting thing is that if you plug it in (the right way) it doesn't get hot or anything, it just doesn't work. I am thinking of removing the die cover to see if there is any visible damage.

@ayan.debnath 10 месяцев назад

I always put a RED and WHITE point on the CPU Socket. No way to miss. Few months ago, I bought a AM4 Motherboard. It had also bad markings, impossible to read/see. I put a big WHITE DOT....

@AladimBR 10 месяцев назад

We do silly things when tired. Some months ago I plugged the power connector inverted o a Toshiba DVD Rom IDE drive. Yes, even molex connectors can trick you. It burned an IC on the DVD drive board. I put it aside, maybe I can replace the IC… drives are still cheap, so I’m not doing that in the short term. As for checking all jumpers on a motherboard: it is a best practice and you will never forget it again 😅

@scrap_computing 10 месяцев назад

Yeah when you get tired you get confused and do all sorts of silly things. Wow it is hard to get the molex connector in the wrong way :)

@Inject0r 9 месяцев назад

Don’t be fooled by the turbo switch. I have come across that exact page multiple times, without it being the logical solution. I’ve put aside the motherboard a lot of times, because I couldn’t get it to perform as it should. I eventually found out that one of the VLB slots had D4 connected to ground, which causes the cache and performance issues. To make matters worse, another VLB slot also shorted the LKEN# to +5V, which occasionally caused the motherboard to either halt or not boot at all.

@laudennn 10 месяцев назад

try using some flux for your desoldering homie, will help not heat soak and prying against the board. that lead free solder doesn't like to melt. great video thanks. killing it!

@Vanessaira-Retro 10 месяцев назад

Great video! And of course it's the turbo switch. XD

@scrap_computing 10 месяцев назад

Yeah these sneaky turbo switches!

@SianaGearz 8 месяцев назад

I think the stubborn pins of the RTC might have come loose easily with desoldering needles, which are sort of hollow tubes that come in a kit of a bunch of sizes with handles.

@ruthlessadmin 10 месяцев назад

That looks like yet another variant of the infamous PCChips M912 (mainly known for some having fake cache). I have run across at least half a dozen different variations of extremely similar layouts, each touting different manufacturers and only slightly different design choices. For instance, some have a barrel battery, others coincell, while still others use a battery+clock package, like this one...Other differences may include jumper/vrm layout, and keyboard controller vs silkscreen vs blank solder pads above the outer most ISA/VLB slots. Frick, I need to create a spreadsheet or something as these boards are especially close to my heart because my first motherboard was one of these variants.

@scrap_computing 10 месяцев назад

There are tons of similar boards on theretroweb!

@ruthlessadmin 10 месяцев назад

@@scrap_computing Yeah, I'm aware of that but last I checked they only had one or two other variants listed on the M912 page. I suppose in that context, they're only interested in 1:1 identical boards, whereas I'm seeing many that aren't quite identical but really close.

@llamallarry 10 месяцев назад

An easy mistake to make. I fried a k6-2 the other day. The auto voltage feature of the board was not enabled and smoke came from the CPU 😊

@scrap_computing 10 месяцев назад

Haha yeah, there are so many things in such old systems that are not fool proof. Setting the voltage jumpers always makes me nervous, so I usually check the voltage on the socket before plugging in the CPU.

@Neksus-M06 10 месяцев назад

It once happened to me. A pin "exploded" but board and cpu were still working.

@nigelrhodes4330 6 месяцев назад

I actually have one of these boards I find it to be quite a decent unit although I also have an Asus VL/I-486SV2G4 so I find that one hard to beat.

@detalite 10 месяцев назад

What desoldering gun are you using. Is it any good? I have ZD-915 but it's barely enough for lead solder, and not suitable for lead-free solder.

@scrap_computing 10 месяцев назад

I also have the ZD-915. It's not great. Regular cleaning helps, and using hot air while desoldering also helps quite a bit. I wonder if a soldering iron with a built-in pump would work better.

@detalite 10 месяцев назад

@@scrap_computing Recently i found S-997P desolderin gun. It looks like a nozzle have a thread (like on DEN-ON SC7000Z) so the termal conductivity can be better. The problem is that i didn't found any reviews so I i can't fully confirm how it works.

@SianaGearz 8 месяцев назад

@@detalite That looks like the single pump version of the dual motor S-998p that has been reviewed. And Gaojie PW-993 appears to be a related item again? Anyway good luck.

@Megatog615 10 месяцев назад

you can just gently push the pins away from their soldered places with a soldering iron to loosen them. no need for hot air

@scrap_computing 10 месяцев назад

Yeah I usually do that, but it doesn't always work and you need to reapply solder and try again.

@Jack7277 10 месяцев назад

I hate these 386/486 cause there is no visible key like on pentium and go on. I mean you can insert the cpu in any way, hate this

@scrap_computing 10 месяцев назад

Yeah, they are not fool proof, and you can easily kill them if you are not careful.

@guayabito6946 9 месяцев назад

But how can you insert a CPU the wrong way, the socket itself should not let you insert it. Also Those CPUs have thermal protection. I remember I built a computer once where the heatsink fell off and the computer would start and shut itself off to prevent damage to the CPU.

@scrap_computing 8 месяцев назад

The 486 sockets, unlike any later sockets, will let you insert the CPU any way you want. So the PSU's 5V and GND were shorted through the CPU pins.

@guayabito6946 8 месяцев назад

@@scrap_computing ok