Reviving a 32-Year-Old Corroded Motherboard!

[@bitsundbolts]

For anyone having issues with the AI voice, I'm sorry, I must have overlooked a new feature available on KZbin. It won't happen in upcoming videos because i'll disable that feature. You can return to the original audio track in the video settings under 'audio track'. Sorry for this.

[@Manfred-123]

For other users that can't (good) understand English, it's a "usable" option, but the AI voices is a little bit crazy... I hope, YT will fix this problem (AI and default language track (English)) and other peoples can use the AI translation 😉

[@bitsundbolts]

Unfortunately, i have to disable that feature on my end due to too many complaints. I wouldn't be surprised to see an update for this feature soon. It should be opt-in.

[@pvc988]

@Manfred-123 Has KZbin ever fixed something or removed useless, annoying feature that everyone hates? I am suprised that it is even possible to turn it off. Unlike, for example, automatic title translation.

[@drPeidos]

@@pvc988 Agree, automatic title translation works terribly.

[@pvc988]

@@drPeidos Doesn't matter how good or bad it works. The problem is that it can't be disabled. It has to be CIRCUMVENTED by 3rd party browser addons. It's "You'll have no choice and you WILL be happy. Like it or not" kind of philosophy.

[@philscomputerlab]

These late era SX motherboards are really nice! Simple design and the performance is excellent for old games that are speed sensitive. 😊

[@bitsundbolts]

It is a nice board, but I do prefer my 386DX-40 with 128KB cache. I have another board that needs help - that one is equipped with a TI 486SLC/E chip (which probably has 1KB on-die cache).

[@philscomputerlab]

@bitsundbolts Nice 🙂

[@VladoT]

Phil, your old posts on Vogons are invaluabe these days helping us retro enthusiasts.

[@drewnewby]

At some distant point in the past, I decided I didn't need my boards older than socket 3, regrets...

[@mal2ksc]

This is why I say "the best 286 retro gaming box is a 386sx". The motherboards are practically identical, and if you don't use the 386-specific operations, the 386sx may as well just be a high-end 286. This is _why_ Intel made them, to claw back the market share it was losing to Harris and its 20 MHz 286 while impacting board integrators as little as possible, so practically every 386sx board is just an optimized 286 design. The 386sx is ever so slightly (like 1 or 2%) slower than the 286 when running purely 16-bit code, but this is more than offset by the ability to crank up the clock speed. You also gain from the hardware not being quite as old and you can mostly take that at face value since this is pre-Capacitor Plague either way. Newer is better _unless_ it puts you into the 1998-2003 region, then it might not be.

[@twiterMatt]

For me, watching when you are resoldering capacitors, connectors and other parts on this board are really relaxing! Good job :)

[@bitsundbolts]

Good to hear :) Thanks for watching and commenting!

[@DefenderOfBoston-yo2tl]

holy macaroni! there is truly no piece of retro hardware that is beyond repair for you, is there? absolutely amazing job! it is always sad to find such lovely hardware in such a bad state and it would seem too hopeless and depressing for me to even try fixing something that far gone, but you prove time and again that anything is possible with talent and a sheer endless amount of determination. i really had my doubts but started believing about halfway through. hats off to you! "firing it up" is exactly the right choice of words for a board with tantalum caps! 😄 i was at the edge of my seat, both with anticipation about the caps and about the repair! tantalums should always be completely eliminated proactively from any board imo. just not worth the risk. what makes me particularly happy about this restoration is, that this board is so very similar to my first pc, which i own to this day. same specs / same soldered amd 386sx-33 (minus the sxl iirc) and same bios. yours is a tad faster in system information though, mine only achieved a score of 23.2 last time i checked. wolfenstein 3d / spear of destiny / blake stone are of course the perfect games for this machine, this took me way back to some hot summers (partially) spent in my grandparents' basement with a good friend of mine! doom was indeed a pain, but it ran well enough on the minimum screen size. back then, we had to use our imagination for upscaling! 😂

[@bitsundbolts]

Haha, yes, good imagination was required when you play Doom on the minimum screen size 😅. I'm happy the board works! There might be an interesting video coming up with a CPU swap! You shouldn't miss that one either!

[@DefenderOfBoston-yo2tl]

​@@bitsundbolts sweet! i also want to play around with my board a bit once i have the time (i.e., in the distant future 🥲). like socketing the oscillator and finding out if/how far the cpu can be overclocked. i'll have to find (and fix) a mysterious source of instability first though that became apparent last time i played around with it.

[@bitsundbolts]

Uh, that's interesting! I hope you'll find the time and the source of the instability of your board!

[@DefenderOfBoston-yo2tl]

@@bitsundbolts thanks! it will definitely take me years to get around to it, but it's also a certainty that i will. 😉

[@GizmoTheGreen]

as you say perhaps from a practical perspective fixing the board is not worth it. however as content for us viewers I think it's priceless :)

[@mal2ksc]

It depends on two things really: how much time/effort/money/resources do you want to invest, and what's worth the effort. I wouldn't rehabilitate Turbo XT motherboards, for example, if there's _anything_ more interesting to look at instead. 386sx boards aren't that hard to come by, so I would agree with leaving this at the scrapyard and spending the time on multiple not-quite-as-broken projects.

[@bitsundbolts]

Well, I might have a nice project for this board. Overclocking and replacing the CPU with a TI 486SLC to get some cache! Even if it's just 1kb 😅

[@OzzFan1000]

What an amazing restoration! Good to see old technology brought back to life.

[@bitsundbolts]

Thanks!

[@mariokuntzag3206]

Einfach geniale Arbeit, danke das wir teilhaben dürfen. Bitte mehr!

[@toma.cnc1]

Watching you put all that effort and time into fixing these old boards (great job) makes me feel really bad for throwing hundreds of those in the trash back in the day. I still have some old stuff left, laptops (from 486 and up) and some Voodoo's and other cards, but no MB.

[@bitsundbolts]

It's normal to get rid of old hardware. That 386 was no longer desirable when the 486 DX2 came out. Then the Pentium changes everything again. Now, thirty years later, we remind ourselves what we threw out such a long time ago 😔

[@xDJxGNOMx]

Although repairs like this are absolutely painful to you (understably), it is however a great oppurtunity to learn for all of us viewers. Thank you so much for your videos.

[@rogiervanl]

As others already stated, very relaxing to watch you solder and desolder. Great job!

[@joehorecny7835]

Maybe you can get some replacement drills, yes they are very fragile. Great restoration!

[@bitsundbolts]

Thank you very much for your support! I'll definitely get a new set of those drills! Thanks again! 👍

[@AndrewFremantle]

Remarkable repair. I wouldn't have thought that would be repairable.

[@bitsundbolts]

Half-way through I regretted my decision to take this board home.

[@drewnewby]

So many times, the more bodge wires and broken IC legs, the more regrets.

[@simontay4851]

It was in the scrap yard for a reason. I would have had one look at that board and said " No, fk that - no chance. Its too far gone.

[@bitsundbolts]

That is what I thought! I walked away!! Then, 10 steps away, I turned around 😅

[@samuraidriver4x4]

Great job on the fix👍 You really have alot of patience that's for sure. When there is chips under socketed chips there is the option of putting a socket in a socket to raise them up a bit. You do need the extra sockets, something to keep in mind when you have spare sockets on hand. I always replace all tantalum capacitors in older stuff. Even tantalum's on the 3v3 rail seem to explode every once in a while.

[@bitsundbolts]

Great idea with socket stacking. I'll keep it in mind for the future - I am sure it will come in handy! I didn't have a 3v3 tantalum explode on me yet, but that is probably due to lack of experience with those hotheads!

[@caleblancaster5471]

That board was a mess. Great work!

[@drewnewby]

The ol' socket sandwich.

[@RommudohDev]

it would be nice, if there were sockets with longer legs - but I don't know if there is a market for them

[@Godzilla941]

I also have one of these boards! I pulled it out of storage and got it working this past summer, the battery had just started to corrode the solder joint around one of the legs...I got to it just in time. I couldn't find too much information on it, either, but the other crystal socket is for the 387, and the jumper next to the 387 socket selects either the CPU clock or that crystal socket for asynchronous operation. I have the book for this board buried SOMEWHERE in this house, and if I ever find it I'll be sure to post it over at T.R.W. I would have posted a picture already, but I was going to do that after I found the manual and swapped the 387 socket back to the original brown one (troubleshooting bad 387s...) Chipset appears to be a relabeled Acer Labs M1217 judging from the BIOS string in case that helps anyone. With a (fast) FPU of questionable pedigree (relabeled in China), it will do a whopping 1.1FPS in Quake bench included with Phil's test suite... 🤪

[@bitsundbolts]

Haha, nice benchmark score in Quake! Thanks for the info regarding the empty crystal socket! Good to know. I hope you'll find that manual 😄

[@peterilling1627]

Good to see old tech being saved well done Good to see all that hard work you put into it a working main board.

[@bitsundbolts]

Thank you! Yes, I am happy that it ended with a working board!

[@Neksus-M06]

Been there, I know how you felt. It's crazy when every single solder point or joint or trace and holes have to be repaired. At least you didn't have to desolder the chipset :)

[@bitsundbolts]

If the ISA slots would have been affected, I probably would have left the board there. Now I am happy that it works, but it was a disproportionate amount of work!

[@mikes989]

@@bitsundbolts An excellent wire for repairing traces is the one from the 3 1/4 floppy motor. It is thin, malleable and strong, it holds the shape very well, and once the lacquer coating is removed, the tin sticks to it perfectly.

[@anmishel]

ммммм пустой слот для математического сопроцессора :) помню помню, был у меня такой когда то давно :) В этом плане предпочтительно DX версия 386, там уже и VESA шина была ! Ах сколько эмоций она доставила когда наконец то я приобрел видеокарту tseng et4000 и звуковую карту sb gold ! Эх были времена ! ms dos 6.22 norton commander и игры которые влезали на 5 дюймовую дискету :)))))))) Спасибо автору за видео, отправил меня в воспоминания детства

[@dragoncracker]

I was amazed that with this much corrosion you still managed too rescue this board, fantastic job!

[@bitsundbolts]

Thank you!

[@tony359]

I'm not sure I would have attempted to recover that board, well done! Very thorough job and it worked at the end!!

[@bitsundbolts]

It was a big gamble to take this board home. Luckily, it POSTED after all that work!

[@tomasz89g]

You've done well, showed a lot of persistence. I didn't think it would work, that corrosion looked very bad. It is an interesting board and restoration if only because it wasn't yet on the RetroWeb.

[@bitsundbolts]

Unfortunately, the board was already there, but without a picture and without the BIOS image. I somehow didn't find the board based on my search criteria. It must have been because I selected the BIOTEQ chipset in the search, but on TRW, it's listed with an ALI chipset. So, that BIOTEQ seems to be indeed a relabeled ALI chipset.

[@xenoxaos1]

9:51 I would have slid the plastic off and done the pins individually

[@naturelmania]

I would like to point out that in my experience the best way to desolder a pin is to use solder pump. There are plastic and aluminium ones out there. You just melt the solder and press the pump which sucks out the melted solder. You can clear a pin really fast which also evades the possibility of damaging the pin using long exposure to heat. You can see that I'm using in my video 😉 really recommend it.👍🏼 Also loves the background smooth jazz. Awesome video to watch. Thanks a lot. 😊

[@bitsundbolts]

I think I am too clumsy with a solder pump - or I just need to practice more. I never managed to clean multiple pins easily. The desoldering gun works better for me. But it all depends on personal preference!

[@Paul-xs7ks]

These are becoming rarer, yes a lot of work but if it what you enjoy then it is totally worth it. And look what you achieved, another great motherboard saved. And the buzz when you realize you won the fight. If I found one in that state I would absolutely grab it. If it is not repairable then it might help save another board. Great job.

[@bitsundbolts]

I totally agree! Since the board worked after the restoration, I am happy I took the board home. I don't have many 386 boards - and there will be at least one more video about this board. Thanks for watching and commenting.

[@harvaldi]

I admire your perseverance. Honestly I thought that this board would be your defeat. Once more You're victorious! Great job!

[@bitsundbolts]

Hehe. Well, it wasn't easy! Thanks!

[@Dysturbed-00]

I tried doing this so many times when I was 10-14 yo back in the 90's I didn't have proper equipment and wasn't very successful. Really brings back good memories on the old crafts table in the basement working on boards. This was way before I took electronics assembly classes and circuit basics.

[@bluethunder8383]

Enjoyed the restoration, never doubted you but it was a lot more involved then I expected

[@bitsundbolts]

Hehe, thanks! Yes, it was a lot of work! But I'm happy it works now!

[@ajdothack]

Thank you for that hard work learned a lot from your repair videos keep it up!

[@bitsundbolts]

Thanks for watching and commenting!

[@auxie22]

Incredible restore BuB... The amount of hard work and effort you put in and then seeing it boot up was amazing! You probably have had 386 boards which were much easier to repair but considering the outcome it wsas definitely worth it! Incredible work!

[@bitsundbolts]

Thank you! Well, I got some nice ideas from my audience on what to do next with that motherboard.

[@MarcoGPUtuber]

46:38 if you want to socket those logic chips, the height wouldn't be an issue if you double socketed the keyboard chip. Just make the keyboard chip higher with two sockets.

[@djdoo]

Wow I didn;t know Biostar has been such an old MB manufacturer, my everyday B550 Ryzen MB is a Biostar! I honestly thought that Varta this time would have beaten you but I was really happy to prove wrong ! Excellent work and video, Keep up, cheers from Greece! Jim

[@bitsundbolts]

Thanks! Yeah, this one was a tough one and it takes a lot of time. Well, maybe if someone discovers their old childhood system in the attic and it suffered from battery damage - it might be possible to save it with enough motivation 😀

[@dustinhipskind7665]

If you wanted the hidden chips to be in sockets, you could. You could use a raised 90° angle DIP socket, or a long leg socket, to have clearance for the keyboard IC.

[@michaelturner2806]

I'm just barely 20 minutes in and I'm surprised you didn't just give up after seeing the extent of the damage. At some point I'm sure this just becomes exercise and experience rather than a real attempt at saving this board. If anything works in the end you're a certified miracle worker.

[@bitsundbolts]

Wasn't that around the time I said "we'll get this board working again"? 😅 It definitely was a tough board, but as you said, it's exercise! I learned that I should use that desoldering gun! It will save a lot of time and wick. I also saved the 40 pin socket. I learned about socket stacking from my audience, and so much more! It was definitely worth it!

[@ivankuznetsov5618]

Очень интересно было смотреть, вы профессионал!

[@bitsundbolts]

Thanks!

[@DeadCatX2]

2:05 those vias are around mounting holes and are intended to improve structural performance; they resist the compressive force that occurs when screws are used to hold the motherboard in place, reducing the risk that the PCB layers get crushed. You can actually see faintly how the inner copper layers have voids around the mounting holes, meaning I would expect they're electrically isolated, or possibly connected to ground on a layer we can't see from the bottom

[@bitsundbolts]

Ah, interesting. I always wondered why there are perfectly spaced holes around those screw holes. Thanks for sharing! Good to know if I ever design a PCB that needs to be screwed somewhere.

[@emprsnm9903]

On motherboards; A good portion of the time resistors are logic pull-ups. When in backplane-doubt, imagine that one is and see what value it has; 1K,10K,20K are likely pull-ups. With the exception of the analog circuits in the [cpu voltage regulator section], audio chips, and [VGA rgb signal] lines. Excellent work on this little board! I think I had one of these when I was a teen? Though it was 40mhz. I found out the hard way of not mixing a pair of 1MB, and a pair of 4MB simms in those four slots, as it was combined as a single bank! Windows 3.1 didn't like it half the time, randomly🤭 Now it's been 30 years, but I remember that turning-on the 'internal cache' helped my performance a bit? Even if it was only 4K/8K inside the northbridge chip

[@MarcoGPUtuber]

21:36 I think it is worth it. I really like this content and it helps me learn. If it is REALLY too far gone, it becomes a good parts board. Other things like CPU Sockets can still break or chipsets and they're not being made anymore. I pick up everything.

[@bitsundbolts]

Haha, I guess that is what I'll be doing until I run out of space at home 😅

[@MarcoGPUtuber]

@@bitsundbolts You can always sell repaired boards and put any proceeds back into the channel. Could even engrave your logo onto an available ground plane. That's what I'm thinking of doing to my own repaired boards. Could help the channel and keep part prices from going out of control. What good are they if they just get shredded? Nothing lasts forever, but we can slow it down.

[@mikes989]

An excellent wire for repairing traces is the one from the 3 1/4 floppy motor. It is thin, malleable and strong, it holds the shape very well, and once the lacquer coating is removed, the tin sticks to it perfectly. I just have some windings from some destroyed units, for that, breadboarding and prototyping

[@bitsundbolts]

Haha, the poor floppy drives 😅. I have a few floppy drives, but I have a feeling they all work.

[@mikes989]

@@bitsundbolts the wire from some similar small motors may be like that too

[@foxmoulder2430]

Enthusiastisch Repariert. Sehr gut gemacht. Ich hätte da nicht so viel Ehrgeiz investiert, eher in alte Röhrengeräte aus den 50-80er jahre

[@esc2dos]

Thankfully we have a community of like minded people here, anyone else would have looked at that and said "JUNK". Love your perseverance, you truly appreciate these old boards otherwise why would anyone put themselves through that. Did kinda wonder if those Vias would give you grief. Congrats on your excellent work.

[@bitsundbolts]

Thanks! Yes, corroded vias definitely are the ones I am most concerned about.

[@tobias_off]

Another job well done. Good to see this poor board alive again. You can improve the revealing of the traces on the inner layers if you play around a little with the intensity of your light used to shine through the board. The glass fiber of the board material reflects and guides the light very well and that makes it difficult to see the inner trace sometimes. Also if you cannot see the trace shining from one side of the board, turn it around and try it from the other side. This helped me in the past repairing an eight layer board (i have still nightmares 🙄).

[@bitsundbolts]

Thanks for the tips! I'll try that next time. It was odd to see no trace leaving from that via.

[@imperia777]

What an effort. Amazing work.

[@bitsundbolts]

Thanks!

[@GGigabiteM]

These boards are always worth attempting to repair. While they may still be somewhat available, more and more of them are rotting away every day from battery bombs, and they'll eventually become rare and hard to find. Save more of them now to have more available later. These types of boards are also good learning tools for someone getting into board level repair. The board is already dead, you can't do much worse to it, so if the repair is a failure, it's not a big loss. These boards can also be a source of spare parts. One interesting thing to do with this board would be to try swapping the Am386SX with a TI486SLC2. Since the BIOS seems to already support cache, it should support the 8 KB of L1 cache in a SLC2, which would give you a much wider range of performance options. A TI486SLC2 clock doubled at 66 MHz with the cache enabled is about on par with a 486SX 33.

[@bitsundbolts]

I think this is going to be an interesting project! I got this recommendation a few times now with the 486SLC. I'll keep an eye out on one of those CPUs. Clock doubled would be nice too!

[@GGigabiteM]

@@bitsundbolts They're getting a bit hard to find, so it would be a good idea to get one sooner than later. When I was looking for one a few months ago, it looks like stock of them dried up really quick, like someone bought a large chunk of the remaining stock of them for some reason or another. I was luckily able to find a lesser known part of the same speed grade that was 5v tolerant. The 3.3v parts seem to be more available because less things can use them without using level shifters and voltage regulators. I've seen some rather comical modifications on Vogons to boards that are 5v only to get 3.3v parts to work by lifting the Vcc pins and routing them to a LDO 3.3v regulator. They're reported to work by the people that did the mods, but that's a whole lot of extra work. The non-clock doubled parts have better availability, but they have less cache at 1 KB. I'm still able to source 25 and 33 MHz TI486SLC parts from UTSource for a reasonable cost, and I think they overclock well. My 50 MHz part overclocks to 66 MHz with a heatsink and small fan with no issues.

[@bitsundbolts]

I have a board with a 486SLC that should be compatible. Yeah, it has the lower cache size and it isn't clock doubled, but it should still work for the project to swap the CPU. Maybe one day I will get lucky and find one of those CPUs at the scrapyard.

[@PROSTO4Tabal]

This older motherboards are just like babies in mother arms

[@ewan8618]

Wow you are a circuit dentist!

[@bitsundbolts]

Haha, thanks 😅

[@snap_oversteer]

That's some serious repair work, great job!

[@ronnyroy-fd1li]

30:25 if you want to reliably see where vias connext to inner layers you need to do the light method from both sides. The PCB material scatters light quite heavily so you won't really see connections below the first inner layer.

[@bitsundbolts]

Good to know. I'll try that next time I have an issue like that.

[@Constantin314]

nice, Alex! brilliant exercise regarding patience!

[@bitsundbolts]

Thanks!

[@ApostolCV]

WOW! Great job! But hard and dirty !

[@bitsundbolts]

Thanks!

[@formatter]

Incredible job!

[@markg3506]

Very nice job!

[@Ale.K7]

Amazing repair!

[@r4z4m4t4z]

alright, nice efforts again! 386 sx 33 was my first pc build but it didnt look like that board. lol the apple tax

[@bitsundbolts]

Yeah, the Apple tax is pretty bad :( I started with an AMD 486 DX4-100. Still, I find 386 systems fascinating.

[@r4z4m4t4z]

@@bitsundbolts and now im off to pick up some socket 3 board with an overdrive 66 and a leaky barrel battery and also a diamond stealth 64 s3 vision vlb!

[@bitsundbolts]

Nice!!!

[@VladoT]

Few extra information: unlike 386SX, a 386DX will not boot with only 2 memory sticks because it expects 32bit memory which requires 4 x 30pin modules. Also, the Norton System Information benchmark for the "386DX-33" is based on a system with 32KB motherboard cache, so 386SX actually is not whole 10 points slower at executing instructions you just need cache.

[@bitsundbolts]

Thanks for clearing that performance difference in System Information up! That makes a lot of sense now. Thanks!

[@Shoikan71]

Awesome work dude.

[@bitsundbolts]

Thanks!

[@deplinenoise]

Wow this was rough. Good work!

[@bitsundbolts]

Thanks!

[@peterkornaukhov9990]

Handling with dirty crap online and everything for repair here... very good video, thank you

[@alexloktionoff6833]

Nice to see that 386SX board can support 4x4Mb SIMs. Probably this is because of two 245 buffer ICs near SIM sockets?

[@bitsundbolts]

I'm not sure if it is because of the two 245 chips, but a 386 SX should be able to address 16MB. Not sure if it depends on those other ICs.

[@alexloktionoff6833]

@@bitsundbolts I suspect that 386SX chipsets do not have enough pins to address 16MB and require external buffers to multiplex/reuse shared pins.

[@drPeidos]

The struggle to not break thin drills is real, I've broke so many :S Hope you get more terrible boards, this was great. Even if in the end the board did not work, I think it made an excellent video. If you feel these board take a lot of time, maybe try working on them on short bursts during several days/weeks, so you don't get sick of them.

[@bitsundbolts]

Oh, the board worked at the end 😁. I used it for the two videos coming next week! You have a point. I think I should take longer breaks when a project takes several days.

[@gbclab]

Very well done

[@666KoXz666]

noo not leave at scarpyard, I love watching that. ASMR

[@lexluthermiester]

@BitUndBolts As usual, you've done some damn good work!

[@bitsundbolts]

Thank you!

[@mal2ksc]

You _could_ socket those 74-series logic chips, but you'd have to double-stack the larger socket around it to make the clearance.

[@krizator]

Excellent jobs! 😃

[@bitsundbolts]

Thanks! 😄

[@matthewday7565]

The cache option suggests that it would be ready to run a 486SLC

[@bitsundbolts]

Hmmm. I have a board with such a chip. I wonder if I should try to transplant the chip over to this board. Coincidentally, it is the board I took the power connector from. Thanks for pointing that out!

[@MrQuist125]

Tuff board. Nice work sir :)

[@SeanBZA]

Think I have one in the garage, in an old 386SX 33 motherboard that I used for a good few years after it had been declared obsolete, as it would not run Win95. Used it to run some bespoke equipment to replace the original controller it had, which used a lot of 555 timers and 4700 uF capacitors to do timing, and thus was rather temperamental as they aged and got leaky.

[@dolphhandcreme]

These carbide drillbits work best with high rpms and a small drillstand. They easily fit in regular dremels. The dremel drillstand itself is a bit to wobbly for the smaller diameters and needs excessive tuning to work.

[@bitsundbolts]

I need to figure something out. It's not the first time I break those drill bits. I wish they'd fit in my engraving pen.

[@dolphhandcreme]

@bitsundbolts try to get something with 3mm front. At university, we built a small drill stand for drilling pcbs just with a motor, a short metal pipe with 3mm diameter and some plates for the vertical movement.

[@djdjukic]

I would say it was worth repairing this rare motherboard! Didn't know Biostar even made chipsets...

[@LynxCarpathica]

BIOTEQ... More like BIQHAZARD lol Lovely :D

[@bitsundbolts]

Haha, true... This one was bad and had all sorts of stuff growing - gunk and crystals!

[@justinkovacik9436]

Wow that was incredible I thought for sure this board would not POST at all

[@bitsundbolts]

This was a tossup. Luckily, it worked after all that effort!

[@hector1067]

excelente amigo tu canal en español muy bien saludo de venezuela

[@bitsundbolts]

Thank you!

[@cosmefulanito5933]

40:40 You don't have to use flux for everything you solder. Truhole components don't need it. The tin you use for soldering already has flux.

[@drewnewby]

With this amount of oxidation and corrosion, you really do. Desoldering alloy is often needed in addition to fresh solder. The rosin core is not enough for a board out in the desert so long.

[@bitsundbolts]

My solder is from 1998. It is still ok, but the flux inside isn't as good anymore. And as @drewnewby said, flux helps with the condition of the board. Even though I removed most of the corrosion, some pads still have issues with heat transfer and solder attachment.

[@harryhirsch723]

@38:20 What kind of copper traces are these? Anyone knows ?

[@ToTheGAMES]

Might be copper tape, not sure.

[@bitsundbolts]

Yes, it is copper tape.

[@SireSquish]

26:40 It would have been some nice zen to see you cleaning those out, maybe even in high-speed montage :)

[@Pedrao_Mr.P]

opaaa show, audio em português, muito boommm!!!! 😀

[@mrgatogrande4284]

Wait! How do you change the color pallette of those bioses? I hate the one that shows by default.

[@bitsundbolts]

With the function keys F2/F3 - you circle through the predefined color palettes.

[@krizator]

Hotkeys for switching are written at the bottom of the page

[@mrgatogrande4284]

​@@bitsundboltsThank you!

[@Manfred-123]

😮 respect 🙂😇😎 I've got the GMB-486UN and I want use a external battery, the ton battery is not on the board, but I don't know which is the right position for pin 1 to connect battery, I want to use DuPont connector with 2032...

[@bitsundbolts]

I assume you have a pin header with 4 connections for the external battery. Use a multimeter continuity mode (beeping) to find the negative/ground pin. The black probe goes on a screw hole (or one of the center pins of the power connector) and with the red probe you can test the outer pins of the battery connector. One of those pins should make your multimeter beep - that's the ground or negative terminal for your external battery. Make sure your battery is properly wired as well - so that the negative terminal connects to the pin that made your multimeter beep.

[@MonochromeWench]

The socket for the extra xtal will be so the FPU can run with an independent clock to the cpu. FPU usually ran at half cpu clock but don't need to if you get a very fast one and you have an extra xtal. FPU on a late model 386SX is a bit silly though, if you needed an FPU in the early 90s a 486 DX would be a better choice all round. A bit pricey of couse if you just needed an FPU but if you needed an FPU you were probably using pricey software like Autocad and could really use the extra grunt of a fully 32 bit 486.

[@bitsundbolts]

Thanks for that info about the FPU and the empty socket. I don't have a PLCC FPU and as you said, it is probably not worth it looking for one. The use case will be very limited on a 386SX.

[@Nelson68k]

82C3860 points to a VLSI chipset. They have a similar name. Probably just Biotaq branded.

[@bitsundbolts]

I got an answer from the good folks over at The Retro Web. Apparently, it is a rebranded ALi M1217 (you can see this model number in the POST string).

[@SireSquish]

Future video idea - The Tantalum Torture Tester. Bascially a small circuit you can feed in 12V and see if the tantalums have a tantrum or not when exposed to 12V. Of course, with you far enough away to enjoy the sparks as much as we do.

[@bitsundbolts]

Haha - you are reading my mind!!! I kept those tantalums precisely for that purpose! I will continue to collect a few more and then have a tantalum party with fireworks :)

[@SireSquish]

@@bitsundbolts It'll need a good name. Something better than "The Tantrulum".

[@DxDeksor]

not sure if the AT psu connector are still made or cheap to get, but I think that the pins used in them are standard. Can't tell what they are, but it could be worth looking. The plastic itself is fine, so why not just replace the pins and keep the plastic ? :)

[@bitsundbolts]

Good point. I haven't seen replacement connectors or replaced pins. I think I'll just get a few of those connectors from the scrapyard. The problem is that there are always boards attached to those connectors! 😅

[@mmllmmll22]

Have You tried using ultrasonic cleaner for things like that keyboard connector? Also it may help getting rid of residue after battery leakage. And clean board to pristine state.

[@bitsundbolts]

I have an ultrasonic cleaner coming my way! I'll definitely try it on boards and connectors that are corroded. This will probably come up very soon in my channel.

[@adrian_sp6def]

46:43 can You use socket in a socket sandwitch for those places when You rise a chip inside by uisng socket?

[@bitsundbolts]

That would be possible for raising the chip, but there isn't enough space inside to place the smaller sockets for the logic ICs - at least the sockets I have are a bit too wide.

[@Pulverrostmannen]

Having it fresh in mind that I just revived a Varta death 286 Toshiba Lapline myself that had suffered catastrophic damage in even more extent than this I absolutely know what this type of damage means. and more than 15 traces on my board was gone, like actually gone. dozens and dozens of of damaged parts of everything from connectors to vias to components. a real nightmare. but I got mine running again too. albeit way too much work for any sane person to waste on a such old computer board

[@bitsundbolts]

Congratulations on your 286 save! Yes, the amount of work that goes into those boards is insane! The reward? Hopefully a working board and a lot of experience and practice! That is the only way you can justify spending that much time on a board that's worth maybe 100 USD on a good day.

[@susanin177]

Excellent job! Thank you for your restoration videos. Can you tell, what type of wire you use to repair a broken trace at 37:12? It looks like one side of it is sticky and you just glue it at the top of existing one?

[@bitsundbolts]

Yes, it is sticky on one side. It's just simple copper tape. I had to cut it to the correct width. I then tape it just above the old trace, apply solder and solder mask. It should be ok. That's the first time I did that. I could have used a small copper wire, but they don't look as nice when covered under solder mask.

[@digidoidit]

I want to recommend you a solution that I use. A drill made of hardened steel, as you noticed, very fragile. Dentists have a Twisted File. They are flexible and quite strong.

[@bitsundbolts]

Interesting. I used the drills a few times now already and I get better in not breaking them. They usually break because I am rushing.

[@digidoidit]

​@@bitsundbolts give it a try and you may like

[@nalimko33]

great job!

[@bitsundbolts]

Thanks!

[@laurdy]

if the PCB is multilayered the VIA could be buried closer to the other side. So, try turning it over shining the light through the top instead of the bottom

[@bitsundbolts]

Could be! Maybe the PCB diffuses the light and makes the trace invisible. There has to be something leaving that via in the inner layers! I'll try it the other way around.

[@danielktdoranie]

I can’t believe you got this board to boot

[@bitsundbolts]

I was surprised as well. If that one tantalum capacitor wouldn't fail, it would have been a first try success, but that wouldn't be fun!

[@albertstorch5224]

Ich staune wie du mit Entlötlitze die Löcher frei bekommst. Kannst du mir den Trick verraten? Vielleicht ist mein Flussmittel oder die Entlötlitze nicht so gut? Sehr interessant dein Video!

[@SianaGearz]

Perhaps you just need to get lucky with the product quality. I bought several from Conrad which didn't work worth shit, and no tricks helped at all. But once i ordered a boatload of the cheapest cp-1515 on Ali, and that works just fine! Alternatively you could consider buying a quality brand product that is specialised on desoldering wick. Do not use wick which is too wide, its performance is going to be bad in principle. Don't use it straight off the spool - clip off a piece and tweeze it in. Do load it up with good quality flux. Consider pumping up the iron temperature, depending on iron construction it may well be necessary, and use a wide tip, like a knife, hoof or chisel tip.

[@bitsundbolts]

Der Kommentar von @SianaGearz hat so ziemlich alles was hilft das Ergebnis mit Entlötlitze besser zu machen. Ich benutze ein billiges Flussmittel von AliExpress welches als AmTech verkauft wird. Das hat immer gut funktioniert. Die Qualität der Entlötlitze spielt auch eine große Rolle! I habe ein paar andere ausprobiert die nichts getaugt haben. Und es hilft ~1-1.5 cm abzuschneiden. Dadurch wird die Entlötlitze heißer und das Zinn läuft eher auf das Kupfer. Ich habe auch viel ausprobieren müssen bevor es jetzt fast immer klappt.

[@bitsundbolts]

Exactly that! 💯

[@SianaGearz]

@@bitsundbolts I find for wick, and actually for many uses, the solid cake rosin from Poland in those green little tins works really well. It looks like amber glass, very transparent, slightly golden, really nice quality, just fascinatingly beautiful. You just take a little dropper bottle, crack the cake, pour in about 1/5th of a bottle worth with the chunks, and fill up the rest with isopropyl alcohol and then just wait a few days until it's dissolved. But yeah the white 559 or 218 paste flux from China is usually OK. Can't quite rely on it always being good, but you test it, if it's good, it's good.

[@albertstorch5224]

Vielen Dank für eure Tips und ich freue mich auf weitere Videos! 👍

[@JoCrt]

This is a mission. Board is a wreck

[@Santia558]

What kind of copper wire did you use to repair traces? It looked “flat” or almost like a “copper tape”. 37:15

[@bitsundbolts]

Yes, it's copper tape. It's sticky on one side and has a decent thickness. I used that tape in another video where I added the temperature probe inside an AMD K6-2+. It's an older video, but I think I am showing the tape in that video. Edit: the video's title is "The Ultimate AMD K6-2+ - with 3 MODS"

[@toddabbott781]

Back when I was 17 I got a used 386 SX-25 system. My brother borrowed it and fried the system so I got a used 486 DX-33 I think I went from 1MBB of memory to 4MB. I also had a 20MB hard drive and a 20mb hard card. I had a 5.25" floppy and a 3.5" floppy. I eventually bought a new system with a Cyrix PR-200. It was horrible and I refused to ever buy a pre-built system ever again. My next system I took that Cyrix and replaced the board,, CPU, and memory with a K6-2 350.

[@kb_3224]

Well done. My first computer was a 386sx 33 and I was wondering then if it was possible to overclock it by changing the crystal to 40 mhz. Can you check it now?

[@bitsundbolts]

That would definitely be an option! I'll put that on my list for future projects. I also haven't overclocked a 386 by replacing the crystal.

[@szymon3075]

Am386SX 2MB RAM... my 1st PC

[@MarcoGPUtuber]

23:41 That was me.

[@bitsundbolts]

Well, there you go :) thanks 👍

[@kj197734]

Did you and Adrian's Digital Basement get motherboards out of the same pile recently? Keep these repair videos coming.

[@bitsundbolts]

Haha, he fixed a 286 board a few days ago - I was very surprised to see his video a few days ago. I'm sure it's just a coincidence 😂

[@simontay4851]

For corroded power connectors, couldn't you file the pins back to good metal with a fine file and then tin them?

[@bitsundbolts]

That could be an option. Never tried that though. Those power connector pins are a lot harder to remove than the pins of the sockets.

[@ninedogs2418]

actually you can use small socket inside another socket. Just use second big socket like IC->socket->socket.

[@bitsundbolts]

Ahh, right. The could have been an option. But I would have to work something out since I don't have 40-pin sockets. And I checked, I also didn't have narrow enough sockets for inner sockets. Sanding them on the sides would also not work as they probably would crack. Luckily, the board works and there's no need to remove those chips anymore.

[@xenoxaos1]

Years ago I requested samples from ti for a rtc with nvram... Need to find a repair person that could use them